* Patch to allow ARM dynamic linker to fix up PC24 relocs...
@ 1999-12-21 8:19 Scott Bambrough
1999-12-21 8:29 ` Ulrich Drepper
0 siblings, 1 reply; 9+ messages in thread
From: Scott Bambrough @ 1999-12-21 8:19 UTC (permalink / raw)
To: libc-hacker mailing list
The attached patch adds a cache flush just after the readonly protection
is restored to .text. I've done this in generic code, because the cache
flush is an extremely expensive operation on the ARM. We don't want to
do this after every fixup, and only if we do fixups. The patch as
written should only affect the ARM (or anyone else who defines
CLEAR_CACHE). For all other targets it will disappear after
pre-processing. This patch has the fix for the problem Phil Blundell
pointed out. I've tested it and it seems to work.
1999-12-21 Scott Bambrough <scottb@netwinder.org>
* sysdeps/arm/dl-machine.h (CLEAR_CACHE): New macro to force a
cache flush.
* elf/dl-reloc.c (_dl_relocate_object): Add call to flush cache
after .text segment fixups.
Scott
--
Scott Bambrough - Software Engineer
REBEL.COM http://www.rebel.com
NetWinder http://www.netwinder.org
diff -upr glibc-2.1.2.orig/elf/dl-reloc.c glibc-2.1.2/elf/dl-reloc.c
--- glibc-2.1.2.orig/elf/dl-reloc.c Sat Feb 20 09:45:53 1999
+++ glibc-2.1.2/elf/dl-reloc.c Fri Dec 10 10:36:33 1999
@@ -126,6 +126,10 @@ _dl_relocate_object (struct link_map *l,
if (__mprotect (mapstart, mapend - mapstart, prot) < 0)
_dl_signal_error (errno, l->l_name,
"can't restore segment prot after reloc");
+
+#ifdef CLEAR_CACHE
+ CLEAR_CACHE (mapstart, mapend);
+#endif
}
}
}
diff -upr glibc-2.1.2.orig/sysdeps/arm/dl-machine.h glibc-2.1.2/sysdeps/arm/dl-machine.h
--- glibc-2.1.2.orig/sysdeps/arm/dl-machine.h Tue Aug 10 01:13:22 1999
+++ glibc-2.1.2/sysdeps/arm/dl-machine.h Fri Dec 10 10:36:57 1999
@@ -35,6 +35,14 @@
VALID_ELF_ABIVERSION(hdr[EI_ABIVERSION]) \
)
+#define CLEAR_CACHE(BEG,END) \
+{ \
+ register unsigned long _beg __asm ("a1") = (unsigned long)(BEG); \
+ register unsigned long _end __asm ("a2") = (unsigned long)(END); \
+ register unsigned long _flg __asm ("a3") = 0; \
+ __asm __volatile ("swi 0x9f0002"); \
+}
+
/* Return nonzero iff E_MACHINE is compatible with the running host. */
static inline int __attribute__ ((unused))
elf_machine_matches_host (Elf32_Half e_machine)
^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: Patch to allow ARM dynamic linker to fix up PC24 relocs...
1999-12-21 8:19 Patch to allow ARM dynamic linker to fix up PC24 relocs Scott Bambrough
@ 1999-12-21 8:29 ` Ulrich Drepper
1999-12-21 8:37 ` Scott Bambrough
0 siblings, 1 reply; 9+ messages in thread
From: Ulrich Drepper @ 1999-12-21 8:29 UTC (permalink / raw)
To: Scott Bambrough; +Cc: libc-hacker mailing list
Scott Bambrough <scottb@netwinder.org> writes:
> The attached patch adds a cache flush just after the readonly protection
> is restored to .text. I've done this in generic code, because the cache
> flush is an extremely expensive operation on the ARM. We don't want to
> do this after every fixup, and only if we do fixups. The patch as
> written should only affect the ARM (or anyone else who defines
> CLEAR_CACHE). For all other targets it will disappear after
> pre-processing. This patch has the fix for the problem Phil Blundell
> pointed out. I've tested it and it seems to work.
I've already added this code to 2.1.3. Could you update your tree?
--
---------------. drepper at gnu.org ,-. 1325 Chesapeake Terrace
Ulrich Drepper \ ,-------------------' \ Sunnyvale, CA 94089 USA
Cygnus Solutions `--' drepper at cygnus.com `------------------------
^ permalink raw reply [flat|nested] 9+ messages in thread
* Patch to allow ARM dynamic linker to fix up PC24 relocs...
@ 1999-12-07 11:50 Scott Bambrough
1999-12-07 12:12 ` Philip Blundell
1999-12-07 23:38 ` Ulrich Drepper
0 siblings, 2 replies; 9+ messages in thread
From: Scott Bambrough @ 1999-12-07 11:50 UTC (permalink / raw)
To: libc-hacker mailing list
Hi guys,
The attached patch allows the ARM dynamic linker to fix up PC24 relocs
in the code segment. A bit of background is attached.
The PC24 reloc is generated for ARM branch and branch and link
instructions (b,bl). The least significant 24 bits are used to for a 26
bit offset (the offset is modulo 4). The address calculation performed
by the CPU is as follows:
PC = PC + (SignExtend(<24_bit_signed_offset>) << 2;
If the calculated 26 bit offset is out of range, the dynamic linker
displays an error message like the following:
foo_dynamic: error in loading shared libraries: ./foo.so: R_ARM_PC24
relocation out of range
1999-12-07 Scott Bambrough <scottb@netwinder.org>
* sysdeps/arm/dl-machine.h (elf_machine_rel): Fixup R_ARM_PC24
relocs if possible.
--
Scott Bambrough - Software Engineer
REBEL.COM http://www.rebel.com
NetWinder http://www.netwinder.org
--- dl-machine.h.orig Fri Nov 26 08:56:05 1999
+++ dl-machine.h Tue Dec 7 14:04:13 1999
@@ -446,6 +446,23 @@ elf_machine_rel (struct link_map *map, c
*reloc_addr += value;
break;
}
+ case R_ARM_PC24:
+ {
+ signed int addend;
+
+ addend = *reloc_addr & 0x00ffffff;
+ if (addend & 0x00800000) addend |= 0xff000000;
+
+ value = value - (unsigned int)reloc_addr + (addend << 2);
+ if (value & 0xfc000003)
+ _dl_signal_error (0, map->l_name,
+ "R_ARM_PC24 relocation out of range");
+
+ value = value >> 2;
+ value = (*reloc_addr & 0xff000000) | (value & 0x00ffffff);
+ *reloc_addr = value;
+ }
+ break;
default:
assert (! "unexpected dynamic reloc type");
break;
^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: Patch to allow ARM dynamic linker to fix up PC24 relocs...
1999-12-07 11:50 Scott Bambrough
@ 1999-12-07 12:12 ` Philip Blundell
1999-12-07 18:37 ` Richard Henderson
1999-12-07 23:38 ` Ulrich Drepper
1 sibling, 1 reply; 9+ messages in thread
From: Philip Blundell @ 1999-12-07 12:12 UTC (permalink / raw)
To: Scott Bambrough; +Cc: libc-hacker mailing list
> * sysdeps/arm/dl-machine.h (elf_machine_rel): Fixup R_ARM_PC24
> relocs if possible.
This is fine as far as it goes, but you probably want to add code to
synchronise the StrongARM caches if we are going to get into modifying the
text segment.
p.
^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: Patch to allow ARM dynamic linker to fix up PC24 relocs...
1999-12-07 12:12 ` Philip Blundell
@ 1999-12-07 18:37 ` Richard Henderson
[not found] ` <E11veej-0007M5-00@>
0 siblings, 1 reply; 9+ messages in thread
From: Richard Henderson @ 1999-12-07 18:37 UTC (permalink / raw)
To: Philip Blundell; +Cc: Scott Bambrough, libc-hacker mailing list
On Tue, Dec 07, 1999 at 08:12:20PM +0000, Philip Blundell wrote:
> This is fine as far as it goes, but you probably want to add code to
> synchronise the StrongARM caches if we are going to get into modifying the
> text segment.
This will only happen during program startup. The code in
question is not in the Icache yet.
r~
^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: Patch to allow ARM dynamic linker to fix up PC24 relocs...
1999-12-07 11:50 Scott Bambrough
1999-12-07 12:12 ` Philip Blundell
@ 1999-12-07 23:38 ` Ulrich Drepper
1 sibling, 0 replies; 9+ messages in thread
From: Ulrich Drepper @ 1999-12-07 23:38 UTC (permalink / raw)
To: Scott Bambrough; +Cc: libc-hacker mailing list
Scott Bambrough <scottb@netwinder.org> writes:
> The attached patch allows the ARM dynamic linker to fix up PC24 relocs
> in the code segment.
Thanks, I've applied it.
--
---------------. drepper at gnu.org ,-. 1325 Chesapeake Terrace
Ulrich Drepper \ ,-------------------' \ Sunnyvale, CA 94089 USA
Cygnus Solutions `--' drepper at cygnus.com `------------------------
^ permalink raw reply [flat|nested] 9+ messages in thread
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1999-12-21 8:19 Patch to allow ARM dynamic linker to fix up PC24 relocs Scott Bambrough
1999-12-21 8:29 ` Ulrich Drepper
1999-12-21 8:37 ` Scott Bambrough
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1999-12-07 11:50 Scott Bambrough
1999-12-07 12:12 ` Philip Blundell
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1999-12-17 8:53 ` Scott Bambrough
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1999-12-17 9:40 ` Scott Bambrough
1999-12-07 23:38 ` Ulrich Drepper
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