summaryrefslogtreecommitdiff
path: root/arch
diff options
context:
space:
mode:
authorPeter Zijlstra <peterz@infradead.org>2021-03-08 17:46:04 +0300
committerPeter Zijlstra <peterz@infradead.org>2021-03-12 11:15:49 +0300
commitba08abca66d46381df60842f64f70099d5482b92 (patch)
tree4c95d9c8d8a57e79b4942d841fb45b1c787f7c90 /arch
parenta38fd8748464831584a19438cbb3082b5a2dab15 (diff)
downloadlinux-ba08abca66d46381df60842f64f70099d5482b92.tar.xz
objtool,x86: Fix uaccess PUSHF/POPF validation
Commit ab234a260b1f ("x86/pv: Rework arch_local_irq_restore() to not use popf") replaced "push %reg; popf" with something like: "test $0x200, %reg; jz 1f; sti; 1:", which breaks the pushf/popf symmetry that commit ea24213d8088 ("objtool: Add UACCESS validation") relies on. The result is: drivers/gpu/drm/amd/amdgpu/si.o: warning: objtool: si_common_hw_init()+0xf36: PUSHF stack exhausted Meanwhile, commit c9c324dc22aa ("objtool: Support stack layout changes in alternatives") makes that we can actually use stack-ops in alternatives, which means we can revert 1ff865e343c2 ("x86,smap: Fix smap_{save,restore}() alternatives"). That in turn means we can limit the PUSHF/POPF handling of ea24213d8088 to those instructions that are in alternatives. Fixes: ab234a260b1f ("x86/pv: Rework arch_local_irq_restore() to not use popf") Reported-by: Borislav Petkov <bp@alien8.de> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Josh Poimboeuf <jpoimboe@redhat.com> Link: https://lkml.kernel.org/r/YEY4rIbQYa5fnnEp@hirez.programming.kicks-ass.net
Diffstat (limited to 'arch')
-rw-r--r--arch/x86/include/asm/smap.h10
1 files changed, 4 insertions, 6 deletions
diff --git a/arch/x86/include/asm/smap.h b/arch/x86/include/asm/smap.h
index 8b58d6975d5d..0bc9b0895f33 100644
--- a/arch/x86/include/asm/smap.h
+++ b/arch/x86/include/asm/smap.h
@@ -58,9 +58,8 @@ static __always_inline unsigned long smap_save(void)
unsigned long flags;
asm volatile ("# smap_save\n\t"
- ALTERNATIVE("jmp 1f", "", X86_FEATURE_SMAP)
- "pushf; pop %0; " __ASM_CLAC "\n\t"
- "1:"
+ ALTERNATIVE("", "pushf; pop %0; " __ASM_CLAC "\n\t",
+ X86_FEATURE_SMAP)
: "=rm" (flags) : : "memory", "cc");
return flags;
@@ -69,9 +68,8 @@ static __always_inline unsigned long smap_save(void)
static __always_inline void smap_restore(unsigned long flags)
{
asm volatile ("# smap_restore\n\t"
- ALTERNATIVE("jmp 1f", "", X86_FEATURE_SMAP)
- "push %0; popf\n\t"
- "1:"
+ ALTERNATIVE("", "push %0; popf\n\t",
+ X86_FEATURE_SMAP)
: : "g" (flags) : "memory", "cc");
}