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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 /tools/objtool
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 'tools/objtool')
-rw-r--r--tools/objtool/check.c3
1 files changed, 3 insertions, 0 deletions
diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 068cdb41f76f..5e5388a38e2a 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -2442,6 +2442,9 @@ static int handle_insn_ops(struct instruction *insn, struct insn_state *state)
if (update_cfi_state(insn, &state->cfi, op))
return 1;
+ if (!insn->alt_group)
+ continue;
+
if (op->dest.type == OP_DEST_PUSHF) {
if (!state->uaccess_stack) {
state->uaccess_stack = 1;