diff mbox series

[v2,1/3] target/arm: Correctly bound length in sve_zcr_get_valid_len

Message ID 20210723203344.968563-2-richard.henderson@linaro.org
State Superseded
Headers show
Series target/arm: Add sve-default-vector-length cpu property | expand

Commit Message

Richard Henderson July 23, 2021, 8:33 p.m. UTC
Currently, our only caller is sve_zcr_len_for_el, which has
already masked the length extracted from ZCR_ELx, so the
masking done here is a nop.  But we will shortly have uses
from other locations, where the length will be unmasked.

Saturate the length to ARM_MAX_VQ instead of truncating to
the low 4 bits.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

---
 target/arm/helper.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

-- 
2.25.1

Comments

Peter Maydell July 26, 2021, 10:57 a.m. UTC | #1
On Fri, 23 Jul 2021 at 21:36, Richard Henderson
<richard.henderson@linaro.org> wrote:
>

> Currently, our only caller is sve_zcr_len_for_el, which has

> already masked the length extracted from ZCR_ELx, so the

> masking done here is a nop.  But we will shortly have uses

> from other locations, where the length will be unmasked.

>

> Saturate the length to ARM_MAX_VQ instead of truncating to

> the low 4 bits.

>

> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

> ---


Reviewed-by: Peter Maydell <peter.maydell@linaro.org>


thanks
-- PMM
diff mbox series

Patch

diff --git a/target/arm/helper.c b/target/arm/helper.c
index 0c07ca9837..8c1d8dbce3 100644
--- a/target/arm/helper.c
+++ b/target/arm/helper.c
@@ -6461,7 +6461,9 @@  static uint32_t sve_zcr_get_valid_len(ARMCPU *cpu, uint32_t start_len)
 {
     uint32_t end_len;
 
-    end_len = start_len &= 0xf;
+    start_len = MIN(start_len, ARM_MAX_VQ - 1);
+    end_len = start_len;
+
     if (!test_bit(start_len, cpu->sve_vq_map)) {
         end_len = find_last_bit(cpu->sve_vq_map, start_len);
         assert(end_len < start_len);