diff mbox series

arm64/fp: Don't corrupt FPMR when streaming mode changes

Message ID 20241106-arm64-fpmr-context-switch-v1-1-e6dbad4acd05@kernel.org (mailing list archive)
State New
Headers show
Series arm64/fp: Don't corrupt FPMR when streaming mode changes | expand

Commit Message

Mark Brown Nov. 6, 2024, 11:18 p.m. UTC 
When we enter or exit streaming more FPMR is reset to 0.  This means
that when restoring the floating point state from memory we need to
restore FPMR after we restore SVCR, otherwise if we are entering or
exiting streaming mode as part of loading the new state the value of
FPMR will be corrupted.

Fixes: 203f2b95a882 ("arm64/fpsimd: Support FEAT_FPMR")
Signed-off-by: Mark Brown <broonie@kernel.org>
---
 arch/arm64/kernel/fpsimd.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)


---
base-commit: 8e929cb546ee42c9a61d24fae60605e9e3192354
change-id: 20241106-arm64-fpmr-context-switch-5b48c147c3d0

Best regards,
diff mbox series

Patch

diff --git a/arch/arm64/kernel/fpsimd.c b/arch/arm64/kernel/fpsimd.c
index 77006df20a75aee7c991cf116b6d06bfe953d1a4..b26d93a444ce6cb2a0f1759240cb1fe88e7c76a0 100644
--- a/arch/arm64/kernel/fpsimd.c
+++ b/arch/arm64/kernel/fpsimd.c
@@ -359,9 +359,6 @@  static void task_fpsimd_load(void)
 	WARN_ON(preemptible());
 	WARN_ON(test_thread_flag(TIF_KERNEL_FPSTATE));
 
-	if (system_supports_fpmr())
-		write_sysreg_s(current->thread.uw.fpmr, SYS_FPMR);
-
 	if (system_supports_sve() || system_supports_sme()) {
 		switch (current->thread.fp_type) {
 		case FP_STATE_FPSIMD:
@@ -413,6 +410,9 @@  static void task_fpsimd_load(void)
 			restore_ffr = system_supports_fa64();
 	}
 
+	if (system_supports_fpmr())
+		write_sysreg_s(current->thread.uw.fpmr, SYS_FPMR);
+
 	if (restore_sve_regs) {
 		WARN_ON_ONCE(current->thread.fp_type != FP_STATE_SVE);
 		sve_load_state(sve_pffr(&current->thread),