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Commit da2e9e1ff40c863a12803c32209baaded3512433

Authored by Jakub Jelinek
Committed by Linus Torvalds
1 parent 97db7fbfc7
Exists in master and in 7 other branches imx_3.0.35_4.1.0, imx_3.10.17_1.0.1_ga, imx_3.10.53_1.1.0_ga, imx_3.14.28_1.0.0_ga, smarc-imx_3.10.53_1.1.0_ga, smarc-imx_3.14.28_1.0.0_ga, smarc-l5.0.0_1.0.0-ga

[PATCH] Mark unwind info for signal trampolines in vDSOs 

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>

Showing 4 changed files with 24 additions and 5 deletions Side-by-side Diff

arch/i386/kernel/vsyscall-sigreturn.S
Diff comments   View file @ da2e9e1
... ... @@ -44,7 +44,7 @@
44 44 .LSTARTCIEDLSI1:
45 45 .long 0 /* CIE ID */
46 46 .byte 1 /* Version number */
47   - .string "zR" /* NUL-terminated augmentation string */
  47 + .string "zRS" /* NUL-terminated augmentation string */
48 48 .uleb128 1 /* Code alignment factor */
49 49 .sleb128 -4 /* Data alignment factor */
50 50 .byte 8 /* Return address register column */
arch/powerpc/kernel/vdso32/sigtramp.S
Diff comments   View file @ da2e9e1
... ... @@ -261,7 +261,7 @@
261 261 .Lcie_start:
262 262 .long 0 /* CIE ID */
263 263 .byte 1 /* Version number */
264   - .string "zR" /* NUL-terminated augmentation string */
  264 + .string "zRS" /* NUL-terminated augmentation string */
265 265 .uleb128 4 /* Code alignment factor */
266 266 .sleb128 -4 /* Data alignment factor */
267 267 .byte 67 /* Return address register column, ap */
arch/powerpc/kernel/vdso64/sigtramp.S
Diff comments   View file @ da2e9e1
... ... @@ -263,7 +263,7 @@
263 263 .Lcie_start:
264 264 .long 0 /* CIE ID */
265 265 .byte 1 /* Version number */
266   - .string "zR" /* NUL-terminated augmentation string */
  266 + .string "zRS" /* NUL-terminated augmentation string */
267 267 .uleb128 4 /* Code alignment factor */
268 268 .sleb128 -8 /* Data alignment factor */
269 269 .byte 67 /* Return address register column, ap */
arch/x86_64/ia32/vsyscall-sigreturn.S
Diff comments   View file @ da2e9e1
... ... @@ -32,9 +32,28 @@
32 32 .size __kernel_rt_sigreturn,.-.LSTART_rt_sigreturn
33 33  
34 34 .section .eh_frame,"a",@progbits
  35 +.LSTARTFRAMES:
  36 + .long .LENDCIES-.LSTARTCIES
  37 +.LSTARTCIES:
  38 + .long 0 /* CIE ID */
  39 + .byte 1 /* Version number */
  40 + .string "zRS" /* NUL-terminated augmentation string */
  41 + .uleb128 1 /* Code alignment factor */
  42 + .sleb128 -4 /* Data alignment factor */
  43 + .byte 8 /* Return address register column */
  44 + .uleb128 1 /* Augmentation value length */
  45 + .byte 0x1b /* DW_EH_PE_pcrel|DW_EH_PE_sdata4. */
  46 + .byte 0x0c /* DW_CFA_def_cfa */
  47 + .uleb128 4
  48 + .uleb128 4
  49 + .byte 0x88 /* DW_CFA_offset, column 0x8 */
  50 + .uleb128 1
  51 + .align 4
  52 +.LENDCIES:
  53 +
35 54 .long .LENDFDE2-.LSTARTFDE2 /* Length FDE */
36 55 .LSTARTFDE2:
37   - .long .LSTARTFDE2-.LSTARTFRAME /* CIE pointer */
  56 + .long .LSTARTFDE2-.LSTARTFRAMES /* CIE pointer */
38 57 /* HACK: The dwarf2 unwind routines will subtract 1 from the
39 58 return address to get an address in the middle of the
40 59 presumed call instruction. Since we didn't get here via
... ... @@ -97,7 +116,7 @@
97 116  
98 117 .long .LENDFDE3-.LSTARTFDE3 /* Length FDE */
99 118 .LSTARTFDE3:
100   - .long .LSTARTFDE3-.LSTARTFRAME /* CIE pointer */
  119 + .long .LSTARTFDE3-.LSTARTFRAMES /* CIE pointer */
101 120 /* HACK: See above wrt unwind library assumptions. */
102 121 .long .LSTART_rt_sigreturn-1-. /* PC-relative start address */
103 122 .long .LEND_rt_sigreturn-.LSTART_rt_sigreturn+1