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[Qemu-devel] [PATCH 03/11] target-arm: Raw CPSR writes should skip check
From: |
Peter Maydell |
Subject: |
[Qemu-devel] [PATCH 03/11] target-arm: Raw CPSR writes should skip checks and bank switching |
Date: |
Mon, 15 Feb 2016 17:22:49 +0000 |
Raw CPSR writes should skip the architectural checks for whether
we're allowed to set the A or F bits and should also not do
the switching of register banks if the mode changes. Handle
this inside cpsr_write(), which allows us to drop the "manually
set the mode bits to avoid the bank switch" code from all the
callsites which are using CPSRWriteRaw.
This fixes a bug in 32-bit KVM handling where we had forgotten
the "manually set the mode bits" part and could thus potentially
trash the register state if the mode from the last exit to userspace
differed from the mode on this exit.
Signed-off-by: Peter Maydell <address@hidden>
---
target-arm/helper.c | 5 +++--
target-arm/kvm64.c | 1 -
target-arm/machine.c | 2 --
target-arm/op_helper.c | 5 ++++-
4 files changed, 7 insertions(+), 6 deletions(-)
diff --git a/target-arm/helper.c b/target-arm/helper.c
index 828822b..d1919bb 100644
--- a/target-arm/helper.c
+++ b/target-arm/helper.c
@@ -5234,7 +5234,7 @@ void cpsr_write(CPUARMState *env, uint32_t val, uint32_t
mask,
* In a V8 implementation, it is permitted for privileged software to
* change the CPSR A/F bits regardless of the SCR.AW/FW bits.
*/
- if (!arm_feature(env, ARM_FEATURE_V8) &&
+ if (write_type != CPSRWriteRaw && !arm_feature(env, ARM_FEATURE_V8) &&
arm_feature(env, ARM_FEATURE_EL3) &&
!arm_feature(env, ARM_FEATURE_EL2) &&
!arm_is_secure(env)) {
@@ -5281,7 +5281,8 @@ void cpsr_write(CPUARMState *env, uint32_t val, uint32_t
mask,
env->daif &= ~(CPSR_AIF & mask);
env->daif |= val & CPSR_AIF & mask;
- if ((env->uncached_cpsr ^ val) & mask & CPSR_M) {
+ if (write_type != CPSRWriteRaw &&
+ ((env->uncached_cpsr ^ val) & mask & CPSR_M)) {
if (bad_mode_switch(env, val & CPSR_M)) {
/* Attempt to switch to an invalid mode: this is UNPREDICTABLE.
* We choose to ignore the attempt and leave the CPSR M field
diff --git a/target-arm/kvm64.c b/target-arm/kvm64.c
index 08c2c81..e8527bf 100644
--- a/target-arm/kvm64.c
+++ b/target-arm/kvm64.c
@@ -722,7 +722,6 @@ int kvm_arch_get_registers(CPUState *cs)
if (is_a64(env)) {
pstate_write(env, val);
} else {
- env->uncached_cpsr = val & CPSR_M;
cpsr_write(env, val, 0xffffffff, CPSRWriteRaw);
}
diff --git a/target-arm/machine.c b/target-arm/machine.c
index 0fc7df0..03a73d9 100644
--- a/target-arm/machine.c
+++ b/target-arm/machine.c
@@ -173,8 +173,6 @@ static int get_cpsr(QEMUFile *f, void *opaque, size_t size)
return 0;
}
- /* Avoid mode switch when restoring CPSR */
- env->uncached_cpsr = val & CPSR_M;
cpsr_write(env, val, 0xffffffff, CPSRWriteRaw);
return 0;
}
diff --git a/target-arm/op_helper.c b/target-arm/op_helper.c
index 543d33a..4881e34 100644
--- a/target-arm/op_helper.c
+++ b/target-arm/op_helper.c
@@ -779,7 +779,10 @@ void HELPER(exception_return)(CPUARMState *env)
if (!return_to_aa64) {
env->aarch64 = 0;
- env->uncached_cpsr = spsr & CPSR_M;
+ /* We do a raw CPSR write because aarch64_sync_64_to_32()
+ * will sort the register banks out for us, and we've already
+ * caught all the bad-mode cases in el_from_spsr().
+ */
cpsr_write(env, spsr, ~0, CPSRWriteRaw);
if (!arm_singlestep_active(env)) {
env->uncached_cpsr &= ~PSTATE_SS;
--
1.9.1
- [Qemu-devel] [PATCH 07/11] target-arm: Add Hyp mode checks to bad_mode_switch(), (continued)
- [Qemu-devel] [PATCH 07/11] target-arm: Add Hyp mode checks to bad_mode_switch(), Peter Maydell, 2016/02/15
- [Qemu-devel] [PATCH 05/11] target-arm: In cpsr_write() ignore mode switches from User mode, Peter Maydell, 2016/02/15
- [Qemu-devel] [PATCH 01/11] target-arm: Give CPSR setting on 32-bit exception return its own helper, Peter Maydell, 2016/02/15
- [Qemu-devel] [PATCH 06/11] target-arm: Add comment about not implementing NSACR.RFR, Peter Maydell, 2016/02/15
- [Qemu-devel] [PATCH 10/11] target-arm: Make mode switches from Hyp via CPS and MRS illegal, Peter Maydell, 2016/02/15
- [Qemu-devel] [PATCH 03/11] target-arm: Raw CPSR writes should skip checks and bank switching,
Peter Maydell <=