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From: Peter Maydell <peter.maydell@linaro.org>
To: qemu-devel@nongnu.org
Date: Mon, 29 Apr 2019 18:00:05 +0100
Message-Id: <20190429170030.11323-18-peter.maydell@linaro.org>
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Subject: [Qemu-devel] [PULL 17/42] target/arm: Allow for floating point in
callee stack integrity check
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The magic value pushed onto the callee stack as an integrity
check is different if floating point is present.
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20190416125744.27770-15-peter.maydell@linaro.org
---
target/arm/helper.c | 22 +++++++++++++++++++---
1 file changed, 19 insertions(+), 3 deletions(-)
diff --git a/target/arm/helper.c b/target/arm/helper.c
index da0b6202400..c7b1a8d231d 100644
--- a/target/arm/helper.c
+++ b/target/arm/helper.c
@@ -7979,6 +7979,21 @@ load_fail:
return false;
}
=20
+static uint32_t v7m_integrity_sig(CPUARMState *env, uint32_t lr)
+{
+ /*
+ * Return the integrity signature value for the callee-saves
+ * stack frame section. @lr is the exception return payload/LR value
+ * whose FType bit forms bit 0 of the signature if FP is present.
+ */
+ uint32_t sig =3D 0xfefa125a;
+
+ if (!arm_feature(env, ARM_FEATURE_VFP) || (lr & R_V7M_EXCRET_FTYPE_MAS=
K)) {
+ sig |=3D 1;
+ }
+ return sig;
+}
+
static bool v7m_push_callee_stack(ARMCPU *cpu, uint32_t lr, bool dotailcha=
in,
bool ignore_faults)
{
@@ -7993,6 +8008,7 @@ static bool v7m_push_callee_stack(ARMCPU *cpu, uint32=
_t lr, bool dotailchain,
bool stacked_ok;
uint32_t limit;
bool want_psp;
+ uint32_t sig;
=20
if (dotailchain) {
bool mode =3D lr & R_V7M_EXCRET_MODE_MASK;
@@ -8034,8 +8050,9 @@ static bool v7m_push_callee_stack(ARMCPU *cpu, uint32=
_t lr, bool dotailchain,
/* Write as much of the stack frame as we can. A write failure may
* cause us to pend a derived exception.
*/
+ sig =3D v7m_integrity_sig(env, lr);
stacked_ok =3D
- v7m_stack_write(cpu, frameptr, 0xfefa125b, mmu_idx, ignore_faults)=
&&
+ v7m_stack_write(cpu, frameptr, sig, mmu_idx, ignore_faults) &&
v7m_stack_write(cpu, frameptr + 0x8, env->regs[4], mmu_idx,
ignore_faults) &&
v7m_stack_write(cpu, frameptr + 0xc, env->regs[5], mmu_idx,
@@ -8640,12 +8657,11 @@ static void do_v7m_exception_exit(ARMCPU *cpu)
if (return_to_secure &&
((excret & R_V7M_EXCRET_ES_MASK) =3D=3D 0 ||
(excret & R_V7M_EXCRET_DCRS_MASK) =3D=3D 0)) {
- uint32_t expected_sig =3D 0xfefa125b;
uint32_t actual_sig;
=20
pop_ok =3D v7m_stack_read(cpu, &actual_sig, frameptr, mmu_idx);
=20
- if (pop_ok && expected_sig !=3D actual_sig) {
+ if (pop_ok && v7m_integrity_sig(env, excret) !=3D actual_sig) {
/* Take a SecureFault on the current stack */
env->v7m.sfsr |=3D R_V7M_SFSR_INVIS_MASK;
armv7m_nvic_set_pending(env->nvic, ARMV7M_EXCP_SECURE, fal=
se);
--=20
2.20.1