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hansendcgregkh
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x86/fpu: Delay instruction pointer fixup until after warning
commit 1cec9ac upstream. Right now, if XRSTOR fails a console message like this is be printed: Bad FPU state detected at restore_fpregs_from_fpstate+0x9a/0x170, reinitializing FPU registers. However, the text location (...+0x9a in this case) is the instruction *AFTER* the XRSTOR. The highlighted instruction in the "Code:" dump also points one instruction late. The reason is that the "fixup" moves RIP up to pass the bad XRSTOR and keep on running after returning from the #GP handler. But it does this fixup before warning. The resulting warning output is nonsensical because it looks like the non-FPU-related instruction is #GP'ing. Do not fix up RIP until after printing the warning. Do this by using the more generic and standard ex_handler_default(). Fixes: d5c8028 ("x86/fpu: Reinitialize FPU registers if restoring FPU state fails") Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Reviewed-by: Chao Gao <chao.gao@intel.com> Acked-by: Alison Schofield <alison.schofield@intel.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc:stable@vger.kernel.org Link: https://lore.kernel.org/all/20250624210148.97126F9E%40davehans-spike.ostc.intel.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Lines changed: 2 additions & 3 deletions

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arch/x86/mm/extable.c

Lines changed: 2 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -121,13 +121,12 @@ static bool ex_handler_sgx(const struct exception_table_entry *fixup,
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static bool ex_handler_fprestore(const struct exception_table_entry *fixup,
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struct pt_regs *regs)
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{
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regs->ip = ex_fixup_addr(fixup);
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WARN_ONCE(1, "Bad FPU state detected at %pB, reinitializing FPU registers.",
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(void *)instruction_pointer(regs));
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fpu_reset_from_exception_fixup();
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return true;
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return ex_handler_default(fixup, regs);
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}
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static bool ex_handler_uaccess(const struct exception_table_entry *fixup,

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