Hello Andreas Sandberg,
I'd like you to do a code review. Please visit
https://gem5-review.googlesource.com/8021
to review the following change.
Change subject: arch-arm: Don't change PSTATE in Illegal Exception return
......................................................................
arch-arm: Don't change PSTATE in Illegal Exception return
This patch fixes the Illegal Exception return handler. According to the
armarm documentation, when PSTATE.IL is set to one because of an illegal
exception return, PSTATE.{EL, nRW, SP} are unchanged. This means the
Exception level, Execution state, and stack pointer selection do not
change as a result of the return.
Change-Id: I35f2fe68fb2822a54fc4a21930871eab7a1aaab4
Signed-off-by: Giacomo Travaglini <[email protected]>
Reviewed-by: Andreas Sandberg <[email protected]>
---
M src/arch/arm/insts/static_inst.cc
M src/arch/arm/isa.cc
2 files changed, 11 insertions(+), 1 deletion(-)
diff --git a/src/arch/arm/insts/static_inst.cc
b/src/arch/arm/insts/static_inst.cc
index aace1de..a7ba91e 100644
--- a/src/arch/arm/insts/static_inst.cc
+++ b/src/arch/arm/insts/static_inst.cc
@@ -1018,7 +1018,17 @@
new_cpsr.ss = 0;
if (illegalExceptionReturn(tc, cpsr, spsr)) {
+ // If the SPSR specifies an illegal exception return,
+ // then PSTATE.{M, nRW, EL, SP} are unchanged and PSTATE.IL
+ // is set to 1.
new_cpsr.il = 1;
+ if (cpsr.width) {
+ new_cpsr.mode = cpsr.mode;
+ } else {
+ new_cpsr.width = cpsr.width;
+ new_cpsr.el = cpsr.el;
+ new_cpsr.sp = cpsr.sp;
+ }
} else {
new_cpsr.il = spsr.il;
if (spsr.width && badMode32((OperatingMode)(uint8_t)spsr.mode)) {
diff --git a/src/arch/arm/isa.cc b/src/arch/arm/isa.cc
index c917aba..51f7129 100644
--- a/src/arch/arm/isa.cc
+++ b/src/arch/arm/isa.cc
@@ -726,7 +726,7 @@
CPSR old_cpsr = miscRegs[MISCREG_CPSR];
int old_mode = old_cpsr.mode;
CPSR cpsr = val;
- if (old_mode != cpsr.mode) {
+ if (old_mode != cpsr.mode || cpsr.il == 1) {
getITBPtr(tc)->invalidateMiscReg();
getDTBPtr(tc)->invalidateMiscReg();
}
--
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Gerrit-Project: public/gem5
Gerrit-Branch: master
Gerrit-MessageType: newchange
Gerrit-Change-Id: I35f2fe68fb2822a54fc4a21930871eab7a1aaab4
Gerrit-Change-Number: 8021
Gerrit-PatchSet: 1
Gerrit-Owner: Giacomo Travaglini <[email protected]>
Gerrit-Reviewer: Andreas Sandberg <[email protected]>
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