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[PATCH] Mark unwind info for signal trampolines in vDSOs

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Mark unwind info for signal trampolines using the new S augmentation flag
introduced in: http://gcc.gnu.org/PR26208.

GCC 4.2 (or patched earlier GCC) will be able to special case unwinding
through frames right above signal trampolines.  As the augmentations start
with z flag and S is at the very end of the augmentation string, older GCCs
will just skip the S flag as unknown (that's why an augmentation flag was
chosen over say a new CFA opcode).

Signed-off-by: Jakub Jelinek <jakub@redhat.com>
Cc: Andi Kleen <ak@muc.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Jakub Jelinek 2006-03-31 02:30:28 -08:00 committed by Linus Torvalds
parent 97db7fbfc7
commit da2e9e1ff4
4 changed files with 24 additions and 5 deletions
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2
arch/i386/kernel/vsyscall-sigreturn.S
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@ -44,7 +44,7 @@ __kernel_rt_sigreturn:
.LSTARTCIEDLSI1:
.long 0 /* CIE ID */
.byte 1 /* Version number */
.string "zR" /* NUL-terminated augmentation string */
.string "zRS" /* NUL-terminated augmentation string */
.uleb128 1 /* Code alignment factor */
.sleb128 -4 /* Data alignment factor */
.byte 8 /* Return address register column */

2
arch/powerpc/kernel/vdso32/sigtramp.S
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@ -261,7 +261,7 @@ V_FUNCTION_END(__kernel_sigtramp_rt32)
.Lcie_start:
.long 0 /* CIE ID */
.byte 1 /* Version number */
.string "zR" /* NUL-terminated augmentation string */
.string "zRS" /* NUL-terminated augmentation string */
.uleb128 4 /* Code alignment factor */
.sleb128 -4 /* Data alignment factor */
.byte 67 /* Return address register column, ap */

2
arch/powerpc/kernel/vdso64/sigtramp.S
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@ -263,7 +263,7 @@ V_FUNCTION_END(__kernel_sigtramp_rt64)
.Lcie_start:
.long 0 /* CIE ID */
.byte 1 /* Version number */
.string "zR" /* NUL-terminated augmentation string */
.string "zRS" /* NUL-terminated augmentation string */
.uleb128 4 /* Code alignment factor */
.sleb128 -8 /* Data alignment factor */
.byte 67 /* Return address register column, ap */

23
arch/x86_64/ia32/vsyscall-sigreturn.S
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@ -32,9 +32,28 @@ __kernel_rt_sigreturn:
.size __kernel_rt_sigreturn,.-.LSTART_rt_sigreturn
.section .eh_frame,"a",@progbits
.LSTARTFRAMES:
.long .LENDCIES-.LSTARTCIES
.LSTARTCIES:
.long 0 /* CIE ID */
.byte 1 /* Version number */
.string "zRS" /* NUL-terminated augmentation string */
.uleb128 1 /* Code alignment factor */
.sleb128 -4 /* Data alignment factor */
.byte 8 /* Return address register column */
.uleb128 1 /* Augmentation value length */
.byte 0x1b /* DW_EH_PE_pcrel|DW_EH_PE_sdata4. */
.byte 0x0c /* DW_CFA_def_cfa */
.uleb128 4
.uleb128 4
.byte 0x88 /* DW_CFA_offset, column 0x8 */
.uleb128 1
.align 4
.LENDCIES:
.long .LENDFDE2-.LSTARTFDE2 /* Length FDE */
.LSTARTFDE2:
.long .LSTARTFDE2-.LSTARTFRAME /* CIE pointer */
.long .LSTARTFDE2-.LSTARTFRAMES /* CIE pointer */
/* HACK: The dwarf2 unwind routines will subtract 1 from the
return address to get an address in the middle of the
presumed call instruction. Since we didn't get here via
@ -97,7 +116,7 @@ __kernel_rt_sigreturn:
.long .LENDFDE3-.LSTARTFDE3 /* Length FDE */
.LSTARTFDE3:
.long .LSTARTFDE3-.LSTARTFRAME /* CIE pointer */
.long .LSTARTFDE3-.LSTARTFRAMES /* CIE pointer */
/* HACK: See above wrt unwind library assumptions. */
.long .LSTART_rt_sigreturn-1-. /* PC-relative start address */
.long .LEND_rt_sigreturn-.LSTART_rt_sigreturn+1