[Bug tree-optimization/44290] New: arm linux kernel crahes when built with -fipa-sra

[Bug tree-optimization/44290] New: arm linux kernel crahes when built with -fipa-sra

[raj dot khem at gmail dot com]

While trying to boot linux 2.6.34 built with gcc from latest gcc-4_5-branch the
kernel would not boot. Same kernel would work fine with gcc 4.4.4 Reducing to
individual optimization phases. So far I have seen that when compiled with -O2
the kernel crashes however when I change the flags to -O2 -fno-ipa-sra then
it works well. 

I don't have a small test-case as of now. I am trying to reduce it but it might
take some time. Meanwhile I wanted to open the bug so that if someone else
has information on similar issue can chime in.


-- 
           Summary: arm linux kernel crahes when built with -fipa-sra
           Product: gcc
           Version: 4.5.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: raj dot khem at gmail dot com
 GCC build triplet: x86_64-linux
  GCC host triplet: x86_64-linux
GCC target triplet: arm-none-linux-uclibcgnueabi


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44290

[Bug tree-optimization/44290] arm linux kernel crahes when built with -fipa-sra

[raj dot khem at gmail dot com]

------- Comment #1 from raj dot khem at gmail dot com  2010-05-27 07:06 -------
Created an attachment (id=20759)
 --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=20759&action=view)
preprocessed testcase

OK so here is one file which whic is compiled with -O2 -fno-ipa-sra and rest of
kernel with -O2  and it works ok. So something is going wrong in this file.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44290

[Bug tree-optimization/44290] arm linux kernel crahes when built with -fipa-sra

[raj dot khem at gmail dot com]

------- Comment #2 from raj dot khem at gmail dot com  2010-05-27 07:12 -------
here is diff of two assembly outputs

$ diff copypage-v4wb.s copypage-v4wb.no-ipa-sra.S -u
--- copypage-v4wb.s     2010-05-27 00:11:03.130607878 -0700
+++ copypage-v4wb.no-ipa-sra.S  2010-05-27 00:10:54.790615578 -0700
@@ -120,19 +120,30 @@
 v4wb_copy_user_highpage:
        @ args = 0, pretend = 0, frame = 0
        @ frame_needed = 0, uses_anonymous_args = 0
-       stmfd   sp!, {r4, lr}
-       mov     r1, sp
-       bic     r4, r1, #8128
+       stmfd   sp!, {r4, r5, r6, lr}
+       mov     ip, sp
+       bic     r4, ip, #8128
        bic     r4, r4, #63
-       ldr     r1, [r4, #4]
-       add     r1, r1, #1
-       str     r1, [r4, #4]
-       ldr     r1, [r4, #4]
-       add     r1, r1, #1
-       str     r1, [r4, #4]
-       ldr     r1, [r3, #0]
-       ldr     r1, [r1, #332]
-       tst     r1, #1
+       ldr     ip, [r4, #4]
+       add     ip, ip, #1
+       str     ip, [r4, #4]
+       ldr     ip, .L8
+       ldr     lr, [r4, #4]
+       ldr     r6, [ip, #0]
+       add     lr, lr, #1
+       rsb     r6, r6, r0
+       mov     r6, r6, asr #5
+       mov     r6, r6, asl #12
+       add     r6, r6, #-1073741824
+       str     lr, [r4, #4]
+       ldr     r5, [ip, #0]
+       ldr     r0, [r3, #0]
+       rsb     r5, r5, r1
+       ldr     r0, [r0, #332]
+       mov     r5, r5, asr #5
+       mov     r5, r5, asl #12
+       tst     r0, #1
+       add     r5, r5, #-1073741824
        beq     .L6
        bic     r2, r2, #4080
        bic     r0, r2, #15
@@ -140,6 +151,8 @@
        ldr     r2, [r3, #20]
        bl      arm926_flush_user_cache_range
 .L6:
+       mov     r0, r6
+       mov     r1, r5
        bl      v4wb_copy_user_page
        ldr     r3, [r4, #4]
        sub     r3, r3, #1
@@ -147,7 +160,11 @@
        ldr     r3, [r4, #4]
        sub     r3, r3, #1
        str     r3, [r4, #4]
-       ldmfd   sp!, {r4, pc}
+       ldmfd   sp!, {r4, r5, r6, pc}
+.L9:
+       .align  2
+.L8:
+       .word   mem_map
        .size   v4wb_copy_user_highpage, .-v4wb_copy_user_highpage
        .global v4wb_user_fns
        .section        .init.data,"aw",%progbits


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44290

[Bug tree-optimization/44290] [4.5 Regression] arm linux kernel crahes when built with -fipa-sra

[rguenth at gcc dot gnu dot org]

------- Comment #3 from rguenth at gcc dot gnu dot org  2010-05-27 10:40 -------
Can you paste the output of gcc when adding -v to the commandline used for
compiling copypage-v4wb.i in the failing case?


-- 

rguenth at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |jamborm at gcc dot gnu dot
                   |                            |org
            Summary|arm linux kernel crahes when|[4.5 Regression] arm linux
                   |built with -fipa-sra        |kernel crahes when built
                   |                            |with -fipa-sra
   Target Milestone|---                         |4.5.1


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44290

[Bug tree-optimization/44290] [4.5 Regression] arm linux kernel crahes when built with -fipa-sra

[raj dot khem at gmail dot com]

------- Comment #4 from raj dot khem at gmail dot com  2010-05-27 17:25 -------
$
/home/kraj/work/cross/arm-none-linux-uclibcgnueabi/tools/bin/arm-none-linux-uclibcgnueabi-gcc
-O2 -fno-ipa-sra -S -v copypage-v4wb.i
Using built-in specs.
COLLECT_GCC=/home/kraj/work/cross/arm-none-linux-uclibcgnueabi/tools/bin/arm-none-linux-uclibcgnueabi-gcc
COLLECT_LTO_WRAPPER=/home/kraj/work/cross/arm-none-linux-uclibcgnueabi/tools/libexec/gcc/arm-none-linux-uclibcgnueabi/4.5.1/lto-wrapper
Target: arm-none-linux-uclibcgnueabi
Configured with:
/home/kraj/work/cross/arm-none-linux-uclibcgnueabi/../../gcc-4.5-20100520/configure
--target=arm-none-linux-uclibcgnueabi
--prefix=/home/kraj/work/cross/arm-none-linux-uclibcgnueabi/tools
--with-sysroot=/home/kraj/work/cross/arm-none-linux-uclibcgnueabi/sysroot
--enable-__cxa_atexit --disable-libssp --disable-libgomp --disable-libmudflap
--enable-languages=c,c++
Thread model: posix
gcc version 4.5.1 20100520 (prerelease) (GCC) 
COLLECT_GCC_OPTIONS='-O2' '-fno-ipa-sra' '-S' '-v'

/home/kraj/work/cross/arm-none-linux-uclibcgnueabi/tools/libexec/gcc/arm-none-linux-uclibcgnueabi/4.5.1/cc1
-fpreprocessed copypage-v4wb.i -quiet -dumpbase copypage-v4wb.i -auxbase
copypage-v4wb -O2 -version -fno-ipa-sra -o copypage-v4wb.s
GNU C (GCC) version 4.5.1 20100520 (prerelease) (arm-none-linux-uclibcgnueabi)
        compiled by GNU C version 4.4.3, GMP version 4.3.2, MPFR version
2.4.2-p1, MPC version 0.8.1
GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
GNU C (GCC) version 4.5.1 20100520 (prerelease) (arm-none-linux-uclibcgnueabi)
        compiled by GNU C version 4.4.3, GMP version 4.3.2, MPFR version
2.4.2-p1, MPC version 0.8.1
GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
Compiler executable checksum: acf86197000a593407366115824f5d00
COMPILER_PATH=/home/kraj/work/cross/arm-none-linux-uclibcgnueabi/tools/libexec/gcc/arm-none-linux-uclibcgnueabi/4.5.1/:/home/kraj/work/cross/arm-none-linux-uclibcgnueabi/tools/libexec/gcc/arm-none-linux-uclibcgnueabi/4.5.1/:/home/kraj/work/cross/arm-none-linux-uclibcgnueabi/tools/libexec/gcc/arm-none-linux-uclibcgnueabi/:/home/kraj/work/cross/arm-none-linux-uclibcgnueabi/tools/lib/gcc/arm-none-linux-uclibcgnueabi/4.5.1/:/home/kraj/work/cross/arm-none-linux-uclibcgnueabi/tools/lib/gcc/arm-none-linux-uclibcgnueabi/:/home/kraj/work/cross/arm-none-linux-uclibcgnueabi/tools/lib/gcc/arm-none-linux-uclibcgnueabi/4.5.1/../../../../arm-none-linux-uclibcgnueabi/bin/
LIBRARY_PATH=/home/kraj/work/cross/arm-none-linux-uclibcgnueabi/tools/lib/gcc/arm-none-linux-uclibcgnueabi/4.5.1/:/home/kraj/work/cross/arm-none-linux-uclibcgnueabi/tools/lib/gcc/arm-none-linux-uclibcgnueabi/4.5.1/../../../../arm-none-linux-uclibcgnueabi/lib/:/home/kraj/work/cross/arm-none-linux-uclibcgnueabi/sysroot/lib/:/home/kraj/work/cross/arm-none-linux-uclibcgnueabi/sysroot/usr/lib/
COLLECT_GCC_OPTIONS='-O2' '-fno-ipa-sra' '-S' '-v'


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44290

[Bug tree-optimization/44290] [4.5 Regression] arm linux kernel crahes when built with -fipa-sra

[raj dot khem at gmail dot com]

------- Comment #5 from raj dot khem at gmail dot com  2010-05-27 17:27 -------
oops that was for good case. But just remove -fno-ipa-sra to make it a failing
case :)


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44290

[Bug tree-optimization/44290] [4.5 Regression] arm linux kernel crahes when built with -fipa-sra

[mikpe at it dot uu dot se]

------- Comment #6 from mikpe at it dot uu dot se  2010-05-28 11:49 -------
Confirmed.  A linux-2.6.34 kernel configured for ARM and compiled with
gcc-4.5-20100520 crashes during boot with a NULL pointer dereference in its
copy_user_highpage() exactly at the point where it tries to start /sbin/init.  
HIGHMEM enabled or not makes no difference.  The same kernel compiled with
gcc-4.4.4 boots fine.

Both gcc's were configured for armv5tel-unknown-linux-gnu --with-arch=armv5te
--with-tune=xscale.  The linux kernels were built for mach-iop32x/n2100 (XScale
IOP80219).

I note that copypage-xscale.c:xscale_mc_copy_user_highpage() calls a __naked
function to do the bulk copy.  Converting that to a plain inline function
(changing 'pc' to 'lr' in the final instruction that restores the scrach regs),
does not prevent the crash.  So I suspect a plain C code miscompilation.

I'll try to bisect it.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44290

[Bug tree-optimization/44290] [4.5 Regression] arm linux kernel crahes when built with -fipa-sra

[mikpe at it dot uu dot se]

------- Comment #7 from mikpe at it dot uu dot se  2010-05-28 22:02 -------
Bisection identified r148981 as the cause of this regression:

Author: rth
Date: Fri Jun 26 18:23:32 2009
New Revision: 148981

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=148981
Log:
        * function.h (struct function): Add cannot_be_copied_reason,
        and cannot_be_copied_set.
        * tree-inline.c (has_label_address_in_static_1): Rename from
        inline_forbidden_p_2; don't set inline_forbidden_reason here.
        (cannot_copy_type_1): Rename from inline_forbidden_p_op; likewise
        don't set inline_forbidden_reason.
        (copy_forbidden): New function, split out of inline_forbidden_p.
        (inline_forbidden_p_stmt): Don't check for nonlocal labels here.
        (inline_forbidden_p): Use copy_forbidden.
        (tree_versionable_function_p): Likewise.
        (inlinable_function_p): Merge into tree_inlinable_function_p.
        (tree_function_versioning): Remap cfun->nonlocal_goto_save_area.
        * ipa-cp.c (ipcp_versionable_function_p): New function.
        (ipcp_cloning_candidate_p): Use it.
        (ipcp_node_modifiable_p): Likewise.

I'll try to extract a smaller test case tomorrow.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44290

[Bug tree-optimization/44290] [4.5 Regression] arm linux kernel crahes when built with -fipa-sra

[mikpe at it dot uu dot se]

------- Comment #8 from mikpe at it dot uu dot se  2010-05-29 11:35 -------
(In reply to comment #6)
> I note that copypage-xscale.c:xscale_mc_copy_user_highpage() calls a __naked
> function to do the bulk copy.  Converting that to a plain inline function
> (changing 'pc' to 'lr' in the final instruction that restores the scrach regs),
> does not prevent the crash.  So I suspect a plain C code miscompilation.

Actually that conversion away from __naked may have been flawed.  What I'm
seeing is that r148981 causes gcc to clone the __naked function and change its
calling conventions in ways that don't match the proper function call ABI. 
This breaks the body of the __naked function which is just a big asm()
statement.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44290

[Bug target/44290] [4.5 Regression] arm linux kernel crahes when built with -fipa-sra, __naked attribute is broken

[rguenth at gcc dot gnu dot org]

------- Comment #9 from rguenth at gcc dot gnu dot org  2010-05-29 11:42 -------
(In reply to comment #8)
> (In reply to comment #6)
> > I note that copypage-xscale.c:xscale_mc_copy_user_highpage() calls a __naked
> > function to do the bulk copy.  Converting that to a plain inline function
> > (changing 'pc' to 'lr' in the final instruction that restores the scrach regs),
> > does not prevent the crash.  So I suspect a plain C code miscompilation.
> 
> Actually that conversion away from __naked may have been flawed.  What I'm
> seeing is that r148981 causes gcc to clone the __naked function and change its
> calling conventions in ways that don't match the proper function call ABI. 
> This breaks the body of the __naked function which is just a big asm()
> statement.

Well.  The arm backend needs to mark the function as "used in non-visible
ways" then.  Thus this is a target bug.


-- 

rguenth at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
          Component|tree-optimization           |target
     Ever Confirmed|0                           |1
   Last reconfirmed|0000-00-00 00:00:00         |2010-05-29 11:42:59
               date|                            |
            Summary|[4.5 Regression] arm linux  |[4.5 Regression] arm linux
                   |kernel crahes when built    |kernel crahes when built
                   |with -fipa-sra              |with -fipa-sra, __naked
                   |                            |attribute is broken


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44290

[Bug target/44290] [4.5 Regression] arm linux kernel crahes when built with -fipa-sra, __naked attribute is broken

[rguenth at gcc dot gnu dot org]

------- Comment #10 from rguenth at gcc dot gnu dot org  2010-05-29 11:47 -------
Or rather, if you have

void __attribute__((naked)) foo (int i)
{
  asm("use i");
}

without any inputs refering to i that is invalid.  Like I see in the
attached preprocessed source:

static void __attribute__((naked)) __attribute__((no_instrument_function))
v4wb_copy_user_page(void *kto, const void *kfrom)
{
 asm("  stmfd   sp!, {r4, lr}                   @ 2\n   mov     r2, %0         
                @ 1\n   ldmia   r1!, {r3, r4, ip, lr}           @ 4\n1: mcr    
p15, 0, r0, c7, c6, 1           @ 1   invalidate D line\n       stmia   r0!,
{r3, r4, ip, lr}           @ 4\n   ldmia   r1!, {r3, r4, ip, lr}           @
4+1\n stmia   r0!, {r3, r4, ip, lr}           @ 4\n   ldmia   r1!, {r3, r4, ip,
lr}           @ 4\n   mcr     p15, 0, r0, c7, c6, 1           @ 1   invalidate
D line\n       stmia   r0!, {r3, r4, ip, lr}           @ 4\n   ldmia   r1!,
{r3, r4, ip, lr}           @ 4\n   subs    r2, r2, #1                      @
1\n   stmia   r0!, {r3, r4, ip, lr}           @ 4\n   ldmneia r1!, {r3, r4, ip,
lr}           @ 4\n   bne     1b                              @ 1\n   mcr    
p15, 0, r1, c7, c10, 4          @ 1   drain WB\n        ldmfd    sp!, {r4, pc} 
                @ 3"
# 46 "/home/kraj/work/linux-2.6.34/arch/arm/mm/copypage-v4wb.c"
 :
 : "I" (((1UL) << 12) / 64));
}

kto and kfrom are unused.


-- 

rguenth at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|                            |INVALID


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44290

[Bug target/44290] [4.5 Regression] arm linux kernel crahes when built with -fipa-sra, __naked attribute is broken

[rguenth at gcc dot gnu dot org]

------- Comment #11 from rguenth at gcc dot gnu dot org  2010-05-29 11:50 -------
(it seems quite stupid to have naked functions with only an asm inside in the
first place - you can equally well use plain assembly)


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44290

Re: [Bug target/44290] [4.5 Regression] arm linux kernel crahes when built with -fipa-sra, __naked attribute is broken

[Andrew Pinski]

The naked attribute should cause two things noinline and noclone.

Sent from my iPhone

On May 29, 2010, at 4:50 AM, "rguenth at gcc dot gnu dot org" <gcc-bugzilla@gcc.gnu.org 
 > wrote:

>
>
> ------- Comment #11 from rguenth at gcc dot gnu dot org  2010-05-29  
> 11:50 -------
> (it seems quite stupid to have naked functions with only an asm  
> inside in the
> first place - you can equally well use plain assembly)
>
>
> -- 
>
>
> http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44290
>

[Bug target/44290] [4.5 Regression] arm linux kernel crahes when built with -fipa-sra, __naked attribute is broken

[pinskia at gmail dot com]

------- Comment #12 from pinskia at gmail dot com  2010-05-29 13:30 -------
Subject: Re:  [4.5 Regression] arm linux kernel crahes when built with
-fipa-sra, __naked attribute is broken

The naked attribute should cause two things noinline and noclone.

Sent from my iPhone

On May 29, 2010, at 4:50 AM, "rguenth at gcc dot gnu dot org"
<gcc-bugzilla@gcc.gnu.org 
 > wrote:

>
>
> ------- Comment #11 from rguenth at gcc dot gnu dot org  2010-05-29  
> 11:50 -------
> (it seems quite stupid to have naked functions with only an asm  
> inside in the
> first place - you can equally well use plain assembly)
>
>
> -- 
>
>
> http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44290
>


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44290

[Bug target/44290] [4.5 Regression] arm linux kernel crahes when built with -fipa-sra, __naked attribute is broken

[mikpe at it dot uu dot se]

------- Comment #13 from mikpe at it dot uu dot se  2010-05-29 14:27 -------
(In reply to comment #10)
> Or rather, if you have
> 
> void __attribute__((naked)) foo (int i)
> {
>   asm("use i");
> }
> 
> without any inputs refering to i that is invalid.

Not according to gcc/doc/extend.texi:

> @item naked
> @cindex function without a prologue/epilogue code
> Use this attribute on the ARM, AVR, IP2K, RX and SPU ports to indicate that
> the specified function does not need prologue/epilogue sequences generated by
> the compiler.  It is up to the programmer to provide these sequences. The 
> only statements that can be safely included in naked functions are 
> @code{asm} statements that do not have operands.

Note: "do not have operands".  Thus the only way such an asm() can refer to
parameters is by assuming a standard function call sequence and hardcoding
corresponding register numbers or stack frame offsets.

However, even if the asm() refers to those parameters via "r"(...) inputs,
gcc-4.5 changes the register assignment to not agree with the standard call
sequence, I'll attach a small test case showing that in a moment.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44290

[Bug target/44290] [4.5 Regression] arm linux kernel crahes when built with -fipa-sra, __naked attribute is broken

[mikpe at it dot uu dot se]

------- Comment #14 from mikpe at it dot uu dot se  2010-05-29 14:39 -------
(In reply to comment #11)
> (it seems quite stupid to have naked functions with only an asm inside in the
> first place - you can equally well use plain assembly)

Except that with plain asm() for an entire function definition you'd also have
to include boring preamble/postamble stuff like .align/.type/.size if you want
it to appear as a proper function, and you still have to declarate a prototype.

And the reason for making it a separate function rather than an inline asm() is
probably related to register assignment: a separate function can (could) make
assumptions about parameter registers and scratch registers.  With inline asm()
you have to be much more elaborate, esp. if you have constraints that gcc
cannot express, like even/odd register pairs on ARM.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44290

[Bug target/44290] [4.5 Regression] __naked attribute is broken

[rguenth at gcc dot gnu dot org]

------- Comment #15 from rguenth at gcc dot gnu dot org  2010-05-29 14:45 -------
(In reply to comment #13)
> (In reply to comment #10)
> > Or rather, if you have
> > 
> > void __attribute__((naked)) foo (int i)
> > {
> >   asm("use i");
> > }
> > 
> > without any inputs refering to i that is invalid.
> 
> Not according to gcc/doc/extend.texi:
> 
> > @item naked
> > @cindex function without a prologue/epilogue code
> > Use this attribute on the ARM, AVR, IP2K, RX and SPU ports to indicate that
> > the specified function does not need prologue/epilogue sequences generated by
> > the compiler.  It is up to the programmer to provide these sequences. The 
> > only statements that can be safely included in naked functions are 
> > @code{asm} statements that do not have operands.
> 
> Note: "do not have operands".  Thus the only way such an asm() can refer to
> parameters is by assuming a standard function call sequence and hardcoding
> corresponding register numbers or stack frame offsets.

Then the target has to properly communicate this to the middle-end.

> However, even if the asm() refers to those parameters via "r"(...) inputs,
> gcc-4.5 changes the register assignment to not agree with the standard call
> sequence, I'll attach a small test case showing that in a moment.

I'd have required dummy inputs like "g" (kto), "g" (kfrom) not used by
the actual assembly.

For now re-open as a target bug.


-- 

rguenth at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|RESOLVED                    |REOPENED
         Resolution|INVALID                     |
            Summary|[4.5 Regression] arm linux  |[4.5 Regression] __naked
                   |kernel crahes when built    |attribute is broken
                   |with -fipa-sra, __naked     |
                   |attribute is broken         |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44290

[Bug target/44290] [4.5 Regression] __naked attribute is broken

[rguenth at gcc dot gnu dot org]

------- Comment #16 from rguenth at gcc dot gnu dot org  2010-05-29 14:46 -------
And CC a arm maintainer.  There might be more target-specific attributes that
need adjustment.


-- 

rguenth at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |rearnsha at gcc dot gnu dot
                   |                            |org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44290

[Bug target/44290] [4.5 Regression] __naked attribute is broken

[mikpe at it dot uu dot se]

------- Comment #17 from mikpe at it dot uu dot se  2010-05-29 14:47 -------
Created an attachment (id=20772)
 --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=20772&action=view)
test case from copypage-xscale.c

This is distilled from the kernel's copypage-xscale.c file and illustrates the
issue.  With gcc-4.4 the __naked__ function foo() is called with the standard
call sequence register assignment, so the asm() body of foo() works.  With
gcc-4.5 foo() is cloned and gets its second parameter `to' in r0 (not r1 as
expected), and the body of foo() is modified to set up the actual first
parameter (&fie[0]) in r1 (not r0 as expected).  Obviously the asm() then
breaks.

Compiling with -fno-ipa-cp avoids this problem, as does adding __noclone__ and
__noinline__ to foo()'s function definition.

I don't immediately see how to enforce __noclone__ and __noinline__ in the ARM
backend when it sees __naked__.  Any ideas?


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44290

[Bug target/44290] [4.5 Regression] __naked attribute is broken

[mikpe at it dot uu dot se]

------- Comment #18 from mikpe at it dot uu dot se  2010-05-29 18:00 -------
Created an attachment (id=20773)
 --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=20773&action=view)
linux kernel workaround for attribute naked breakage

This patch makes the Linux kernel add noinline and noclone attributes to
functions declared __naked.  This allows gcc-4.5 to build a working 2.6.34
Linux kernel for my mach-iop32x/n2100 ARM box.

Khem: can you check if this kernel-side workaround fixes your problem?

Eventually I'd like the kernel to not use __naked, but that is non-trivial. 
This fix should work now and be easily backportable to older kernels.


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44290

[Bug target/44290] [4.5 Regression] __naked attribute is broken

[raj dot khem at gmail dot com]

------- Comment #19 from raj dot khem at gmail dot com  2010-05-30 05:58 -------
(In reply to comment #18)
> Created an attachment (id=20773)
 --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=20773&action=view) [edit]
> linux kernel workaround for attribute naked breakage
> 
> This patch makes the Linux kernel add noinline and noclone attributes to
> functions declared __naked.  This allows gcc-4.5 to build a working 2.6.34
> Linux kernel for my mach-iop32x/n2100 ARM box.
> 
> Khem: can you check if this kernel-side workaround fixes your problem?

I have tried using __noclone__ a couple of days ago to workaround the problem
//static void __attribute__((__naked__, __noinline__, __noclone__,
__no_instrument_function__))

static void __attribute__((__naked__, __no_instrument_function__))
v4wb_copy_user_page(void *kto, const void *kfrom)

But my gcc seems to ignore it and its generating same code for both with Os and
O2 for both
above cases. Hence did not solve my issue.
I am using snapshot of 4.5 branch from May 20

> 
> Eventually I'd like the kernel to not use __naked, but that is non-trivial. 
> This fix should work now and be easily backportable to older kernels.
> 


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44290

[Bug target/44290] [4.5 Regression] __naked attribute is broken

[raj dot khem at gmail dot com]

------- Comment #20 from raj dot khem at gmail dot com  2010-05-30 06:54 -------
Created an attachment (id=20777)
 --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=20777&action=view)
includes fix for all arms

I see the problem after reading Richard's comment #10, here is some more
additions to kernel workaround patch which work for me too.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44290

[Bug target/44290] [4.5 Regression] __naked attribute is broken

[rguenth at gcc dot gnu dot org]

-- 

rguenth at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Priority|P3                          |P2


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44290

[Bug target/44290] [4.5 Regression] __naked attribute is broken

[jiez at gcc dot gnu dot org]

------- Comment #21 from jiez at gcc dot gnu dot org  2010-07-23 14:48 -------
Subject: Bug 44290

Author: jiez
Date: Fri Jul 23 14:47:46 2010
New Revision: 162466

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=162466
Log:
        PR target/44290
        * attribs.c (decl_attributes): Insert "noinline" and "noclone"
        if "naked".
        * tree-sra.c (ipa_sra_preliminary_function_checks): Return
        false if ! tree_versionable_function_p.

        testsuite/
        PR target/44290
        * gcc.dg/pr44290-1.c: New test.
        * gcc.dg/pr44290-2.c: New test.

Added:
    trunk/gcc/testsuite/gcc.dg/pr44290-1.c
    trunk/gcc/testsuite/gcc.dg/pr44290-2.c
Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/attribs.c
    trunk/gcc/testsuite/ChangeLog
    trunk/gcc/tree-sra.c


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44290

[Bug target/44290] [4.5 Regression] __naked attribute is broken

[jiez at gcc dot gnu dot org]

------- Comment #22 from jiez at gcc dot gnu dot org  2010-07-23 14:51 -------
Should be fixed on trunk now.


-- 

jiez at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         AssignedTo|unassigned at gcc dot gnu   |jiez at gcc dot gnu dot org
                   |dot org                     |
             Status|REOPENED                    |ASSIGNED


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44290

[Bug target/44290] [4.5 Regression] __naked attribute is broken

[jiez at gcc dot gnu dot org]

------- Comment #23 from jiez at gcc dot gnu dot org  2010-07-23 14:52 -------
Set the status to FIXED.


-- 

jiez at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |RESOLVED
         Resolution|                            |FIXED


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44290

[Bug target/44290] [4.5 only] __naked attribute is broken

[ramana at gcc dot gnu dot org]

------- Comment #24 from ramana at gcc dot gnu dot org  2010-07-26 08:05 -------
If this is fixed, the target milestone should be 4.6.0 and not 4.5.1 . I
thought this was a regression on the 4.5 branch and given that the branch is
now locked down for 4.5.1 the target milestone ought to be 4.5.2 and this patch
should also be backported to the 4.5 branch.


-- 

ramana at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|RESOLVED                    |REOPENED
         Resolution|FIXED                       |
            Summary|[4.5 Regression] __naked    |[4.5 only] __naked attribute
                   |attribute is broken         |is broken


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44290

[Bug target/44290] [4.5 only] __naked attribute is broken

[jiez at gcc dot gnu dot org]

------- Comment #25 from jiez at gcc dot gnu dot org  2010-07-26 14:37 -------
Ramana, I will ask for permission to commit it on 4.5 branch when it's
unfrozen.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44290

[Bug target/44290] [4.5 only] __naked attribute is broken

[jiez at gcc dot gnu dot org]

------- Comment #26 from jiez at gcc dot gnu dot org  2010-07-27 17:34 -------
Subject: Bug 44290

Author: jiez
Date: Tue Jul 27 17:33:30 2010
New Revision: 162579

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=162579
Log:
        PR target/44290
        Revert
        2010-07-23  Jie Zhang  <jie@codesourcery.com>
        * tree-sra.c (ipa_sra_preliminary_function_checks): Return
        false if ! tree_versionable_function_p.

Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/tree-sra.c


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44290

[Bug target/44290] [4.5 only] __naked attribute is broken

[rguenth at gcc dot gnu dot org]

------- Comment #27 from rguenth at gcc dot gnu dot org  2010-07-31 09:29 -------
GCC 4.5.1 is being released, adjusting target milestone.


-- 

rguenth at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|4.5.1                       |4.5.2


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44290