| Message ID | 1485285380-10565-11-git-send-email-peter.maydell@linaro.org |
|---|---|
| State | New |
| Headers | show |
Peter Maydell <peter.maydell@linaro.org> writes: > For M profile (unlike A profile) the reset value of R14 is specified > as 0xffffffff. (The rationale is that this is an illegal exception > return value, so if guest code tries to return to it it will result > in a helpful exception.) > > Registers r0 to r12 and the flags are architecturally UNKNOWN on > reset, so we leave those at zero. > > Signed-off-by: Peter Maydell <peter.maydell@linaro.org> Reviewed-by: Alex Bennée <alex.bennee@linaro.org> > --- > target/arm/cpu.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/target/arm/cpu.c b/target/arm/cpu.c > index 0814f73..e9f10f7 100644 > --- a/target/arm/cpu.c > +++ b/target/arm/cpu.c > @@ -196,6 +196,9 @@ static void arm_cpu_reset(CPUState *s) > */ > env->v7m.ccr = R_V7M_CCR_STKALIGN_MASK; > > + /* Unlike A/R profile, M profile defines the reset LR value */ > + env->regs[14] = 0xffffffff; > + > /* Load the initial SP and PC from the vector table at address 0 */ > rom = rom_ptr(0); > if (rom) { -- Alex Bennée
diff --git a/target/arm/cpu.c b/target/arm/cpu.c index 0814f73..e9f10f7 100644 --- a/target/arm/cpu.c +++ b/target/arm/cpu.c @@ -196,6 +196,9 @@ static void arm_cpu_reset(CPUState *s) */ env->v7m.ccr = R_V7M_CCR_STKALIGN_MASK; + /* Unlike A/R profile, M profile defines the reset LR value */ + env->regs[14] = 0xffffffff; + /* Load the initial SP and PC from the vector table at address 0 */ rom = rom_ptr(0); if (rom) {
For M profile (unlike A profile) the reset value of R14 is specified as 0xffffffff. (The rationale is that this is an illegal exception return value, so if guest code tries to return to it it will result in a helpful exception.) Registers r0 to r12 and the flags are architecturally UNKNOWN on reset, so we leave those at zero. Signed-off-by: Peter Maydell <peter.maydell@linaro.org> --- target/arm/cpu.c | 3 +++ 1 file changed, 3 insertions(+)