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| author | Peter Maydell <peter.maydell@linaro.org> | 2021-07-30 16:16:36 +0100 |
|---|---|---|
| committer | Peter Maydell <peter.maydell@linaro.org> | 2021-08-25 10:48:50 +0100 |
| commit | e5346292966f5348cd36668f2451ca0e44d820b2 (patch) | |
| tree | 8edd319248d5af1846e528cc6c98f0342a00cdf3 /target/arm/helper.c | |
| parent | fc7a5038a6b70a3e474e58a5ed9845e4f5eed6dd (diff) | |
| download | focaccia-qemu-e5346292966f5348cd36668f2451ca0e44d820b2.tar.gz focaccia-qemu-e5346292966f5348cd36668f2451ca0e44d820b2.zip | |
target/arm: Implement M-profile trapping on division by zero
Unlike A-profile, for M-profile the UDIV and SDIV insns can be configured to raise an exception on division by zero, using the CCR DIV_0_TRP bit. Implement support for setting this bit by making the helper functions raise the appropriate exception. Signed-off-by: Peter Maydell <peter.maydell@linaro.org> Reviewed-by: Richard Henderson <richard.henderson@linaro.org> Message-id: 20210730151636.17254-3-peter.maydell@linaro.org
Diffstat (limited to 'target/arm/helper.c')
| -rw-r--r-- | target/arm/helper.c | 19 |
1 files changed, 17 insertions, 2 deletions
diff --git a/target/arm/helper.c b/target/arm/helper.c index 8e9c2a2cf8..56c520cf8e 100644 --- a/target/arm/helper.c +++ b/target/arm/helper.c @@ -9345,6 +9345,18 @@ uint32_t HELPER(sxtb16)(uint32_t x) return res; } +static void handle_possible_div0_trap(CPUARMState *env, uintptr_t ra) +{ + /* + * Take a division-by-zero exception if necessary; otherwise return + * to get the usual non-trapping division behaviour (result of 0) + */ + if (arm_feature(env, ARM_FEATURE_M) + && (env->v7m.ccr[env->v7m.secure] & R_V7M_CCR_DIV_0_TRP_MASK)) { + raise_exception_ra(env, EXCP_DIVBYZERO, 0, 1, ra); + } +} + uint32_t HELPER(uxtb16)(uint32_t x) { uint32_t res; @@ -9353,9 +9365,10 @@ uint32_t HELPER(uxtb16)(uint32_t x) return res; } -int32_t HELPER(sdiv)(int32_t num, int32_t den) +int32_t HELPER(sdiv)(CPUARMState *env, int32_t num, int32_t den) { if (den == 0) { + handle_possible_div0_trap(env, GETPC()); return 0; } if (num == INT_MIN && den == -1) { @@ -9364,9 +9377,10 @@ int32_t HELPER(sdiv)(int32_t num, int32_t den) return num / den; } -uint32_t HELPER(udiv)(uint32_t num, uint32_t den) +uint32_t HELPER(udiv)(CPUARMState *env, uint32_t num, uint32_t den) { if (den == 0) { + handle_possible_div0_trap(env, GETPC()); return 0; } return num / den; @@ -9567,6 +9581,7 @@ void arm_log_exception(int idx) [EXCP_LAZYFP] = "v7M exception during lazy FP stacking", [EXCP_LSERR] = "v8M LSERR UsageFault", [EXCP_UNALIGNED] = "v7M UNALIGNED UsageFault", + [EXCP_DIVBYZERO] = "v7M DIVBYZERO UsageFault", }; if (idx >= 0 && idx < ARRAY_SIZE(excnames)) { |