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authorHendrik Brueckner <brueckner@linux.vnet.ibm.com>2017-11-20 11:46:13 +0100
committerMartin Schwidefsky <schwidefsky@de.ibm.com>2017-12-13 10:51:36 +0100
commit7bceec4e58ee23be653c0dd366479d6cb64ae686 (patch)
treecd285499f296c534522f812c6d4af6febd7aa8a2 /arch/s390/kernel/vdso64/clock_getres.S
parents390/kernel: emit CFI data in .debug_frame and discard .eh_frame sections (diff)
downloadlinux-dev-7bceec4e58ee23be653c0dd366479d6cb64ae686.tar.xz
linux-dev-7bceec4e58ee23be653c0dd366479d6cb64ae686.zip
s390/vdso: revise CFI annotations of vDSO functions
Revise and add CFI CFA and register rule annotations to the vDSO functions for proper stack unwinding and debugging. Because glibc might call the vDSO in special ways, the vDSO code does not rely on a stack frame created by the caller. The TOD clock value can be therefore not stored in the pre-allocated stack area and additional stack space is required. To correctly annotate these situations with CFI, the .cfi_val_offset directive is required to create relative offsets on the value of the stack register %r15. Because the .cfi_val_offset directive is available with recent GNU assembler versions only, additional checks are necessary. Note that if the vDSO is assembled with an older assembler version, stack unwinding and debugging from within the vDSO code might not be possible. Signed-off-by: Hendrik Brueckner <brueckner@linux.vnet.ibm.com> Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Diffstat (limited to 'arch/s390/kernel/vdso64/clock_getres.S')
-rw-r--r--arch/s390/kernel/vdso64/clock_getres.S4
1 files changed, 2 insertions, 2 deletions
diff --git a/arch/s390/kernel/vdso64/clock_getres.S b/arch/s390/kernel/vdso64/clock_getres.S
index 5b0d9c380de2..081435398e0a 100644
--- a/arch/s390/kernel/vdso64/clock_getres.S
+++ b/arch/s390/kernel/vdso64/clock_getres.S
@@ -16,7 +16,7 @@
.globl __kernel_clock_getres
.type __kernel_clock_getres,@function
__kernel_clock_getres:
- .cfi_startproc
+ CFI_STARTPROC
larl %r1,4f
cghi %r2,__CLOCK_REALTIME_COARSE
je 0f
@@ -44,7 +44,7 @@ __kernel_clock_getres:
2: lghi %r1,__NR_clock_getres /* fallback to svc */
svc 0
br %r14
+ CFI_ENDPROC
3: .quad __CLOCK_REALTIME_RES
4: .quad __CLOCK_COARSE_RES
- .cfi_endproc
.size __kernel_clock_getres,.-__kernel_clock_getres