objtool,x86: Fix uaccess PUSHF/POPF validation
Commit ab234a26 ("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 ea24213d ("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 c9c324dc ("objtool: Support stack layout changes in alternatives") makes that we can actually use stack-ops in alternatives, which means we can revert 1ff865e3 ("x86,smap: Fix smap_{save,restore}() alternatives"). That in turn means we can limit the PUSHF/POPF handling of ea24213d to those instructions that are in alternatives. Fixes: ab234a26 ("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
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