5.15-stable review patch. If anyone has any objections, please let me know.
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From: Dave Hansen dave.hansen@linux.intel.com
[ Upstream commit 1cec9ac2d071cfd2da562241aab0ef701355762a ]
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: d5c8028b4788 ("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.in... [ Replace fpu_reset_from_exception_fixup() with __restore_fpregs_from_fpstate() ] Signed-off-by: Sasha Levin sashal@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/x86/mm/extable.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-)
--- a/arch/x86/mm/extable.c +++ b/arch/x86/mm/extable.c @@ -60,13 +60,12 @@ static bool ex_handler_fault(const struc static bool ex_handler_fprestore(const struct exception_table_entry *fixup, struct pt_regs *regs) { - regs->ip = ex_fixup_addr(fixup); - WARN_ONCE(1, "Bad FPU state detected at %pB, reinitializing FPU registers.", (void *)instruction_pointer(regs));
__restore_fpregs_from_fpstate(&init_fpstate, xfeatures_mask_fpstate()); - return true; + + return ex_handler_default(fixup, regs); }
static bool ex_handler_uaccess(const struct exception_table_entry *fixup,