From 6c22c98637602f89beb40c43cfb3d764b71a54c6 Mon Sep 17 00:00:00 2001 From: Heiko Carstens Date: Fri, 10 Jun 2016 09:57:05 +0200 Subject: s390: avoid extable collisions We have some inline assemblies where the extable entry points to a label at the end of an inline assembly which is not followed by an instruction. On the other hand we have also inline assemblies where the extable entry points to the first instruction of an inline assembly. If a first type inline asm (extable point to empty label at the end) would be directly followed by a second type inline asm (extable points to first instruction) then we would have two different extable entries that point to the same instruction but would have a different target address. This can lead to quite random behaviour, depending on sorting order. I verified that we currently do not have such collisions within the kernel. However to avoid such subtle bugs add a couple of nop instructions to those inline assemblies which contain an extable that points to an empty label. Signed-off-by: Heiko Carstens Signed-off-by: Martin Schwidefsky --- arch/s390/hypfs/hypfs_diag.c | 2 +- arch/s390/hypfs/hypfs_vm.c | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-) (limited to 'arch/s390/hypfs') diff --git a/arch/s390/hypfs/hypfs_diag.c b/arch/s390/hypfs/hypfs_diag.c index 045035796ca7..27779f0743ac 100644 --- a/arch/s390/hypfs/hypfs_diag.c +++ b/arch/s390/hypfs/hypfs_diag.c @@ -344,7 +344,7 @@ static inline int __diag204(unsigned long subcode, unsigned long size, void *add asm volatile( " diag %2,%0,0x204\n" - "0:\n" + "0: nopr %%r7\n" EX_TABLE(0b,0b) : "+d" (_subcode), "+d" (_size) : "d" (addr) : "memory"); if (_subcode) diff --git a/arch/s390/hypfs/hypfs_vm.c b/arch/s390/hypfs/hypfs_vm.c index 44feac38ccfc..012919d9833b 100644 --- a/arch/s390/hypfs/hypfs_vm.c +++ b/arch/s390/hypfs/hypfs_vm.c @@ -70,7 +70,7 @@ static int diag2fc(int size, char* query, void *addr) diag_stat_inc(DIAG_STAT_X2FC); asm volatile( " diag %0,%1,0x2fc\n" - "0:\n" + "0: nopr %%r7\n" EX_TABLE(0b,0b) : "=d" (residual_cnt), "+d" (rc) : "0" (&parm_list) : "memory"); -- cgit v1.2.3