From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 22023 invoked by alias); 14 May 2012 15:37:03 -0000 Received: (qmail 20387 invoked by uid 22791); 14 May 2012 15:36:44 -0000 X-SWARE-Spam-Status: No, hits=0.2 required=5.0 tests=AWL,BAYES_50,FROM_12LTRDOM,KAM_STOCKGEN,KHOP_RCVD_UNTRUST,RCVD_IN_HOSTKARMA_W,RCVD_IN_HOSTKARMA_WL,SARE_BAYES_5x8,SARE_BAYES_6x8,SARE_BAYES_7x8,TW_BJ,TW_EG,TW_TM,TW_XB X-Spam-Check-By: sourceware.org Received: from relay1.mentorg.com (HELO relay1.mentorg.com) (192.94.38.131) by sourceware.org (qpsmtpd/0.43rc1) with ESMTP; Mon, 14 May 2012 15:36:21 +0000 Received: from svr-orw-fem-01.mgc.mentorg.com ([147.34.98.93]) by relay1.mentorg.com with esmtp id 1STxJp-0006NU-MQ from Maciej_Rozycki@mentor.com ; Mon, 14 May 2012 08:36:17 -0700 Received: from SVR-IES-FEM-02.mgc.mentorg.com ([137.202.0.106]) by svr-orw-fem-01.mgc.mentorg.com over TLS secured channel with Microsoft SMTPSVC(6.0.3790.4675); Mon, 14 May 2012 08:36:17 -0700 Received: from [172.30.0.49] (137.202.0.76) by SVR-IES-FEM-02.mgc.mentorg.com (137.202.0.106) with Microsoft SMTP Server id 14.1.289.1; Mon, 14 May 2012 16:36:13 +0100 Date: Mon, 14 May 2012 15:37:00 -0000 From: "Maciej W. Rozycki" To: CC: Rich Fuhler , Richard Sandiford , , Subject: [RFD+PATCH] ISA bit treatment on the MIPS platform Message-ID: User-Agent: Alpine 1.10 (DEB 962 2008-03-14) MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Mailing-List: contact gdb-patches-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: gdb-patches-owner@sourceware.org X-SW-Source: 2012-05/txt/msg00515.txt.bz2 Hello everybody, I am cc-ing GCC and binutils mailing lists because while my proposal is contained in GDB, it is GCC and binutils that produce DWARF-2 records that GDB has to deal with. Feedback from all the parties involved is very warmly welcome, be it enthusiastic or more critical. I will therefore start with a short explanation of the matters considered, so that those of us with good ideas and extensive knowledge of our tools, binary formats, respective standards, etc. but who do not specialise in the area of MIPS processors have a better understanding what the underlying implication are. 0. Introduction As some of you may have been aware, GDB has had issues with handling MIPS16 binaries related to the use of the ISA (Instruction Set Architecture) bit as the selector between the regular MIPS and the MIPS16 execution (ISA) mode. With the imminent addition of microMIPS support to GDB these issues will apply there as well as the microMIPS execution mode uses the ISA bit exactly as the MIPS16 mode does. 1. Background information The MIPS architecture, as originally designed and implemented in mid-1980s has a uniform instruction word size that is 4 bytes, naturally aligned. As such all MIPS instructions are located at addresses that have their bits #1 and #0 set to zeroes, and any attempt to execute an instruction from an address that has any of the two bits set to one causes an address error exception. This may for example happen when a jump-register instruction is executed whose register value used as the jump target has any of these bits set. Then in mid 1990s LSI sought a way to improve code density for their TinyRISC family of MIPS cores and invented an alternatively encoded instruction set in a joint effort with MIPS Technologies (then a subsidiary of SGI). The new instruction set has been named the MIPS16 ASE (Application-Specific Extension) and uses a variable instruction word size, which is 2 bytes (as the name of the ASE suggests) for most, but there are a couple of exceptions that take 4 bytes, and then most of the 2-byte instructions can be treated with a 2-byte extension prefix to expand the range of the immediate operands used. As a result instructions are no longer 4-byte aligned, instead they are aligned to a multiple of 2. That left the bit #0 still unused for code references, be it for the standard MIPS (i.e. as originally invented) or for the MIPS16 instruction set, and based on that observation a clever trick was invented that on one hand allowed the processor to be seamlessly switched between the two instruction sets at any time at the run time while on the other avoided the introduction of any special control register to do that. So it is the bit #0 of the instruction address that was chosen as the selector and named the ISA bit. Any instruction executed at an even address is interpreted as a standard MIPS instruction (the address still has to have its bit #1 clear), any instruction executed at an odd address is interpreted as a MIPS16 instruction. To switch between modes ordinary jump instructions are used, such as used for function calls and returns, specifically the bit #0 of the source register used in jump-register instructions selects the execution (ISA) mode for the following piece of code to be interpreted in. Additionally new jump-immediate instructions were added that flipped the ISA bit to select the opposite mode upon execution. They were considered necessary to avoid the need to make register jumps in all cases as the original jump-immediate instructions provided no way to change the bit #0 at all. This was all important for cases where standard MIPS and MIPS16 code had to be mixed, either for compatibility with the existing binary code base or to access resources not reachable from MIPS16 code (the MIPS16 instruction set only provides access to general-purpose registers, and not for example floating-point unit registers or privileged coprocessor 0 registers) -- pieces of code in the opposite mode can be executed as ordinary subroutine calls. A similar approach has been more recently adopted for the MIPS16 replacement instruction set defined as the so called microMIPS ASE. This is another instruction set encoding introduced to the MIPS architecture. Just like the MIPS16 ASE, the microMIPS instruction set uses a variable-length encoding, where each instruction takes a multiple of 2 bytes. The ISA bit has been reused and for microMIPS-capable processors selects between the standard MIPS and the microMIPS mode instead. All our tools have supported, to the various level of quality, the MIPS16 ASE instruction set and associated binary file structures for a long time now. Support for the microMIPS instruction set and binary file peculiarities has been recently added to binutils and is being reviewed for GDB; my understanding is the corresponding GCC bits are supposed to follow in a not so distant future. Anything considered here therefore equally applies to both MIPS16 and microMIPS binaries, although for the purpose of this consideration I will focus on the MIPS16 ASE, as well established in our code base now. 2. Statement of the problem To put it shortly, MIPS16 and microMIPS code pointers used by GDB are different to these observed at the run time. This results in the same expressions being evaluated producing different results in GDB and in the program being debugged. Obviously it's the results obtained at the run time that are correct (they define how the program behaves) and therefore by definition the results obtained in GDB are incorrect. A bit longer description will record that obviously at the run time the ISA bit has to be set correctly (refer to background information above if unsure why so) or the program will not run as expected. This is recorded in all the executable file structures used at the run time: the dynamic symbol table (but not always the static one!), the GOT, and obviously in all the addresses embedded in code or data of the program itself, calculated by applying the appropriate relocations at the static link time. While a program is being processed by GDB, the ISA bit is stripped off from any code addresses, presumably to make them the same as the respective raw memory byte address used by the processor to access the instruction in the instruction fetch access cycle. This stripping is actually performed outside GDB proper, in BFD, specifically _bfd_mips_elf_symbol_processing (elfxx-mips.c, see the piece of code at the very bottom of that function, starting with an: "If this is an odd-valued function symbol, assume it's a MIPS16 or microMIPS one." comment). This function is also responsible for symbol table dumps made by `objdump' too, so you'll never see the ISA bit reported there by that tool, you need to use `readelf'. This is however unlike what is ever done at the run time, the ISA bit once present is never stripped off, for example a cast like this: (short *) main will not strip the ISA bit off and if the resulting pointer is intended to be used to access instructions as data, for example for software instruction decoding (like for fault recovery or emulation in a signal handler) or for self-modifying code then the bit still has to be stripped off by an explicit AND operation. This is probably best illustrated with a simple real program example. Let's consider the following simple program: $ cat foobar.c int __attribute__ ((mips16)) foo (void) { return 1; } int __attribute__ ((mips16)) bar (void) { return 2; } int __attribute__ ((nomips16)) foo32 (void) { return 3; } int (*foo32p) (void) = foo32; int (*foop) (void) = foo; int fooi = (int) foo; int main (void) { return foop (); } $ This is plain C with no odd tricks, except from the instruction mode attributes. They are not necessary to trigger this problem, I just put them here so that the program can be contained in a single source file and to make it obvious which function is MIPS16 code and which is not. Let's try it with Linux, so that everyone can repeat this experiment: $ mips-linux-gnu-gcc -mips16 -g -O2 -o foobar foobar.c $ Let's have a look at some interesting symbols: $ mips-linux-gnu-readelf -s foobar | egrep 'table|foo|bar' Symbol table '.dynsym' contains 7 entries: Symbol table '.symtab' contains 95 entries: 55: 00000000 0 FILE LOCAL DEFAULT ABS foobar.c 66: 0040068c 4 FUNC GLOBAL DEFAULT [MIPS16] 12 bar 68: 00410848 4 OBJECT GLOBAL DEFAULT 21 foo32p 70: 00410844 4 OBJECT GLOBAL DEFAULT 21 foop 78: 00400684 8 FUNC GLOBAL DEFAULT 12 foo32 80: 00400680 4 FUNC GLOBAL DEFAULT [MIPS16] 12 foo 88: 00410840 4 OBJECT GLOBAL DEFAULT 21 fooi $ Hmm, no sight of the ISA bit, but notice how foo and bar (but not foo32!) have been marked as MIPS16 functions (ELF symbol structure's st_other field is used for that). So let's try to run and poke at this program with GDB. I'll be using a native system for simplicity (I'll be using ellipses here and there to remove unrelated clutter): $ ./foobar $ echo $? 1 $ So far, so good. $ gdb ./foobar [...] (gdb) break main Breakpoint 1 at 0x400490: file foobar.c, line 23. (gdb) run Starting program: .../foobar Breakpoint 1, main () at foobar.c:23 23 return foop (); (gdb) Yay, it worked! OK, so let's poke at it: (gdb) print main $1 = {int (void)} 0x400490
(gdb) print foo32 $2 = {int (void)} 0x400684 (gdb) print foo32p $3 = (int (*)(void)) 0x400684 (gdb) print bar $4 = {int (void)} 0x40068c (gdb) print foo $5 = {int (void)} 0x400680 (gdb) print foop $6 = (int (*)(void)) 0x400681 (gdb) A-ha! Here's the difference and finally the ISA bit! (gdb) print /x fooi $7 = 0x400681 (gdb) p/x $pc p/x $pc $8 = 0x400491 (gdb) And here as well... (gdb) advance foo foo () at foobar.c:4 4 } (gdb) disassemble Dump of assembler code for function foo: 0x00400680 <+0>: jr ra 0x00400682 <+2>: li v0,1 End of assembler dump. (gdb) finish Run till exit from #0 foo () at foobar.c:4 main () at foobar.c:24 24 } Value returned is $9 = 1 (gdb) continue Continuing. [Inferior 1 (process 14103) exited with code 01] (gdb) So let's be a bit inquisitive... (gdb) run Starting program: .../foobar Breakpoint 1, main () at foobar.c:23 23 return foop (); (gdb) Actually we do not like to run foo here at all. Let's run bar instead! (gdb) set foop = bar (gdb) print foop $10 = (int (*)(void)) 0x40068c (gdb) Hmm, no ISA bit. Is it going to work? (gdb) advance bar bar () at foobar.c:9 9 } (gdb) p/x $pc $11 = 0x40068c (gdb) disassemble Dump of assembler code for function bar: => 0x0040068c <+0>: jr ra 0x0040068e <+2>: li v0,2 End of assembler dump. (gdb) finish Run till exit from #0 bar () at foobar.c:9 Program received signal SIGILL, Illegal instruction. bar () at foobar.c:9 9 } (gdb) Oops! (gdb) p/x $pc $12 = 0x40068c (gdb) We're still there! (gdb) continue Continuing. Program terminated with signal SIGILL, Illegal instruction. The program no longer exists. (gdb) So let's try something else: (gdb) run Starting program: .../foobar Breakpoint 1, main () at foobar.c:23 23 return foop (); (gdb) set foop = foo (gdb) advance foo foo () at foobar.c:4 4 } (gdb) disassemble Dump of assembler code for function foo: => 0x00400680 <+0>: jr ra 0x00400682 <+2>: li v0,1 End of assembler dump. (gdb) finish Run till exit from #0 foo () at foobar.c:4 Program received signal SIGILL, Illegal instruction. foo () at foobar.c:4 4 } (gdb) continue Continuing. Program terminated with signal SIGILL, Illegal instruction. The program no longer exists. (gdb) The same problem! (gdb) run Starting program: /net/build2-lucid-cs/scratch/macro/mips-linux-fsf-gcc/isa-bit/foobar Breakpoint 1, main () at foobar.c:23 23 return foop (); (gdb) set foop = foo32 (gdb) advance foo32 foo32 () at foobar.c:14 14 } (gdb) disassemble Dump of assembler code for function foo32: => 0x00400684 <+0>: jr ra 0x00400688 <+4>: li v0,3 End of assembler dump. (gdb) finish Run till exit from #0 foo32 () at foobar.c:14 main () at foobar.c:24 24 } Value returned is $14 = 3 (gdb) continue Continuing. [Inferior 1 (process 14113) exited with code 03] (gdb) That did work though, so it's the ISA bit only! (gdb) quit Enough! That's the tip of the iceberg only though. So let's rebuild the executable with some dynamic symbols: $ mips-linux-gnu-gcc -mips16 -Wl,--export-dynamic -g -O2 -o foobar-dyn foobar.c $ mips-linux-gnu-readelf -s foobar-dyn | egrep 'table|foo|bar' Symbol table '.dynsym' contains 32 entries: 6: 004009cd 4 FUNC GLOBAL DEFAULT 12 bar 8: 00410b88 4 OBJECT GLOBAL DEFAULT 21 foo32p 9: 00410b84 4 OBJECT GLOBAL DEFAULT 21 foop 15: 004009c4 8 FUNC GLOBAL DEFAULT 12 foo32 17: 004009c1 4 FUNC GLOBAL DEFAULT 12 foo 25: 00410b80 4 OBJECT GLOBAL DEFAULT 21 fooi Symbol table '.symtab' contains 95 entries: 55: 00000000 0 FILE LOCAL DEFAULT ABS foobar.c 69: 004009cd 4 FUNC GLOBAL DEFAULT 12 bar 71: 00410b88 4 OBJECT GLOBAL DEFAULT 21 foo32p 72: 00410b84 4 OBJECT GLOBAL DEFAULT 21 foop 79: 004009c4 8 FUNC GLOBAL DEFAULT 12 foo32 81: 004009c1 4 FUNC GLOBAL DEFAULT 12 foo 89: 00410b80 4 OBJECT GLOBAL DEFAULT 21 fooi $ OK, now the ISA bit is there for a change, but the MIPS16 st_other attribute gone, hmm... What does `objdump' do then: $ mips-linux-gnu-objdump -Tt foobar-dyn | egrep 'SYMBOL|foo|bar' foobar-dyn: file format elf32-tradbigmips SYMBOL TABLE: 00000000 l df *ABS* 00000000 foobar.c 004009cc g F .text 00000004 0xf0 bar 00410b88 g O .data 00000004 foo32p 00410b84 g O .data 00000004 foop 004009c4 g F .text 00000008 foo32 004009c0 g F .text 00000004 0xf0 foo 00410b80 g O .data 00000004 fooi DYNAMIC SYMBOL TABLE: 004009cc g DF .text 00000004 Base 0xf0 bar 00410b88 g DO .data 00000004 Base foo32p 00410b84 g DO .data 00000004 Base foop 004009c4 g DF .text 00000008 Base foo32 004009c0 g DF .text 00000004 Base 0xf0 foo 00410b80 g DO .data 00000004 Base fooi $ Hmm, the attribute (0xf0, printed raw) is back, and the ISA bit gone again. Let's have a look at some DWARF-2 records GDB uses (I'll be stripping off a lot here for brevity) -- debug info: $ mips-linux-gnu-readelf -wi foobar Contents of the .debug_info section: [...] Compilation Unit @ offset 0x88: Length: 0xbb (32-bit) Version: 4 Abbrev Offset: 62 Pointer Size: 4 <0><93>: Abbrev Number: 1 (DW_TAG_compile_unit) <94> DW_AT_producer : (indirect string, offset: 0x19e): GNU C 4.8.0 20120513 (experimental) -meb -mips16 -march=mips32r2 -mhard-float -mllsc -mplt -mno-synci -mno-shared -mabi=32 -g -O2 <98> DW_AT_language : 1 (ANSI C) <99> DW_AT_name : (indirect string, offset: 0x190): foobar.c <9d> DW_AT_comp_dir : (indirect string, offset: 0x225): [...] DW_AT_ranges : 0x0 DW_AT_low_pc : 0x0 DW_AT_stmt_list : 0x27 <1>: Abbrev Number: 2 (DW_TAG_subprogram) DW_AT_external : 1 DW_AT_name : foo DW_AT_decl_file : 1 DW_AT_decl_line : 1 DW_AT_prototyped : 1 DW_AT_type : <0xc2> DW_AT_low_pc : 0x400680 DW_AT_high_pc : 0x400684 DW_AT_frame_base : 1 byte block: 9c (DW_OP_call_frame_cfa) DW_AT_GNU_all_call_sites: 1 <1>: Abbrev Number: 3 (DW_TAG_base_type) DW_AT_byte_size : 4 DW_AT_encoding : 5 (signed) DW_AT_name : int <1>: Abbrev Number: 4 (DW_TAG_subprogram) DW_AT_external : 1 DW_AT_name : (indirect string, offset: 0x18a): foo32 DW_AT_decl_file : 1 DW_AT_decl_line : 11 DW_AT_prototyped : 1 DW_AT_type : <0xc2> DW_AT_low_pc : 0x400684 DW_AT_high_pc : 0x40068c DW_AT_frame_base : 1 byte block: 9c (DW_OP_call_frame_cfa) DW_AT_GNU_all_call_sites: 1 <1>: Abbrev Number: 2 (DW_TAG_subprogram) DW_AT_external : 1 DW_AT_name : bar DW_AT_decl_file : 1 DW_AT_decl_line : 6 DW_AT_prototyped : 1 DW_AT_type : <0xc2> DW_AT_low_pc : 0x40068c DW_AT_high_pc : 0x400690 DW_AT_frame_base : 1 byte block: 9c (DW_OP_call_frame_cfa) DW_AT_GNU_all_call_sites: 1 <1>: Abbrev Number: 5 (DW_TAG_subprogram) DW_AT_external : 1 DW_AT_name : (indirect string, offset: 0x199): main DW_AT_decl_file : 1 DW_AT_decl_line : 21 DW_AT_prototyped : 1 DW_AT_type : <0xc2> DW_AT_low_pc : 0x400490 <102> DW_AT_high_pc : 0x4004a4 <106> DW_AT_frame_base : 1 byte block: 9c (DW_OP_call_frame_cfa) <108> DW_AT_GNU_all_tail_call_sites: 1 [...] $ -- no sign of the ISA bit anywhere -- frame info: $ mips-linux-gnu-readelf -wf foobar [...] Contents of the .debug_frame section: 00000000 0000000c ffffffff CIE Version: 1 Augmentation: "" Code alignment factor: 1 Data alignment factor: -4 Return address column: 31 DW_CFA_def_cfa_register: r29 DW_CFA_nop 00000010 0000000c 00000000 FDE cie=00000000 pc=00400680..00400684 00000020 0000000c 00000000 FDE cie=00000000 pc=00400684..0040068c 00000030 0000000c 00000000 FDE cie=00000000 pc=0040068c..00400690 00000040 00000018 00000000 FDE cie=00000000 pc=00400490..004004a4 DW_CFA_advance_loc: 6 to 00400496 DW_CFA_def_cfa_offset: 32 DW_CFA_offset: r31 at cfa-4 DW_CFA_advance_loc: 6 to 0040049c DW_CFA_restore: r31 DW_CFA_def_cfa_offset: 0 DW_CFA_nop DW_CFA_nop DW_CFA_nop [...] $ -- no sign of the ISA bit anywhere -- range info (GDB doesn't use arange): $ mips-linux-gnu-readelf -wR foobar Contents of the .debug_ranges section: Offset Begin End 00000000 00400680 00400690 00000000 00400490 004004a4 00000000 $ -- no sign of the ISA bit anywhere -- line info: $ mips-linux-gnu-readelf -wl foobar Raw dump of debug contents of section .debug_line: [...] Offset: 0x27 Length: 78 DWARF Version: 2 Prologue Length: 31 Minimum Instruction Length: 1 Initial value of 'is_stmt': 1 Line Base: -5 Line Range: 14 Opcode Base: 13 Opcodes: Opcode 1 has 0 args Opcode 2 has 1 args Opcode 3 has 1 args Opcode 4 has 1 args Opcode 5 has 1 args Opcode 6 has 0 args Opcode 7 has 0 args Opcode 8 has 0 args Opcode 9 has 1 args Opcode 10 has 0 args Opcode 11 has 0 args Opcode 12 has 1 args The Directory Table is empty. The File Name Table: Entry Dir Time Size Name 1 0 0 0 foobar.c Line Number Statements: Extended opcode 2: set Address to 0x400681 Special opcode 6: advance Address by 0 to 0x400681 and Line by 1 to 2 Special opcode 7: advance Address by 0 to 0x400681 and Line by 2 to 4 Special opcode 55: advance Address by 3 to 0x400684 and Line by 8 to 12 Special opcode 7: advance Address by 0 to 0x400684 and Line by 2 to 14 Advance Line by -7 to 7 Special opcode 131: advance Address by 9 to 0x40068d and Line by 0 to 7 Special opcode 7: advance Address by 0 to 0x40068d and Line by 2 to 9 Advance PC by 3 to 0x400690 Extended opcode 1: End of Sequence Extended opcode 2: set Address to 0x400491 Advance Line by 21 to 22 Copy Special opcode 6: advance Address by 0 to 0x400491 and Line by 1 to 23 Special opcode 60: advance Address by 4 to 0x400495 and Line by -1 to 22 Special opcode 34: advance Address by 2 to 0x400497 and Line by 1 to 23 Special opcode 62: advance Address by 4 to 0x40049b and Line by 1 to 24 Special opcode 32: advance Address by 2 to 0x40049d and Line by -1 to 23 Special opcode 6: advance Address by 0 to 0x40049d and Line by 1 to 24 Advance PC by 7 to 0x4004a4 Extended opcode 1: End of Sequence [...] -- a-ha, the ISA bit is there! However it's not always right for some reason, I don't have a small test case to show it, but here's an excerpt from MIPS16 libc, a prologue of a function: 00019630 <__libc_init_first>: 19630: e8a0 jrc ra 19632: 6500 nop 00019634 <_init>: 19634: f000 6a11 li v0,17 19638: f7d8 0b08 la v1,15e00 <_DYNAMIC+0x15c54> 1963c: f400 3240 sll v0,16 19640: e269 addu v0,v1 19642: 659a move gp,v0 19644: 64f6 save 48,ra,s0-s1 19646: 671c move s0,gp 19648: d204 sw v0,16(sp) 1964a: f352 984c lw v0,-27828(s0) 1964e: 6724 move s1,a0 and the corresponding DWARF-2 line info: Line Number Statements: Extended opcode 2: set Address to 0x19631 Advance Line by 44 to 45 Copy Special opcode 8: advance Address by 0 to 0x19631 and Line by 3 to 48 Special opcode 66: advance Address by 4 to 0x19635 and Line by 5 to 53 Advance PC by constant 17 to 0x19646 Special opcode 25: advance Address by 1 to 0x19647 and Line by 6 to 59 Advance Line by -6 to 53 Special opcode 33: advance Address by 2 to 0x19649 and Line by 0 to 53 Special opcode 39: advance Address by 2 to 0x1964b and Line by 6 to 59 Advance Line by -6 to 53 Special opcode 61: advance Address by 4 to 0x1964f and Line by 0 to 53 -- see that "Advance PC by constant 17" there? It clears the ISA bit, however code at 0x19646 is not standard MIPS code at all. For some reason the constant is always 17, I've never seen DW_LNS_const_add_pc used with any other value -- is that a binutils bug or what? 3. Proposed solution: I think we should retain the value of the ISA bit in code references, that is effectively treat them as cookies as they indeed are (although trivially calculated) rather than raw memory byte addresses. In a perfect world both the static symbol table and the respective DWARF-2 records should be fixed to include the ISA bit in all the cases. I think however that this is infeasible. All the uses of _bfd_mips_elf_symbol_processing can not necessarily be tracked down. This function is used by elf_slurp_symbol_table that in turn is used by bfd_canonicalize_symtab and bfd_canonicalize_dynamic_symtab, which are public interfaces. Similarly DWARF-2 records are used outside GDB, one notable if a bit questionable is the exception unwinder (libgcc/unwind-dw2.c) -- I have identified at least bits in execute_cfa_program and uw_frame_state_for, both around the calls to _Unwind_IsSignalFrame, that would need an update as they effectively flip the ISA bit freely; see also the comment about MASK_RETURN_ADDR in gcc/config/mips/mips.h. But there may be more places. Any change in how DWARF-2 records are produced would require an update there and would cause compatibility problems with libgcc.a binaries already distributed; given that this is a static library a complex change involving function renames would likely be required. I propose therefore to accept the existing inconsistencies and deal with them entirely within GDB. I have figured out that the ISA bit lost in various places can still be recovered as long as we have symbol information -- that'll have the st_other attribute correctly set to one of standard MIPS/MIPS16/microMIPS. Here's the resulting change. It adds a couple of new gdbarch hooks, one to update symbol information with the ISA bit lost in _bfd_mips_elf_symbol_processing, and two other ones to adjust DWARF-2 records as they're processed. I have figured out only FDE addresses, line information and ranges need to be adjusted; CFA records in particular are FDE-relative and therefore work "automagically" after these adjustments. The ISA bit is set in each address handled according to information retrieved from the symbol table for the symbol spanning the address if any; limits are adjusted based on the address they point to related to the respective base address. Additionally minimal symbol information has to be adjusted accordingly in its gdbarch hook. With these changes in place some complications with ISA bit juggling in the PC that never fully worked can be removed from the MIPS backend. Conversely, the generic dynamic linker event special breakpoint symbol handler has to be updated to call the minimal symbol gdbarch hook to record that the symbol is a MIPS16 or microMIPS address if applicable or the breakpoint will be set at the wrong address and either fail to work or cause SIGTRAPs (this is because the symbol is handled early on and bypasses regular symbol processing). 4. Results obtained The change fixes the example above -- to repeat only the crucial steps: (gdb) break main Breakpoint 1 at 0x400491: file foobar.c, line 23. (gdb) run Starting program: .../foobar Breakpoint 1, main () at foobar.c:23 23 return foop (); (gdb) print foo $1 = {int (void)} 0x400681 (gdb) set foop = bar (gdb) advance bar bar () at foobar.c:9 9 } (gdb) disassemble Dump of assembler code for function bar: => 0x0040068d <+0>: jr ra 0x0040068f <+2>: li v0,2 End of assembler dump. (gdb) finish Run till exit from #0 bar () at foobar.c:9 main () at foobar.c:24 24 } Value returned is $2 = 2 (gdb) continue Continuing. [Inferior 1 (process 14128) exited with code 02] (gdb) -- excellent! The change removes about 90 failures per MIPS16 multilib in mips-sde-elf testing too, results for MIPS16 are now similar to that for standard MIPS; microMIPS results are a bit worse because of host-I/O problems in QEMU I use for microMIPS only: standard MIPS: === gdb Summary === # of expected passes 14299 # of unexpected failures 187 # of expected failures 56 # of known failures 58 # of unresolved testcases 11 # of untested testcases 52 # of unsupported tests 174 MIPS16: === gdb Summary === # of expected passes 14298 # of unexpected failures 187 # of unexpected successes 2 # of expected failures 54 # of known failures 58 # of unresolved testcases 12 # of untested testcases 52 # of unsupported tests 174 microMIPS: === gdb Summary === # of expected passes 14149 # of unexpected failures 201 # of unexpected successes 2 # of expected failures 54 # of known failures 58 # of unresolved testcases 7 # of untested testcases 53 # of unsupported tests 175 I'll be rerunning mips-linux-gnu testing as the results I have got turned out questionable, so I need to double-check. I'll post them when I have them ready. This change regresses five cases too: gdb.cp/cp-relocate.exp: print caller $3 = {int (void)} 0x1 (gdb) FAIL: gdb.cp/cp-relocate.exp: get address of caller and gdb.cp/expand-psymtabs-cxx.exp: p 'method(long)' $1 = {void (long)} 0x1 (gdb) FAIL: gdb.cp/expand-psymtabs-cxx.exp: before expand p method $2 = {void (long)} 0x1 (gdb) FAIL: gdb.cp/expand-psymtabs-cxx.exp: force expand p 'method(long)' $3 = {void (long)} 0x1 (gdb) FAIL: gdb.cp/expand-psymtabs-cxx.exp: after expand -- the two above are clearly test case bugs -- they load relocatables into GDB and shouldn't really require unlinked symbol references to resolve as NULLs, they probably just need to be fixed to accept output produced above too. gdb.dwarf2/dw2-empty-pc-range.exp: No symbol "realrange" in current context. (gdb) FAIL: gdb.dwarf2/dw2-empty-pc-range.exp: valid range after CU load -- this test uses this source: pc_start: .byte 0 pc_end: which flips the ISA bit on pc_end as a side effect. This bit is (IMO) correctly cleared in processing with my change making the instruction range between pc_start and pc_end empty; I'd be just tempted to change .byte into .word or suchlike, the exact size does not matter for this test and I think the space requested above should not be smaller than the (smallest) instruction size on any target. gdb.dwarf2/dw2-skip-prologue.exp: continue Continuing. Program received signal SIGBUS, Bus error. 0x004006fb in main () (gdb) FAIL: gdb.dwarf2/dw2-skip-prologue.exp: continue to breakpoint: func info break $bpnum Num Type Disp Enb Address What 2 breakpoint keep y 2.1 y 0x00400671 in func at main.c:5 2.2 y 0x004006ac (gdb) PASS: gdb.dwarf2/dw2-skip-prologue.exp: 2 locations found p v $1 = 8 (gdb) FAIL: gdb.dwarf2/dw2-skip-prologue.exp: no statement got executed -- this is plain bogus, the test strips symbol information for fund that is a MIPS16 function at 0x004006ad, the data required is permanently lost and the incorrect software breakpoint instruction encoding used caused execution to go into the weed (this only regresses on simulators that pretend to use hardware breakpoints and disregard the ISA bit; for any other target the test didn't work anyway). I don't know how to fix the test and retain functionality covered; this has to be rethought and reimplemented differently I would say. 5. Conclusion As noted at the beginning I am looking forward to all feedback to this proposal. I'm working on a small proper test case for our test suite to cover the function pointer issues shown above. Maciej 2012-05-14 Maciej W. Rozycki Maciej W. Rozycki Pedro Alves * gdbarch.sh (make_symbol_special): New architecture method. (adjust_dwarf2_addr, adjust_dwarf2_line): Likewise. (objfile, symbol): New declarations. * arch-utils.h (default_make_symbol_special): New prototype. (default_adjust_dwarf2_addr): Likewise. (default_adjust_dwarf2_line): Likewise. * arch-utils.c (default_make_symbol_special): New function. * dwarf2-frame.c (decode_frame_entry_1): Call gdbarch_adjust_dwarf2_addr. * dwarf2loc.c (dwarf2_find_location_expression): Likewise. * dwarf2read.c (read_func_scope): Call gdbarch_make_symbol_special. (dwarf2_ranges_read): Call gdbarch_adjust_dwarf2_addr. (read_attribute_value): Likewise. (dwarf_decode_lines_1): Call gdbarch_adjust_dwarf2_line. * mips-tdep.c (mips_elf_make_msymbol_special): Set the ISA bit in the symbol's address appropriately. (mips_make_symbol_special): New function. (mips_pc_is_mips): Set the ISA bit before symbol lookup. (mips_pc_is_mips16): Likewise. (mips_pc_is_micromips): Likewise. (mips_pc_isa): Likewise. (mips_adjust_dwarf2_addr): New function. (mips_adjust_dwarf2_line): Likewise. (mips_read_pc, mips_unwind_pc): Keep the ISA bit. (mips_addr_bits_remove): Likewise. (mips_skip_trampoline_code): Likewise. (mips_write_pc): Don't set the ISA bit. (mips_eabi_push_dummy_call): Likewise. (mips_o64_push_dummy_call): Likewise. (mips_gdbarch_init): Install mips_make_symbol_special, mips_adjust_dwarf2_addr and mips_adjust_dwarf2_line gdbarch handlers. * solib.c (gdb_bfd_lookup_symbol_from_symtab): Get target-specific symbol address adjustments. * gdbarch.h: Regenerate. * gdbarch.c: Regenerate. gdb-mips16-isa-bit.diff Index: gdb-fsf-trunk-quilt/gdb/mips-tdep.c =================================================================== --- gdb-fsf-trunk-quilt.orig/gdb/mips-tdep.c 2012-05-14 16:00:33.000000000 +0100 +++ gdb-fsf-trunk-quilt/gdb/mips-tdep.c 2012-05-14 16:02:02.235560558 +0100 @@ -358,9 +358,15 @@ mips_elf_make_msymbol_special (asymbol * return; if (ELF_ST_IS_MICROMIPS (elfsym->internal_elf_sym.st_other)) - MSYMBOL_TARGET_FLAG_2 (msym) = 1; + { + MSYMBOL_TARGET_FLAG_2 (msym) = 1; + SYMBOL_VALUE_ADDRESS (msym) |= 1; + } else if (ELF_ST_IS_MIPS16 (elfsym->internal_elf_sym.st_other)) - MSYMBOL_TARGET_FLAG_1 (msym) = 1; + { + MSYMBOL_TARGET_FLAG_1 (msym) = 1; + SYMBOL_VALUE_ADDRESS (msym) |= 1; + } } /* Return one iff MSYM refers to standard ISA code. */ @@ -387,6 +393,24 @@ msymbol_is_micromips (struct minimal_sym return MSYMBOL_TARGET_FLAG_2 (msym); } +/* Set the ISA bit in the main symbol too, complementing the corresponding + minimal symbol setting and reflecting the run-time value of the symbol. */ + +static void +mips_make_symbol_special (struct symbol *sym, struct objfile *objfile) +{ + if (SYMBOL_CLASS (sym) == LOC_BLOCK) + { + CORE_ADDR compact_block_start; + struct minimal_symbol *msym; + + compact_block_start = BLOCK_START (SYMBOL_BLOCK_VALUE (sym)) | 1; + msym = lookup_minimal_symbol_by_pc (compact_block_start); + if (msym && !msymbol_is_mips (msym)) + BLOCK_START (SYMBOL_BLOCK_VALUE (sym)) = compact_block_start; + } +} + /* XFER a value from the big/little/left end of the register. Depending on the size of the value it might occupy the entire register or just part of it. Make an allowance for this, aligning @@ -1123,7 +1147,7 @@ mips_pc_is_mips (CORE_ADDR memaddr) stored by elfread.c in the high bit of the info field. Use this to decide if the function is standard MIPS. Otherwise if bit 0 of the address is clear, then this is a standard MIPS function. */ - sym = lookup_minimal_symbol_by_pc (memaddr); + sym = lookup_minimal_symbol_by_pc (make_compact_addr (memaddr)); if (sym) return msymbol_is_mips (sym); else @@ -1141,7 +1165,7 @@ mips_pc_is_mips16 (struct gdbarch *gdbar elfread.c in the high bit of the info field. Use this to decide if the function is MIPS16. Otherwise if bit 0 of the address is set, then ELF file flags will tell if this is a MIPS16 function. */ - sym = lookup_minimal_symbol_by_pc (memaddr); + sym = lookup_minimal_symbol_by_pc (make_compact_addr (memaddr)); if (sym) return msymbol_is_mips16 (sym); else @@ -1160,7 +1184,7 @@ mips_pc_is_micromips (struct gdbarch *gd if the function is microMIPS. Otherwise if bit 0 of the address is set, then ELF file flags will tell if this is a microMIPS function. */ - sym = lookup_minimal_symbol_by_pc (memaddr); + sym = lookup_minimal_symbol_by_pc (make_compact_addr (memaddr)); if (sym) return msymbol_is_micromips (sym); else @@ -1180,7 +1204,7 @@ mips_pc_isa (struct gdbarch *gdbarch, CO this to decide if the function is MIPS16 or microMIPS or normal MIPS. Otherwise if bit 0 of the address is set, then ELF file flags will tell if this is a MIPS16 or a microMIPS function. */ - sym = lookup_minimal_symbol_by_pc (memaddr); + sym = lookup_minimal_symbol_by_pc (make_compact_addr (memaddr)); if (sym) { if (msymbol_is_micromips (sym)) @@ -1201,6 +1225,32 @@ mips_pc_isa (struct gdbarch *gdbarch, CO } } +/* Set the ISA bit correctly in the PC, used by DWARF-2 machinery. */ + +static CORE_ADDR +mips_adjust_dwarf2_addr (CORE_ADDR pc) +{ + pc = unmake_compact_addr (pc); + return mips_pc_is_mips (pc) ? pc : make_compact_addr (pc); +} + +/* Recalculate the line record requested so that the resulting PC has the + ISA bit set correctly, used by DWARF-2 machinery. */ + +static CORE_ADDR +mips_adjust_dwarf2_line (CORE_ADDR addr, int rel) +{ + static CORE_ADDR adj_pc; + static CORE_ADDR pc; + CORE_ADDR isa_pc; + + pc = rel ? pc + addr : addr; + isa_pc = mips_adjust_dwarf2_addr (pc); + addr = rel ? isa_pc - adj_pc : isa_pc; + adj_pc = isa_pc; + return addr; +} + /* Various MIPS16 thunk (aka stub or trampoline) names. */ static const char mips_str_mips16_call_stub[] = "__mips16_call_stub_"; @@ -1249,8 +1299,6 @@ mips_read_pc (struct regcache *regcache) ULONGEST pc; int regnum = mips_regnum (get_regcache_arch (regcache))->pc; regcache_cooked_read_signed (regcache, regnum, &pc); - if (is_compact_addr (pc)) - pc = unmake_compact_addr (pc); return pc; } @@ -1261,8 +1309,6 @@ mips_unwind_pc (struct gdbarch *gdbarch, pc = frame_unwind_register_signed (next_frame, gdbarch_num_regs (gdbarch) + mips_regnum (gdbarch)->pc); - if (is_compact_addr (pc)) - pc = unmake_compact_addr (pc); /* macro/2012-04-20: This hack skips over MIPS16 call thunks as intermediate frames. In this case we can get the caller's address from $ra, or if $ra contains an address within a thunk as well, then @@ -1272,15 +1318,9 @@ mips_unwind_pc (struct gdbarch *gdbarch, { pc = frame_unwind_register_signed (next_frame, gdbarch_num_regs (gdbarch) + MIPS_RA_REGNUM); - if (is_compact_addr (pc)) - pc = unmake_compact_addr (pc); if (mips_in_frame_stub (pc)) - { - pc = frame_unwind_register_signed - (next_frame, gdbarch_num_regs (gdbarch) + MIPS_S2_REGNUM); - if (is_compact_addr (pc)) - pc = unmake_compact_addr (pc); - } + pc = frame_unwind_register_signed + (next_frame, gdbarch_num_regs (gdbarch) + MIPS_S2_REGNUM); } return pc; } @@ -1312,10 +1352,7 @@ mips_write_pc (struct regcache *regcache { int regnum = mips_regnum (get_regcache_arch (regcache))->pc; - if (mips_pc_is_mips (pc)) - regcache_cooked_write_unsigned (regcache, regnum, pc); - else - regcache_cooked_write_unsigned (regcache, regnum, make_compact_addr (pc)); + regcache_cooked_write_unsigned (regcache, regnum, pc); } /* Fetch and return instruction from the specified location. Handle @@ -3603,10 +3640,6 @@ static CORE_ADDR mips_addr_bits_remove (struct gdbarch *gdbarch, CORE_ADDR addr) { struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch); - - if (is_compact_addr (addr)) - addr = unmake_compact_addr (addr); - if (mips_mask_address_p (tdep) && (((ULONGEST) addr) >> 32 == 0xffffffffUL)) /* This hack is a work-around for existing boards using PMON, the simulator, and any other 64-bit targets that doesn't have true @@ -4298,25 +4331,9 @@ mips_eabi_push_dummy_call (struct gdbarc "mips_eabi_push_dummy_call: %d len=%d type=%d", argnum + 1, len, (int) typecode); - /* Function pointer arguments to mips16 code need to be made into - mips16 pointers. */ - if (typecode == TYPE_CODE_PTR - && TYPE_CODE (TYPE_TARGET_TYPE (arg_type)) == TYPE_CODE_FUNC) - { - CORE_ADDR addr = extract_signed_integer (value_contents (arg), - len, byte_order); - if (mips_pc_is_mips (addr)) - val = value_contents (arg); - else - { - store_signed_integer (valbuf, len, byte_order, - make_compact_addr (addr)); - val = valbuf; - } - } /* The EABI passes structures that do not fit in a register by reference. */ - else if (len > regsize + if (len > regsize && (typecode == TYPE_CODE_STRUCT || typecode == TYPE_CODE_UNION)) { store_unsigned_integer (valbuf, regsize, byte_order, @@ -5686,7 +5703,6 @@ mips_o64_push_dummy_call (struct gdbarch for (argnum = 0; argnum < nargs; argnum++) { const gdb_byte *val; - gdb_byte valbuf[MAX_REGISTER_SIZE]; struct value *arg = args[argnum]; struct type *arg_type = check_typedef (value_type (arg)); int len = TYPE_LENGTH (arg_type); @@ -5699,21 +5715,6 @@ mips_o64_push_dummy_call (struct gdbarch val = value_contents (arg); - /* Function pointer arguments to mips16 code need to be made into - mips16 pointers. */ - if (typecode == TYPE_CODE_PTR - && TYPE_CODE (TYPE_TARGET_TYPE (arg_type)) == TYPE_CODE_FUNC) - { - CORE_ADDR addr = extract_signed_integer (value_contents (arg), - len, byte_order); - if (!mips_pc_is_mips (addr)) - { - store_signed_integer (valbuf, len, byte_order, - make_compact_addr (addr)); - val = valbuf; - } - } - /* Floating point arguments passed in registers have to be treated specially. On 32-bit architectures, doubles are passed in register pairs; the even FP register gets the @@ -7637,27 +7638,15 @@ mips_skip_trampoline_code (struct frame_ new_pc = mips_skip_mips16_trampoline_code (frame, pc); if (new_pc) - { - pc = new_pc; - if (is_compact_addr (pc)) - pc = unmake_compact_addr (pc); - } + pc = new_pc; new_pc = find_solib_trampoline_target (frame, pc); if (new_pc) - { - pc = new_pc; - if (is_compact_addr (pc)) - pc = unmake_compact_addr (pc); - } + pc = new_pc; new_pc = mips_skip_pic_trampoline_code (frame, pc); if (new_pc) - { - pc = new_pc; - if (is_compact_addr (pc)) - pc = unmake_compact_addr (pc); - } + pc = new_pc; } while (pc != target_pc); @@ -8315,6 +8304,9 @@ mips_gdbarch_init (struct gdbarch_info i set_gdbarch_elf_make_msymbol_special (gdbarch, mips_elf_make_msymbol_special); + set_gdbarch_make_symbol_special (gdbarch, mips_make_symbol_special); + set_gdbarch_adjust_dwarf2_addr (gdbarch, mips_adjust_dwarf2_addr); + set_gdbarch_adjust_dwarf2_line (gdbarch, mips_adjust_dwarf2_line); regnum = GDBARCH_OBSTACK_ZALLOC (gdbarch, struct mips_regnum); *regnum = mips_regnum; Index: gdb-fsf-trunk-quilt/gdb/arch-utils.c =================================================================== --- gdb-fsf-trunk-quilt.orig/gdb/arch-utils.c 2012-05-14 15:56:47.000000000 +0100 +++ gdb-fsf-trunk-quilt/gdb/arch-utils.c 2012-05-14 16:02:02.205560708 +0100 @@ -31,6 +31,7 @@ #include "osabi.h" #include "target-descriptions.h" #include "objfiles.h" +#include "symtab.h" #include "version.h" @@ -178,6 +179,24 @@ default_coff_make_msymbol_special (int v return; } +void +default_make_symbol_special (struct symbol *sym, struct objfile *objfile) +{ + return; +} + +CORE_ADDR +default_adjust_dwarf2_addr (CORE_ADDR pc) +{ + return pc; +} + +CORE_ADDR +default_adjust_dwarf2_line (CORE_ADDR addr, int rel) +{ + return addr; +} + int cannot_register_not (struct gdbarch *gdbarch, int regnum) { Index: gdb-fsf-trunk-quilt/gdb/arch-utils.h =================================================================== --- gdb-fsf-trunk-quilt.orig/gdb/arch-utils.h 2012-05-14 15:56:47.000000000 +0100 +++ gdb-fsf-trunk-quilt/gdb/arch-utils.h 2012-05-14 16:02:02.235560558 +0100 @@ -81,6 +81,18 @@ void default_elf_make_msymbol_special (a void default_coff_make_msymbol_special (int val, struct minimal_symbol *msym); +/* Do nothing version of make_symbol_special. */ + +void default_make_symbol_special (struct symbol *sym, struct objfile *objfile); + +/* Do nothing version of adjust_dwarf2_addr. */ + +CORE_ADDR default_adjust_dwarf2_addr (CORE_ADDR pc); + +/* Do nothing version of adjust_dwarf2_line. */ + +CORE_ADDR default_adjust_dwarf2_line (CORE_ADDR addr, int rel); + /* Version of cannot_fetch_register() / cannot_store_register() that always fails. */ Index: gdb-fsf-trunk-quilt/gdb/dwarf2read.c =================================================================== --- gdb-fsf-trunk-quilt.orig/gdb/dwarf2read.c 2012-05-14 15:56:47.000000000 +0100 +++ gdb-fsf-trunk-quilt/gdb/dwarf2read.c 2012-05-14 16:02:02.245560384 +0100 @@ -7328,6 +7328,7 @@ static void read_func_scope (struct die_info *die, struct dwarf2_cu *cu) { struct objfile *objfile = cu->objfile; + struct gdbarch *gdbarch = get_objfile_arch (objfile); struct context_stack *new; CORE_ADDR lowpc; CORE_ADDR highpc; @@ -7478,6 +7479,8 @@ read_func_scope (struct die_info *die, s /* If we have address ranges, record them. */ dwarf2_record_block_ranges (die, block, baseaddr, cu); + gdbarch_make_symbol_special (gdbarch, new->name, objfile); + /* Attach template arguments to function. */ if (! VEC_empty (symbolp, template_args)) { @@ -7827,6 +7830,7 @@ dwarf2_ranges_read (unsigned offset, COR struct partial_symtab *ranges_pst) { struct objfile *objfile = cu->objfile; + struct gdbarch *gdbarch = get_objfile_arch (objfile); struct comp_unit_head *cu_header = &cu->header; bfd *obfd = objfile->obfd; unsigned int addr_size = cu_header->addr_size; @@ -7922,6 +7926,9 @@ dwarf2_ranges_read (unsigned offset, COR range_beginning += base; range_end += base; + range_beginning = gdbarch_adjust_dwarf2_addr (gdbarch, range_beginning); + range_end = gdbarch_adjust_dwarf2_addr (gdbarch, range_end); + if (ranges_pst != NULL) addrmap_set_empty (objfile->psymtabs_addrmap, range_beginning + baseaddr, @@ -11552,6 +11559,8 @@ read_attribute_value (const struct die_r gdb_byte *info_ptr) { struct dwarf2_cu *cu = reader->cu; + struct objfile *objfile = cu->objfile; + struct gdbarch *gdbarch = get_objfile_arch (objfile); bfd *abfd = reader->abfd; struct comp_unit_head *cu_header = &cu->header; unsigned int bytes_read; @@ -11570,6 +11579,7 @@ read_attribute_value (const struct die_r break; case DW_FORM_addr: DW_ADDR (attr) = read_address (abfd, info_ptr, cu, &bytes_read); + DW_ADDR (attr) = gdbarch_adjust_dwarf2_addr (gdbarch, DW_ADDR (attr)); info_ptr += bytes_read; break; case DW_FORM_block2: @@ -12767,7 +12777,7 @@ dwarf_decode_lines_1 (struct line_header while (line_ptr < line_end) { /* state machine registers */ - CORE_ADDR address = 0; + CORE_ADDR address = gdbarch_adjust_dwarf2_line (gdbarch, 0, 0); unsigned int file = 1; unsigned int line = 1; unsigned int column = 0; @@ -12805,11 +12815,14 @@ dwarf_decode_lines_1 (struct line_header if (op_code >= lh->opcode_base) { + CORE_ADDR addr_adj; + /* Special operand. */ adj_opcode = op_code - lh->opcode_base; - address += (((op_index + (adj_opcode / lh->line_range)) + addr_adj = (((op_index + (adj_opcode / lh->line_range)) / lh->maximum_ops_per_instruction) * lh->minimum_instruction_length); + address += gdbarch_adjust_dwarf2_line (gdbarch, addr_adj, 1); op_index = ((op_index + (adj_opcode / lh->line_range)) % lh->maximum_ops_per_instruction); line += lh->line_base + (adj_opcode % lh->line_range); @@ -12872,6 +12885,7 @@ dwarf_decode_lines_1 (struct line_header op_index = 0; line_ptr += bytes_read; address += baseaddr; + address = gdbarch_adjust_dwarf2_line (gdbarch, address, 0); break; case DW_LNE_define_file: { @@ -12938,10 +12952,12 @@ dwarf_decode_lines_1 (struct line_header { CORE_ADDR adjust = read_unsigned_leb128 (abfd, line_ptr, &bytes_read); + CORE_ADDR addr_adj; - address += (((op_index + adjust) + addr_adj = (((op_index + adjust) / lh->maximum_ops_per_instruction) * lh->minimum_instruction_length); + address += gdbarch_adjust_dwarf2_line (gdbarch, addr_adj, 1); op_index = ((op_index + adjust) % lh->maximum_ops_per_instruction); line_ptr += bytes_read; @@ -12994,18 +13010,25 @@ dwarf_decode_lines_1 (struct line_header case DW_LNS_const_add_pc: { CORE_ADDR adjust = (255 - lh->opcode_base) / lh->line_range; + CORE_ADDR addr_adj; - address += (((op_index + adjust) + addr_adj = (((op_index + adjust) / lh->maximum_ops_per_instruction) * lh->minimum_instruction_length); + address += gdbarch_adjust_dwarf2_line (gdbarch, addr_adj, 1); op_index = ((op_index + adjust) % lh->maximum_ops_per_instruction); } break; case DW_LNS_fixed_advance_pc: - address += read_2_bytes (abfd, line_ptr); - op_index = 0; - line_ptr += 2; + { + CORE_ADDR addr_adj; + + addr_adj = read_2_bytes (abfd, line_ptr); + address += gdbarch_adjust_dwarf2_line (gdbarch, addr_adj, 1); + op_index = 0; + line_ptr += 2; + } break; default: { Index: gdb-fsf-trunk-quilt/gdb/gdbarch.c =================================================================== --- gdb-fsf-trunk-quilt.orig/gdb/gdbarch.c 2012-05-14 15:56:47.000000000 +0100 +++ gdb-fsf-trunk-quilt/gdb/gdbarch.c 2012-05-14 16:02:02.205560708 +0100 @@ -230,6 +230,9 @@ struct gdbarch gdbarch_in_function_epilogue_p_ftype *in_function_epilogue_p; gdbarch_elf_make_msymbol_special_ftype *elf_make_msymbol_special; gdbarch_coff_make_msymbol_special_ftype *coff_make_msymbol_special; + gdbarch_make_symbol_special_ftype *make_symbol_special; + gdbarch_adjust_dwarf2_addr_ftype *adjust_dwarf2_addr; + gdbarch_adjust_dwarf2_line_ftype *adjust_dwarf2_line; int cannot_step_breakpoint; int have_nonsteppable_watchpoint; gdbarch_address_class_type_flags_ftype *address_class_type_flags; @@ -398,6 +401,9 @@ struct gdbarch startup_gdbarch = generic_in_function_epilogue_p, /* in_function_epilogue_p */ 0, /* elf_make_msymbol_special */ 0, /* coff_make_msymbol_special */ + 0, /* make_symbol_special */ + 0, /* adjust_dwarf2_addr */ + 0, /* adjust_dwarf2_line */ 0, /* cannot_step_breakpoint */ 0, /* have_nonsteppable_watchpoint */ 0, /* address_class_type_flags */ @@ -532,6 +538,9 @@ gdbarch_alloc (const struct gdbarch_info gdbarch->in_function_epilogue_p = generic_in_function_epilogue_p; gdbarch->elf_make_msymbol_special = default_elf_make_msymbol_special; gdbarch->coff_make_msymbol_special = default_coff_make_msymbol_special; + gdbarch->make_symbol_special = default_make_symbol_special; + gdbarch->adjust_dwarf2_addr = default_adjust_dwarf2_addr; + gdbarch->adjust_dwarf2_line = default_adjust_dwarf2_line; gdbarch->register_reggroup_p = default_register_reggroup_p; gdbarch->displaced_step_hw_singlestep = default_displaced_step_hw_singlestep; gdbarch->displaced_step_fixup = NULL; @@ -699,6 +708,9 @@ verify_gdbarch (struct gdbarch *gdbarch) /* Skip verify of in_function_epilogue_p, invalid_p == 0 */ /* Skip verify of elf_make_msymbol_special, invalid_p == 0 */ /* Skip verify of coff_make_msymbol_special, invalid_p == 0 */ + /* Skip verify of make_symbol_special, invalid_p == 0 */ + /* Skip verify of adjust_dwarf2_addr, invalid_p == 0 */ + /* Skip verify of adjust_dwarf2_line, invalid_p == 0 */ /* Skip verify of cannot_step_breakpoint, invalid_p == 0 */ /* Skip verify of have_nonsteppable_watchpoint, invalid_p == 0 */ /* Skip verify of address_class_type_flags, has predicate. */ @@ -811,6 +823,12 @@ gdbarch_dump (struct gdbarch *gdbarch, s "gdbarch_dump: adjust_breakpoint_address = <%s>\n", host_address_to_string (gdbarch->adjust_breakpoint_address)); fprintf_unfiltered (file, + "gdbarch_dump: adjust_dwarf2_addr = <%s>\n", + host_address_to_string (gdbarch->adjust_dwarf2_addr)); + fprintf_unfiltered (file, + "gdbarch_dump: adjust_dwarf2_line = <%s>\n", + host_address_to_string (gdbarch->adjust_dwarf2_line)); + fprintf_unfiltered (file, "gdbarch_dump: auto_charset = <%s>\n", host_address_to_string (gdbarch->auto_charset)); fprintf_unfiltered (file, @@ -1087,6 +1105,9 @@ gdbarch_dump (struct gdbarch *gdbarch, s "gdbarch_dump: make_corefile_notes = <%s>\n", host_address_to_string (gdbarch->make_corefile_notes)); fprintf_unfiltered (file, + "gdbarch_dump: make_symbol_special = <%s>\n", + host_address_to_string (gdbarch->make_symbol_special)); + fprintf_unfiltered (file, "gdbarch_dump: gdbarch_max_insn_length_p() = %d\n", gdbarch_max_insn_length_p (gdbarch)); fprintf_unfiltered (file, @@ -3141,6 +3162,57 @@ set_gdbarch_coff_make_msymbol_special (s gdbarch->coff_make_msymbol_special = coff_make_msymbol_special; } +void +gdbarch_make_symbol_special (struct gdbarch *gdbarch, struct symbol *sym, struct objfile *objfile) +{ + gdb_assert (gdbarch != NULL); + gdb_assert (gdbarch->make_symbol_special != NULL); + if (gdbarch_debug >= 2) + fprintf_unfiltered (gdb_stdlog, "gdbarch_make_symbol_special called\n"); + gdbarch->make_symbol_special (sym, objfile); +} + +void +set_gdbarch_make_symbol_special (struct gdbarch *gdbarch, + gdbarch_make_symbol_special_ftype make_symbol_special) +{ + gdbarch->make_symbol_special = make_symbol_special; +} + +CORE_ADDR +gdbarch_adjust_dwarf2_addr (struct gdbarch *gdbarch, CORE_ADDR pc) +{ + gdb_assert (gdbarch != NULL); + gdb_assert (gdbarch->adjust_dwarf2_addr != NULL); + if (gdbarch_debug >= 2) + fprintf_unfiltered (gdb_stdlog, "gdbarch_adjust_dwarf2_addr called\n"); + return gdbarch->adjust_dwarf2_addr (pc); +} + +void +set_gdbarch_adjust_dwarf2_addr (struct gdbarch *gdbarch, + gdbarch_adjust_dwarf2_addr_ftype adjust_dwarf2_addr) +{ + gdbarch->adjust_dwarf2_addr = adjust_dwarf2_addr; +} + +CORE_ADDR +gdbarch_adjust_dwarf2_line (struct gdbarch *gdbarch, CORE_ADDR addr, int rel) +{ + gdb_assert (gdbarch != NULL); + gdb_assert (gdbarch->adjust_dwarf2_line != NULL); + if (gdbarch_debug >= 2) + fprintf_unfiltered (gdb_stdlog, "gdbarch_adjust_dwarf2_line called\n"); + return gdbarch->adjust_dwarf2_line (addr, rel); +} + +void +set_gdbarch_adjust_dwarf2_line (struct gdbarch *gdbarch, + gdbarch_adjust_dwarf2_line_ftype adjust_dwarf2_line) +{ + gdbarch->adjust_dwarf2_line = adjust_dwarf2_line; +} + int gdbarch_cannot_step_breakpoint (struct gdbarch *gdbarch) { Index: gdb-fsf-trunk-quilt/gdb/gdbarch.h =================================================================== --- gdb-fsf-trunk-quilt.orig/gdb/gdbarch.h 2012-05-14 15:56:47.000000000 +0100 +++ gdb-fsf-trunk-quilt/gdb/gdbarch.h 2012-05-14 16:02:02.205560708 +0100 @@ -50,6 +50,8 @@ struct target_ops; struct obstack; struct bp_target_info; struct target_desc; +struct objfile; +struct symbol; struct displaced_step_closure; struct core_regset_section; struct syscall; @@ -658,6 +660,18 @@ typedef void (gdbarch_coff_make_msymbol_ extern void gdbarch_coff_make_msymbol_special (struct gdbarch *gdbarch, int val, struct minimal_symbol *msym); extern void set_gdbarch_coff_make_msymbol_special (struct gdbarch *gdbarch, gdbarch_coff_make_msymbol_special_ftype *coff_make_msymbol_special); +typedef void (gdbarch_make_symbol_special_ftype) (struct symbol *sym, struct objfile *objfile); +extern void gdbarch_make_symbol_special (struct gdbarch *gdbarch, struct symbol *sym, struct objfile *objfile); +extern void set_gdbarch_make_symbol_special (struct gdbarch *gdbarch, gdbarch_make_symbol_special_ftype *make_symbol_special); + +typedef CORE_ADDR (gdbarch_adjust_dwarf2_addr_ftype) (CORE_ADDR pc); +extern CORE_ADDR gdbarch_adjust_dwarf2_addr (struct gdbarch *gdbarch, CORE_ADDR pc); +extern void set_gdbarch_adjust_dwarf2_addr (struct gdbarch *gdbarch, gdbarch_adjust_dwarf2_addr_ftype *adjust_dwarf2_addr); + +typedef CORE_ADDR (gdbarch_adjust_dwarf2_line_ftype) (CORE_ADDR addr, int rel); +extern CORE_ADDR gdbarch_adjust_dwarf2_line (struct gdbarch *gdbarch, CORE_ADDR addr, int rel); +extern void set_gdbarch_adjust_dwarf2_line (struct gdbarch *gdbarch, gdbarch_adjust_dwarf2_line_ftype *adjust_dwarf2_line); + extern int gdbarch_cannot_step_breakpoint (struct gdbarch *gdbarch); extern void set_gdbarch_cannot_step_breakpoint (struct gdbarch *gdbarch, int cannot_step_breakpoint); Index: gdb-fsf-trunk-quilt/gdb/gdbarch.sh =================================================================== --- gdb-fsf-trunk-quilt.orig/gdb/gdbarch.sh 2012-05-14 15:56:47.000000000 +0100 +++ gdb-fsf-trunk-quilt/gdb/gdbarch.sh 2012-05-14 16:02:02.215560349 +0100 @@ -614,6 +614,9 @@ m:int:in_solib_return_trampoline:CORE_AD m:int:in_function_epilogue_p:CORE_ADDR addr:addr:0:generic_in_function_epilogue_p::0 f:void:elf_make_msymbol_special:asymbol *sym, struct minimal_symbol *msym:sym, msym::default_elf_make_msymbol_special::0 f:void:coff_make_msymbol_special:int val, struct minimal_symbol *msym:val, msym::default_coff_make_msymbol_special::0 +f:void:make_symbol_special:struct symbol *sym, struct objfile *objfile:sym, objfile::default_make_symbol_special::0 +f:CORE_ADDR:adjust_dwarf2_addr:CORE_ADDR pc:pc::default_adjust_dwarf2_addr::0 +f:CORE_ADDR:adjust_dwarf2_line:CORE_ADDR addr, int rel:addr, rel::default_adjust_dwarf2_line::0 v:int:cannot_step_breakpoint:::0:0::0 v:int:have_nonsteppable_watchpoint:::0:0::0 F:int:address_class_type_flags:int byte_size, int dwarf2_addr_class:byte_size, dwarf2_addr_class @@ -1044,6 +1047,8 @@ struct target_ops; struct obstack; struct bp_target_info; struct target_desc; +struct objfile; +struct symbol; struct displaced_step_closure; struct core_regset_section; struct syscall; Index: gdb-fsf-trunk-quilt/gdb/dwarf2-frame.c =================================================================== --- gdb-fsf-trunk-quilt.orig/gdb/dwarf2-frame.c 2012-05-14 15:56:43.000000000 +0100 +++ gdb-fsf-trunk-quilt/gdb/dwarf2-frame.c 2012-05-14 16:02:02.255559958 +0100 @@ -2095,6 +2095,7 @@ decode_frame_entry_1 (struct comp_unit * { /* This is a FDE. */ struct dwarf2_fde *fde; + CORE_ADDR addr; /* Check that an FDE was expected. */ if ((entry_type & EH_FDE_TYPE_ID) == 0) @@ -2128,14 +2129,16 @@ decode_frame_entry_1 (struct comp_unit * gdb_assert (fde->cie != NULL); - fde->initial_location = - read_encoded_value (unit, fde->cie->encoding, fde->cie->ptr_size, - buf, &bytes_read, 0); + addr = read_encoded_value (unit, fde->cie->encoding, fde->cie->ptr_size, + buf, &bytes_read, 0); + fde->initial_location = gdbarch_adjust_dwarf2_addr (gdbarch, addr); buf += bytes_read; fde->address_range = read_encoded_value (unit, fde->cie->encoding & 0x0f, fde->cie->ptr_size, buf, &bytes_read, 0); + addr = gdbarch_adjust_dwarf2_addr (gdbarch, addr + fde->address_range); + fde->address_range = addr - fde->initial_location; buf += bytes_read; /* A 'z' augmentation in the CIE implies the presence of an Index: gdb-fsf-trunk-quilt/gdb/dwarf2loc.c =================================================================== --- gdb-fsf-trunk-quilt.orig/gdb/dwarf2loc.c 2012-05-14 15:56:43.000000000 +0100 +++ gdb-fsf-trunk-quilt/gdb/dwarf2loc.c 2012-05-14 16:02:02.255559958 +0100 @@ -122,6 +122,9 @@ dwarf2_find_location_expression (struct low += base_address; high += base_address; + low = gdbarch_adjust_dwarf2_addr (gdbarch, low); + high = gdbarch_adjust_dwarf2_addr (gdbarch, high); + length = extract_unsigned_integer (loc_ptr, 2, byte_order); loc_ptr += 2; Index: gdb-fsf-trunk-quilt/gdb/solib.c =================================================================== --- gdb-fsf-trunk-quilt.orig/gdb/solib.c 2012-05-14 15:56:45.000000000 +0100 +++ gdb-fsf-trunk-quilt/gdb/solib.c 2012-05-14 16:01:34.645558637 +0100 @@ -1384,8 +1384,27 @@ gdb_bfd_lookup_symbol_from_symtab (bfd * if (match_sym (sym, data)) { + symaddr = sym->value; + + /* macro/2012-04-20: Some ELF targets fiddle with addresses + of symbols they consider special. They use minimal symbols + to do that and this is needed for correct breakpoint + placement, but we do not have full data here to build a + complete minimal symbol, so just set the address and let the + targets cope with that. */ + if (bfd_get_flavour (abfd) == bfd_target_elf_flavour) + { + struct minimal_symbol msym; + + memset (&msym, 0, sizeof (msym)); + SYMBOL_VALUE_ADDRESS (&msym) = symaddr; + gdbarch_elf_make_msymbol_special (target_gdbarch, + sym, &msym); + symaddr = SYMBOL_VALUE_ADDRESS (&msym); + } + /* BFD symbols are section relative. */ - symaddr = sym->value + sym->section->vma; + symaddr += sym->section->vma; break; } }