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[PATCH v4 2/4] target/arm: Support AA32 DIT by moving PSTATE_SS from cps
From: |
Rebecca Cran |
Subject: |
[PATCH v4 2/4] target/arm: Support AA32 DIT by moving PSTATE_SS from cpsr into env->pstate |
Date: |
Tue, 2 Feb 2021 21:58:14 -0700 |
cpsr has been treated as being the same as spsr, but it isn't.
Since PSTATE_SS isn't in cpsr, remove it and move it into env->pstate.
This allows us to add support for CPSR_DIT, adding helper functions
to merge SPSR_ELx to and from CPSR.
Signed-off-by: Rebecca Cran <rebecca@nuviainc.com>
---
target/arm/helper-a64.c | 32 +++++++++++++++++---
target/arm/helper.c | 27 ++++++++++++-----
target/arm/op_helper.c | 9 +-----
3 files changed, 49 insertions(+), 19 deletions(-)
diff --git a/target/arm/helper-a64.c b/target/arm/helper-a64.c
index c426c23d2c4e..be5d3f6e75cb 100644
--- a/target/arm/helper-a64.c
+++ b/target/arm/helper-a64.c
@@ -945,11 +945,31 @@ static int el_from_spsr(uint32_t spsr)
}
}
+static void cpsr_write_from_spsr_elx(CPUARMState *env,
+ uint32_t val)
+{
+ uint32_t mask;
+
+ /* Save SPSR_ELx.SS into PSTATE. */
+ env->pstate = (env->pstate & ~PSTATE_SS) | (val & PSTATE_SS);
+ val &= ~PSTATE_SS;
+
+ /* Move DIT to the correct location for CPSR */
+ if (val & PSTATE_DIT) {
+ val &= ~PSTATE_DIT;
+ val |= CPSR_DIT;
+ }
+
+ mask = aarch32_cpsr_valid_mask(env->features, \
+ &env_archcpu(env)->isar);
+ cpsr_write(env, val, mask, CPSRWriteRaw);
+}
+
void HELPER(exception_return)(CPUARMState *env, uint64_t new_pc)
{
int cur_el = arm_current_el(env);
unsigned int spsr_idx = aarch64_banked_spsr_index(cur_el);
- uint32_t mask, spsr = env->banked_spsr[spsr_idx];
+ uint32_t spsr = env->banked_spsr[spsr_idx];
int new_el;
bool return_to_aa64 = (spsr & PSTATE_nRW) == 0;
@@ -998,11 +1018,13 @@ void HELPER(exception_return)(CPUARMState *env, uint64_t
new_pc)
* will sort the register banks out for us, and we've already
* caught all the bad-mode cases in el_from_spsr().
*/
- mask = aarch32_cpsr_valid_mask(env->features, &env_archcpu(env)->isar);
- cpsr_write(env, spsr, mask, CPSRWriteRaw);
+ cpsr_write_from_spsr_elx(env, spsr);
if (!arm_singlestep_active(env)) {
- env->uncached_cpsr &= ~PSTATE_SS;
+ env->pstate &= ~PSTATE_SS;
+ } else {
+ env->pstate |= PSTATE_SS;
}
+
aarch64_sync_64_to_32(env);
if (spsr & CPSR_T) {
@@ -1022,6 +1044,8 @@ void HELPER(exception_return)(CPUARMState *env, uint64_t
new_pc)
pstate_write(env, spsr);
if (!arm_singlestep_active(env)) {
env->pstate &= ~PSTATE_SS;
+ } else {
+ env->pstate |= PSTATE_SS;
}
aarch64_restore_sp(env, new_el);
helper_rebuild_hflags_a64(env, new_el);
diff --git a/target/arm/helper.c b/target/arm/helper.c
index 0aad6d79dcb1..a31f37e2a257 100644
--- a/target/arm/helper.c
+++ b/target/arm/helper.c
@@ -9420,6 +9420,21 @@ void aarch64_sync_64_to_32(CPUARMState *env)
env->regs[15] = env->pc;
}
+static uint32_t cpsr_read_for_spsr_elx(CPUARMState *env)
+{
+ uint32_t ret = cpsr_read(env);
+
+ /* Move DIT to the correct location for SPSR_ELx */
+ if (ret & CPSR_DIT) {
+ ret &= ~CPSR_DIT;
+ ret |= PSTATE_DIT;
+ }
+ /* Merge PSTATE.SS into SPSR_ELx */
+ ret |= env->pstate & PSTATE_SS;
+
+ return ret;
+}
+
static void take_aarch32_exception(CPUARMState *env, int new_mode,
uint32_t mask, uint32_t offset,
uint32_t newpc)
@@ -9433,8 +9448,9 @@ static void take_aarch32_exception(CPUARMState *env, int
new_mode,
* For exceptions taken to AArch32 we must clear the SS bit in both
* PSTATE and in the old-state value we save to SPSR_<mode>, so zero it
now.
*/
- env->uncached_cpsr &= ~PSTATE_SS;
- env->spsr = cpsr_read(env);
+ env->pstate &= ~PSTATE_SS;
+ env->spsr = cpsr_read_for_spsr_elx(env);
+
/* Clear IT bits. */
env->condexec_bits = 0;
/* Switch to the new mode, and to the correct instruction set. */
@@ -9911,7 +9927,7 @@ static void arm_cpu_do_interrupt_aarch64(CPUState *cs)
aarch64_save_sp(env, arm_current_el(env));
env->elr_el[new_el] = env->pc;
} else {
- old_mode = cpsr_read(env);
+ old_mode = cpsr_read_for_spsr_elx(env);
env->elr_el[new_el] = env->regs[15];
aarch64_sync_32_to_64(env);
@@ -13201,7 +13217,6 @@ void cpu_get_tb_cpu_state(CPUARMState *env,
target_ulong *pc,
target_ulong *cs_base, uint32_t *pflags)
{
uint32_t flags = env->hflags;
- uint32_t pstate_for_ss;
*cs_base = 0;
assert_hflags_rebuild_correctly(env);
@@ -13211,7 +13226,6 @@ void cpu_get_tb_cpu_state(CPUARMState *env,
target_ulong *pc,
if (cpu_isar_feature(aa64_bti, env_archcpu(env))) {
flags = FIELD_DP32(flags, TBFLAG_A64, BTYPE, env->btype);
}
- pstate_for_ss = env->pstate;
} else {
*pc = env->regs[15];
@@ -13259,7 +13273,6 @@ void cpu_get_tb_cpu_state(CPUARMState *env,
target_ulong *pc,
flags = FIELD_DP32(flags, TBFLAG_AM32, THUMB, env->thumb);
flags = FIELD_DP32(flags, TBFLAG_AM32, CONDEXEC, env->condexec_bits);
- pstate_for_ss = env->uncached_cpsr;
}
/*
@@ -13272,7 +13285,7 @@ void cpu_get_tb_cpu_state(CPUARMState *env,
target_ulong *pc,
* SS_ACTIVE is set in hflags; PSTATE_SS is computed every TB.
*/
if (FIELD_EX32(flags, TBFLAG_ANY, SS_ACTIVE) &&
- (pstate_for_ss & PSTATE_SS)) {
+ (env->pstate & PSTATE_SS)) {
flags = FIELD_DP32(flags, TBFLAG_ANY, PSTATE_SS, 1);
}
diff --git a/target/arm/op_helper.c b/target/arm/op_helper.c
index 5e0f123043b5..65cb37d088f8 100644
--- a/target/arm/op_helper.c
+++ b/target/arm/op_helper.c
@@ -389,14 +389,7 @@ void HELPER(exception_bkpt_insn)(CPUARMState *env,
uint32_t syndrome)
uint32_t HELPER(cpsr_read)(CPUARMState *env)
{
- /*
- * We store the ARMv8 PSTATE.SS bit in env->uncached_cpsr.
- * This is convenient for populating SPSR_ELx, but must be
- * hidden from aarch32 mode, where it is not visible.
- *
- * TODO: ARMv8.4-DIT -- need to move SS somewhere else.
- */
- return cpsr_read(env) & ~(CPSR_EXEC | PSTATE_SS);
+ return cpsr_read(env) & ~CPSR_EXEC;
}
void HELPER(cpsr_write)(CPUARMState *env, uint32_t val, uint32_t mask)
--
2.26.2