6.6-stable review patch. If anyone has any objections, please let me know.
------------------
From: Mark Brown <broonie@xxxxxxxxxx>
commit 61da7c8e2a602f66be578cbbcebe8638c10e0f48 upstream.
When we are in a syscall we will only save the FPSIMD subset even though
the task still has access to the full register set, and on context switch
we will only remove TIF_SVE when loading the register state. This means
that the signal handling code should not assume that TIF_SVE means that
the register state is stored in SVE format, it should instead check the
format that was recorded during save.
Fixes: 8c845e273104 ("arm64/sve: Leave SVE enabled on syscall if we don't context switch")
Signed-off-by: Mark Brown <broonie@xxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Link: https://lore.kernel.org/r/20240130-arm64-sve-signal-regs-v2-1-9fc6f9502782@xxxxxxxxxx
Signed-off-by: Will Deacon <will@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/arm64/kernel/fpsimd.c | 2 +-
arch/arm64/kernel/signal.c | 4 ++--
2 files changed, 3 insertions(+), 3 deletions(-)
--- a/arch/arm64/kernel/fpsimd.c
+++ b/arch/arm64/kernel/fpsimd.c
@@ -1686,7 +1686,7 @@ void fpsimd_preserve_current_state(void)
void fpsimd_signal_preserve_current_state(void)
{
fpsimd_preserve_current_state();
- if (test_thread_flag(TIF_SVE))
+ if (current->thread.fp_type == FP_STATE_SVE)
sve_to_fpsimd(current);
}
--- a/arch/arm64/kernel/signal.c
+++ b/arch/arm64/kernel/signal.c
@@ -242,7 +242,7 @@ static int preserve_sve_context(struct s
vl = task_get_sme_vl(current);
vq = sve_vq_from_vl(vl);
flags |= SVE_SIG_FLAG_SM;
- } else if (test_thread_flag(TIF_SVE)) {
+ } else if (current->thread.fp_type == FP_STATE_SVE) {
vq = sve_vq_from_vl(vl);
}
@@ -878,7 +878,7 @@ static int setup_sigframe_layout(struct
if (system_supports_sve() || system_supports_sme()) {
unsigned int vq = 0;
- if (add_all || test_thread_flag(TIF_SVE) ||
+ if (add_all || current->thread.fp_type == FP_STATE_SVE ||
thread_sm_enabled(¤t->thread)) {
int vl = max(sve_max_vl(), sme_max_vl());
