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authorRichard Henderson <richard.henderson@linaro.org>2018-03-09 17:09:43 +0000
committerPeter Maydell <peter.maydell@linaro.org>2018-03-09 17:09:43 +0000
commit85fc716732bc6e85a634335847999f411269f282 (patch)
tree15ae6a9a0e2d85baa27d03c67af20b749fd9be6c
parent843361ed04017da5f15c3b7a98b2e8849e39a984 (diff)
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linux-user: Implement aarch64 PR_SVE_SET/GET_VL
As an implementation choice, widening VL has zeroed the previously inaccessible portion of the sve registers. Reviewed-by: Peter Maydell <peter.maydell@linaro.org> Signed-off-by: Richard Henderson <richard.henderson@linaro.org> Acked-by: Alex Bennée <alex.bennee@linaro.org> Message-id: 20180303143823.27055-2-richard.henderson@linaro.org Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
-rw-r--r--linux-user/aarch64/target_syscall.h3
-rw-r--r--linux-user/syscall.c27
-rw-r--r--target/arm/cpu.h1
-rw-r--r--target/arm/cpu64.c41
4 files changed, 72 insertions, 0 deletions
diff --git a/linux-user/aarch64/target_syscall.h b/linux-user/aarch64/target_syscall.h
index 604ab99..205265e 100644
--- a/linux-user/aarch64/target_syscall.h
+++ b/linux-user/aarch64/target_syscall.h
@@ -19,4 +19,7 @@ struct target_pt_regs {
#define TARGET_MLOCKALL_MCL_CURRENT 1
#define TARGET_MLOCKALL_MCL_FUTURE 2
+#define TARGET_PR_SVE_SET_VL 50
+#define TARGET_PR_SVE_GET_VL 51
+
#endif /* AARCH64_TARGET_SYSCALL_H */
diff --git a/linux-user/syscall.c b/linux-user/syscall.c
index a8abfd4..b4f7b14 100644
--- a/linux-user/syscall.c
+++ b/linux-user/syscall.c
@@ -10672,6 +10672,33 @@ abi_long do_syscall(void *cpu_env, int num, abi_long arg1,
break;
}
#endif
+#ifdef TARGET_AARCH64
+ case TARGET_PR_SVE_SET_VL:
+ /* We cannot support either PR_SVE_SET_VL_ONEXEC
+ or PR_SVE_VL_INHERIT. Therefore, anything above
+ ARM_MAX_VQ results in EINVAL. */
+ ret = -TARGET_EINVAL;
+ if (arm_feature(cpu_env, ARM_FEATURE_SVE)
+ && arg2 >= 0 && arg2 <= ARM_MAX_VQ * 16 && !(arg2 & 15)) {
+ CPUARMState *env = cpu_env;
+ int old_vq = (env->vfp.zcr_el[1] & 0xf) + 1;
+ int vq = MAX(arg2 / 16, 1);
+
+ if (vq < old_vq) {
+ aarch64_sve_narrow_vq(env, vq);
+ }
+ env->vfp.zcr_el[1] = vq - 1;
+ ret = vq * 16;
+ }
+ break;
+ case TARGET_PR_SVE_GET_VL:
+ ret = -TARGET_EINVAL;
+ if (arm_feature(cpu_env, ARM_FEATURE_SVE)) {
+ CPUARMState *env = cpu_env;
+ ret = ((env->vfp.zcr_el[1] & 0xf) + 1) * 16;
+ }
+ break;
+#endif /* AARCH64 */
case PR_GET_SECCOMP:
case PR_SET_SECCOMP:
/* Disable seccomp to prevent the target disabling syscalls we
diff --git a/target/arm/cpu.h b/target/arm/cpu.h
index 3fa8fda..36711cd 100644
--- a/target/arm/cpu.h
+++ b/target/arm/cpu.h
@@ -866,6 +866,7 @@ int arm_cpu_write_elf32_note(WriteCoreDumpFunction f, CPUState *cs,
#ifdef TARGET_AARCH64
int aarch64_cpu_gdb_read_register(CPUState *cpu, uint8_t *buf, int reg);
int aarch64_cpu_gdb_write_register(CPUState *cpu, uint8_t *buf, int reg);
+void aarch64_sve_narrow_vq(CPUARMState *env, unsigned vq);
#endif
target_ulong do_arm_semihosting(CPUARMState *env);
diff --git a/target/arm/cpu64.c b/target/arm/cpu64.c
index dd9ba97..f12a485 100644
--- a/target/arm/cpu64.c
+++ b/target/arm/cpu64.c
@@ -368,3 +368,44 @@ static void aarch64_cpu_register_types(void)
}
type_init(aarch64_cpu_register_types)
+
+/* The manual says that when SVE is enabled and VQ is widened the
+ * implementation is allowed to zero the previously inaccessible
+ * portion of the registers. The corollary to that is that when
+ * SVE is enabled and VQ is narrowed we are also allowed to zero
+ * the now inaccessible portion of the registers.
+ *
+ * The intent of this is that no predicate bit beyond VQ is ever set.
+ * Which means that some operations on predicate registers themselves
+ * may operate on full uint64_t or even unrolled across the maximum
+ * uint64_t[4]. Performing 4 bits of host arithmetic unconditionally
+ * may well be cheaper than conditionals to restrict the operation
+ * to the relevant portion of a uint16_t[16].
+ *
+ * TODO: Need to call this for changes to the real system registers
+ * and EL state changes.
+ */
+void aarch64_sve_narrow_vq(CPUARMState *env, unsigned vq)
+{
+ int i, j;
+ uint64_t pmask;
+
+ assert(vq >= 1 && vq <= ARM_MAX_VQ);
+
+ /* Zap the high bits of the zregs. */
+ for (i = 0; i < 32; i++) {
+ memset(&env->vfp.zregs[i].d[2 * vq], 0, 16 * (ARM_MAX_VQ - vq));
+ }
+
+ /* Zap the high bits of the pregs and ffr. */
+ pmask = 0;
+ if (vq & 3) {
+ pmask = ~(-1ULL << (16 * (vq & 3)));
+ }
+ for (j = vq / 4; j < ARM_MAX_VQ / 4; j++) {
+ for (i = 0; i < 17; ++i) {
+ env->vfp.pregs[i].p[j] &= pmask;
+ }
+ pmask = 0;
+ }
+}