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Commit da2e9e1f authored by Jakub Jelinek's avatar Jakub Jelinek Committed by Linus Torvalds
Browse files

[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: default avatarJakub 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: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 97db7fbf

arch/i386/kernel/vsyscall-sigreturn.S

+1 −1
Original line number Diff line number Diff line
@@ -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 */

arch/powerpc/kernel/vdso32/sigtramp.S

+1 −1
Original line number Diff line number Diff line
@@ -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 */

arch/powerpc/kernel/vdso64/sigtramp.S

+1 −1
Original line number Diff line number Diff line
@@ -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 */

arch/x86_64/ia32/vsyscall-sigreturn.S

+21 −2
Original line number Diff line number Diff line
@@ -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