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[Stable-7.2.16,32/33] target/arm: arm_reset_sve_state() should set FPSR, not FPCR

Message ID 20250207072343.2109513-1-mjt@tls.msk.ru
State New
Headers show
Series None | expand

Commit Message

Michael Tokarev Feb. 7, 2025, 7:23 a.m. UTC 
From: Peter Maydell <peter.maydell@linaro.org>

The pseudocode ResetSVEState() does:
    FPSR = ZeroExtend(0x0800009f<31:0>, 64);
but QEMU's arm_reset_sve_state() called vfp_set_fpcr() by accident.

Before the advent of FEAT_AFP, this was only setting a collection of
RES0 bits, which vfp_set_fpsr() would then ignore, so the only effect
was that we didn't actually set the FPSR the way we are supposed to
do.  Once FEAT_AFP is implemented, setting the bottom bits of FPSR
will change the floating point behaviour.

Call vfp_set_fpsr(), as we ought to.

(Note for stable backports: commit 7f2a01e7368f9 moved this function
from sme_helper.c to helper.c, but it had the same bug before the
move too.)

Cc: qemu-stable@nongnu.org
Fixes: f84734b87461 ("target/arm: Implement SMSTART, SMSTOP")
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20250124162836.2332150-4-peter.maydell@linaro.org
(cherry picked from commit 1edc3d43f20df0d04f8d00b906ba19fed37512a5)
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
(it is in sme_helper.c in 7.2, not in helper.c)
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Patch

diff --git a/target/arm/sme_helper.c b/target/arm/sme_helper.c
index 98a4840970..fd5625c87e 100644
--- a/target/arm/sme_helper.c
+++ b/target/arm/sme_helper.c
@@ -35,7 +35,7 @@  void arm_reset_sve_state(CPUARMState *env)
     memset(env->vfp.zregs, 0, sizeof(env->vfp.zregs));
     /* Recall that FFR is stored as pregs[16]. */
     memset(env->vfp.pregs, 0, sizeof(env->vfp.pregs));
-    vfp_set_fpcr(env, 0x0800009f);
+    vfp_set_fpsr(env, 0x0800009f);
 }
 
 void helper_set_pstate_sm(CPUARMState *env, uint32_t i)