x86/entry: Fixup bad_iret vs noinstr
vmlinux.o: warning: objtool: fixup_bad_iret()+0x8e: call to memcpy() leaves .noinstr.text section Worse, when KASAN there is no telling what memcpy() actually is. Force the use of __memcpy() which is our assmebly implementation. Reported-by: Marco Elver <elver@google.com> Suggested-by: Marco Elver <elver@google.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Tested-by: Marco Elver <elver@google.com> Link: https://lkml.kernel.org/r/20200618144801.760070502@infradead.org
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@ -690,13 +690,13 @@ struct bad_iret_stack *fixup_bad_iret(struct bad_iret_stack *s)
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(struct bad_iret_stack *)__this_cpu_read(cpu_tss_rw.x86_tss.sp0) - 1;
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/* Copy the IRET target to the temporary storage. */
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memcpy(&tmp.regs.ip, (void *)s->regs.sp, 5*8);
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__memcpy(&tmp.regs.ip, (void *)s->regs.sp, 5*8);
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/* Copy the remainder of the stack from the current stack. */
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memcpy(&tmp, s, offsetof(struct bad_iret_stack, regs.ip));
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__memcpy(&tmp, s, offsetof(struct bad_iret_stack, regs.ip));
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/* Update the entry stack */
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memcpy(new_stack, &tmp, sizeof(tmp));
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__memcpy(new_stack, &tmp, sizeof(tmp));
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BUG_ON(!user_mode(&new_stack->regs));
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return new_stack;
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@ -8,6 +8,8 @@
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#include <asm/alternative-asm.h>
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#include <asm/export.h>
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.pushsection .noinstr.text, "ax"
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/*
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* We build a jump to memcpy_orig by default which gets NOPped out on
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* the majority of x86 CPUs which set REP_GOOD. In addition, CPUs which
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@ -184,6 +186,8 @@ SYM_FUNC_START_LOCAL(memcpy_orig)
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retq
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SYM_FUNC_END(memcpy_orig)
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.popsection
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#ifndef CONFIG_UML
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MCSAFE_TEST_CTL
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