Hi!
The following patch marks 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).
Please apply.
Signed-off-by: Jakub Jelinek <[email protected]>
--- linux-2.6.15/arch/i386/kernel/vsyscall-sigreturn.S.jj 2006-01-02 22:21:10.000000000 -0500
+++ linux-2.6.15/arch/i386/kernel/vsyscall-sigreturn.S 2006-02-21 05:10:31.000000000 -0500
@@ -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 */
--- linux-2.6.15/arch/x86_64/ia32/vsyscall-sigreturn.S.jj 2006-01-02 22:21:10.000000000 -0500
+++ linux-2.6.15/arch/x86_64/ia32/vsyscall-sigreturn.S 2006-02-21 05:17:41.000000000 -0500
@@ -31,8 +31,27 @@ __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
@@ -96,7 +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
--- linux-2.6.15/arch/powerpc/kernel/vdso32/sigtramp.S.jj 2006-01-02 22:21:10.000000000 -0500
+++ linux-2.6.15/arch/powerpc/kernel/vdso32/sigtramp.S 2006-02-21 05:24:12.000000000 -0500
@@ -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 */
--- linux-2.6.15/arch/powerpc/kernel/vdso64/sigtramp.S.jj 2006-01-02 22:21:10.000000000 -0500
+++ linux-2.6.15/arch/powerpc/kernel/vdso64/sigtramp.S 2006-02-21 05:28:28.000000000 -0500
@@ -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 */
Jakub