[PATCH tip/x86/fpu 6/6] x86/fpu: shift fpregs_assert_state_consistent() from arch_exit_work() to its caller

From: Oleg Nesterov
Date: Sat May 03 2025 - 10:40:31 EST


If CONFIG_X86_DEBUG_FPU=Y, arch_exit_to_user_mode_prepare() calls
arch_exit_work() even if ti_work == 0. There only reason is that we
want to call fpregs_assert_state_consistent() if TIF_NEED_FPU_LOAD
is not set.

This looks confusing. arch_exit_to_user_mode_prepare() can just call
fpregs_assert_state_consistent() unconditionally, it depends on
CONFIG_X86_DEBUG_FPU and checks TIF_NEED_FPU_LOAD itself.

Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx>
---
arch/x86/include/asm/entry-common.h | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/arch/x86/include/asm/entry-common.h b/arch/x86/include/asm/entry-common.h
index 77d20555e04d..d535a97c7284 100644
--- a/arch/x86/include/asm/entry-common.h
+++ b/arch/x86/include/asm/entry-common.h
@@ -53,7 +53,6 @@ static inline void arch_exit_work(unsigned long ti_work)
if (unlikely(ti_work & _TIF_IO_BITMAP))
tss_update_io_bitmap();

- fpregs_assert_state_consistent();
if (unlikely(ti_work & _TIF_NEED_FPU_LOAD))
switch_fpu_return();
}
@@ -61,7 +60,9 @@ static inline void arch_exit_work(unsigned long ti_work)
static inline void arch_exit_to_user_mode_prepare(struct pt_regs *regs,
unsigned long ti_work)
{
- if (IS_ENABLED(CONFIG_X86_DEBUG_FPU) || unlikely(ti_work))
+ fpregs_assert_state_consistent();
+
+ if (unlikely(ti_work))
arch_exit_work(ti_work);

fred_update_rsp0();
--
2.25.1.362.g51ebf55