diff options
author | Michael Davidsaver <mdavidsaver@gmail.com> | 2017-01-27 15:20:21 +0000 |
---|---|---|
committer | Peter Maydell <peter.maydell@linaro.org> | 2017-01-27 15:20:21 +0000 |
commit | abc24d86cc0364f402e438fae3acb14289b40734 (patch) | |
tree | 911dbdb831c2f2b1da74b3900f7665bf02fd8f71 /target/arm/helper.c | |
parent | afb3141c660f3dca38227901c5c62cef7af86647 (diff) |
armv7m: Fix reads of CONTROL register bit 1
The v7m CONTROL register bit 1 is SPSEL, which indicates
the stack being used. We were storing this information
not in v7m.control but in the separate v7m.other_sp
structure field. Unfortunately, the code handling reads
of the CONTROL register didn't take account of this, and
so if SPSEL was updated by an exception entry or exit then
a subsequent guest read of CONTROL would get the wrong value.
Using a separate structure field doesn't really gain us
anything in efficiency, so drop this unnecessary complexity
in favour of simply storing all the bits in v7m.control.
This is a migration compatibility break for M profile
CPUs only.
Signed-off-by: Michael Davidsaver <mdavidsaver@gmail.com>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Message-id: 1484937883-1068-6-git-send-email-peter.maydell@linaro.org
[PMM: rewrote commit message;
use deposit32(); use FIELD to define constants for
masking and shifting of CONTROL register fields
]
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Diffstat (limited to 'target/arm/helper.c')
-rw-r--r-- | target/arm/helper.c | 35 |
1 files changed, 23 insertions, 12 deletions
diff --git a/target/arm/helper.c b/target/arm/helper.c index 8edb08cbc1..dc383d16bb 100644 --- a/target/arm/helper.c +++ b/target/arm/helper.c @@ -5947,14 +5947,19 @@ static uint32_t v7m_pop(CPUARMState *env) } /* Switch to V7M main or process stack pointer. */ -static void switch_v7m_sp(CPUARMState *env, int process) +static void switch_v7m_sp(CPUARMState *env, bool new_spsel) { uint32_t tmp; - if (env->v7m.current_sp != process) { + bool old_spsel = env->v7m.control & R_V7M_CONTROL_SPSEL_MASK; + + if (old_spsel != new_spsel) { tmp = env->v7m.other_sp; env->v7m.other_sp = env->regs[13]; env->regs[13] = tmp; - env->v7m.current_sp = process; + + env->v7m.control = deposit32(env->v7m.control, + R_V7M_CONTROL_SPSEL_SHIFT, + R_V7M_CONTROL_SPSEL_LENGTH, new_spsel); } } @@ -6049,8 +6054,9 @@ void arm_v7m_cpu_do_interrupt(CPUState *cs) arm_log_exception(cs->exception_index); lr = 0xfffffff1; - if (env->v7m.current_sp) + if (env->v7m.control & R_V7M_CONTROL_SPSEL_MASK) { lr |= 4; + } if (env->v7m.exception == 0) lr |= 8; @@ -8294,9 +8300,11 @@ uint32_t HELPER(v7m_mrs)(CPUARMState *env, uint32_t reg) switch (reg) { case 8: /* MSP */ - return env->v7m.current_sp ? env->v7m.other_sp : env->regs[13]; + return (env->v7m.control & R_V7M_CONTROL_SPSEL_MASK) ? + env->v7m.other_sp : env->regs[13]; case 9: /* PSP */ - return env->v7m.current_sp ? env->regs[13] : env->v7m.other_sp; + return (env->v7m.control & R_V7M_CONTROL_SPSEL_MASK) ? + env->regs[13] : env->v7m.other_sp; case 16: /* PRIMASK */ return (env->daif & PSTATE_I) != 0; case 17: /* BASEPRI */ @@ -8326,16 +8334,18 @@ void HELPER(v7m_msr)(CPUARMState *env, uint32_t reg, uint32_t val) } break; case 8: /* MSP */ - if (env->v7m.current_sp) + if (env->v7m.control & R_V7M_CONTROL_SPSEL_MASK) { env->v7m.other_sp = val; - else + } else { env->regs[13] = val; + } break; case 9: /* PSP */ - if (env->v7m.current_sp) + if (env->v7m.control & R_V7M_CONTROL_SPSEL_MASK) { env->regs[13] = val; - else + } else { env->v7m.other_sp = val; + } break; case 16: /* PRIMASK */ if (val & 1) { @@ -8360,8 +8370,9 @@ void HELPER(v7m_msr)(CPUARMState *env, uint32_t reg, uint32_t val) } break; case 20: /* CONTROL */ - env->v7m.control = val & 3; - switch_v7m_sp(env, (val & 2) != 0); + switch_v7m_sp(env, (val & R_V7M_CONTROL_SPSEL_MASK) != 0); + env->v7m.control = val & (R_V7M_CONTROL_SPSEL_MASK | + R_V7M_CONTROL_NPRIV_MASK); break; default: qemu_log_mask(LOG_GUEST_ERROR, "Attempt to write unknown special" |