6.6-stable review patch. If anyone has any objections, please let me know.
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From: Jens Remus jremus@linux.ibm.com
[ Upstream commit b961ec10b9f9719987470236feb50c967db5a652 ]
The return-address (RA) register r14 is specified as volatile in the s390x ELF ABI [1]. Nevertheless proper CFI directives must be provided for an unwinder to restore the return address, if the RA register value is changed from its value at function entry, as it is the case.
[1]: s390x ELF ABI, https://github.com/IBM/s390x-abi/releases
Fixes: 4bff8cb54502 ("s390: convert to GENERIC_VDSO") Signed-off-by: Jens Remus jremus@linux.ibm.com Acked-by: Heiko Carstens hca@linux.ibm.com Signed-off-by: Alexander Gordeev agordeev@linux.ibm.com Signed-off-by: Sasha Levin sashal@kernel.org --- arch/s390/include/asm/dwarf.h | 1 + arch/s390/kernel/vdso64/vdso_user_wrapper.S | 2 ++ 2 files changed, 3 insertions(+)
diff --git a/arch/s390/include/asm/dwarf.h b/arch/s390/include/asm/dwarf.h index 4f21ae561e4dd..390906b8e386e 100644 --- a/arch/s390/include/asm/dwarf.h +++ b/arch/s390/include/asm/dwarf.h @@ -9,6 +9,7 @@ #define CFI_DEF_CFA_OFFSET .cfi_def_cfa_offset #define CFI_ADJUST_CFA_OFFSET .cfi_adjust_cfa_offset #define CFI_RESTORE .cfi_restore +#define CFI_REL_OFFSET .cfi_rel_offset
#ifdef CONFIG_AS_CFI_VAL_OFFSET #define CFI_VAL_OFFSET .cfi_val_offset diff --git a/arch/s390/kernel/vdso64/vdso_user_wrapper.S b/arch/s390/kernel/vdso64/vdso_user_wrapper.S index 57f62596e53b9..85247ef5a41b8 100644 --- a/arch/s390/kernel/vdso64/vdso_user_wrapper.S +++ b/arch/s390/kernel/vdso64/vdso_user_wrapper.S @@ -24,8 +24,10 @@ __kernel_\func: CFI_DEF_CFA_OFFSET (STACK_FRAME_OVERHEAD + WRAPPER_FRAME_SIZE) CFI_VAL_OFFSET 15, -STACK_FRAME_OVERHEAD stg %r14,STACK_FRAME_OVERHEAD(%r15) + CFI_REL_OFFSET 14, STACK_FRAME_OVERHEAD brasl %r14,__s390_vdso_\func lg %r14,STACK_FRAME_OVERHEAD(%r15) + CFI_RESTORE 14 aghi %r15,WRAPPER_FRAME_SIZE CFI_DEF_CFA_OFFSET STACK_FRAME_OVERHEAD CFI_RESTORE 15