diff options
| author | Hendrik Brueckner <brueckner@linux.vnet.ibm.com> | 2017-11-20 11:46:13 +0100 |
|---|---|---|
| committer | Martin Schwidefsky <schwidefsky@de.ibm.com> | 2017-12-13 10:51:36 +0100 |
| commit | 7bceec4e58ee23be653c0dd366479d6cb64ae686 (patch) | |
| tree | cd285499f296c534522f812c6d4af6febd7aa8a2 /arch/s390/kernel/vdso64/clock_getres.S | |
| parent | bc3703f21cec8a2ac6a64f6fb3686fbcb1ba1513 (diff) | |
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.S | 4 |
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 |