arm64/signal: Don't assume that TIF_SVE means we saved SVE state

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@kernel.org>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20240130-arm64-sve-signal-regs-v2-1-9fc6f9502782@kernel.org
Signed-off-by: Will Deacon <will@kernel.org>

diff --git a/arch/arm64/kernel/fpsimd.c b/arch/arm64/kernel/fpsimd.c
index a5dc6f764195847251dc25c196304cbef44d8850..25ceaee6b025da204857af8faeadae2fa83f128c 100644 (file)
--- a/arch/arm64/kernel/fpsimd.c
+++ b/arch/arm64/kernel/fpsimd.c
@@ -1635,7 +1635,7 @@ 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);
 }
 

diff --git a/arch/arm64/kernel/signal.c b/arch/arm64/kernel/signal.c
index 0e8beb3349ea2a1aae6340f879f78dd568e04f51..425b1bc17a3f6dc3237e81fabcb35d774f1aa9d1 100644 (file)
--- a/arch/arm64/kernel/signal.c
+++ b/arch/arm64/kernel/signal.c
@@ -242,7 +242,7 @@ static int preserve_sve_context(struct sve_context __user *ctx)
                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 rt_sigframe_user_layout *user,
        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(&current->thread)) {
                        int vl = max(sve_max_vl(), sme_max_vl());