s390/vdso: Add CFI for RA register to asm macro vdso_func

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>

diff --git a/arch/s390/include/asm/dwarf.h b/arch/s390/include/asm/dwarf.h
index 4f21ae561e4ddc7af7bc7a21f848f0fe4315ab59..390906b8e386e609f760d891484133b1c0fbea79 100644 (file)
--- 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 57f62596e53b958a2737f23f1985e5154179fd9e..85247ef5a41b89a390d3290cefb785c6c5a81ad6 100644 (file)
--- 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