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target/arm: Allow FPCR bits that aren't in FPSCR

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In order to allow FPCR bits that aren't in the FPSCR (like the new
bits that are defined for FEAT_AFP), we need to make sure that writes
to the FPSCR only write to the bits of FPCR that are architecturally
mapped, and not the others.

Implement this with a new function vfp_set_fpcr_masked() which
takes a mask of which bits to update.

(We could do the same for FPSR, but we leave that until we actually
are likely to need it.)

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20240628142347.1283015-10-peter.maydell@linaro.org
This commit is contained in:
Peter Maydell 2024-06-28 15:23:47 +01:00
parent db397a81ee
commit a8ab8706d4
1 changed files with 34 additions and 20 deletions
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26
target/arm/vfp_helper.c
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@ -113,11 +113,12 @@ static void vfp_set_fpsr_to_host(CPUARMState *env, uint32_t val)
set_float_exception_flags(0, &env->vfp.standard_fp_status_f16); set_float_exception_flags(0, &env->vfp.standard_fp_status_f16);
} }
static void vfp_set_fpcr_to_host(CPUARMState *env, uint32_t val) static void vfp_set_fpcr_to_host(CPUARMState *env, uint32_t val, uint32_t mask)
{ {
uint64_t changed = env->vfp.fpcr; uint64_t changed = env->vfp.fpcr;
changed ^= val; changed ^= val;
changed &= mask;
if (changed & (3 << 22)) { if (changed & (3 << 22)) {
int i = (val >> 22) & 3; int i = (val >> 22) & 3;
switch (i) { switch (i) {
@ -167,7 +168,7 @@ static void vfp_set_fpsr_to_host(CPUARMState *env, uint32_t val)
{ {
} }
static void vfp_set_fpcr_to_host(CPUARMState *env, uint32_t val) static void vfp_set_fpcr_to_host(CPUARMState *env, uint32_t val, uint32_t mask)
{ {
} }
@ -239,8 +240,13 @@ void vfp_set_fpsr(CPUARMState *env, uint32_t val)
env->vfp.fpsr = val; env->vfp.fpsr = val;
} }
void vfp_set_fpcr(CPUARMState *env, uint32_t val) static void vfp_set_fpcr_masked(CPUARMState *env, uint32_t val, uint32_t mask)
{ {
/*
* We only set FPCR bits defined by mask, and leave the others alone.
* We assume the mask is sensible (e.g. doesn't try to set only
* part of a field)
*/
ARMCPU *cpu = env_archcpu(env); ARMCPU *cpu = env_archcpu(env);
/* When ARMv8.2-FP16 is not supported, FZ16 is RES0. */ /* When ARMv8.2-FP16 is not supported, FZ16 is RES0. */
@ -248,8 +254,9 @@ void vfp_set_fpcr(CPUARMState *env, uint32_t val)
val &= ~FPCR_FZ16; val &= ~FPCR_FZ16;
} }
vfp_set_fpcr_to_host(env, val); vfp_set_fpcr_to_host(env, val, mask);
if (mask & (FPCR_LEN_MASK | FPCR_STRIDE_MASK)) {
if (!arm_feature(env, ARM_FEATURE_M)) { if (!arm_feature(env, ARM_FEATURE_M)) {
/* /*
* Short-vector length and stride; on M-profile these bits * Short-vector length and stride; on M-profile these bits
@ -265,6 +272,7 @@ void vfp_set_fpcr(CPUARMState *env, uint32_t val)
env->v7m.ltpsize = extract32(val, FPCR_LTPSIZE_SHIFT, env->v7m.ltpsize = extract32(val, FPCR_LTPSIZE_SHIFT,
FPCR_LTPSIZE_LENGTH); FPCR_LTPSIZE_LENGTH);
} }
}
/* /*
* We don't implement trapped exception handling, so the * We don't implement trapped exception handling, so the
@ -276,12 +284,18 @@ void vfp_set_fpcr(CPUARMState *env, uint32_t val)
* bits. * bits.
*/ */
val &= FPCR_AHP | FPCR_DN | FPCR_FZ | FPCR_RMODE_MASK | FPCR_FZ16; val &= FPCR_AHP | FPCR_DN | FPCR_FZ | FPCR_RMODE_MASK | FPCR_FZ16;
env->vfp.fpcr = val; env->vfp.fpcr &= ~mask;
env->vfp.fpcr |= val;
}
void vfp_set_fpcr(CPUARMState *env, uint32_t val)
{
vfp_set_fpcr_masked(env, val, MAKE_64BIT_MASK(0, 32));
} }
void HELPER(vfp_set_fpscr)(CPUARMState *env, uint32_t val) void HELPER(vfp_set_fpscr)(CPUARMState *env, uint32_t val)
{ {
vfp_set_fpcr(env, val & FPSCR_FPCR_MASK); vfp_set_fpcr_masked(env, val, FPSCR_FPCR_MASK);
vfp_set_fpsr(env, val & FPSCR_FPSR_MASK); vfp_set_fpsr(env, val & FPSCR_FPSR_MASK);
} }