From abc24d86cc0364f402e438fae3acb14289b40734 Mon Sep 17 00:00:00 2001 From: Michael Davidsaver Date: Fri, 27 Jan 2017 15:20:21 +0000 Subject: [PATCH] armv7m: Fix reads of CONTROL register bit 1 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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 Reviewed-by: Alex Bennée 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 --- target/arm/cpu.h | 1 - target/arm/helper.c | 35 +++++++++++++++++++++++------------ target/arm/internals.h | 7 +++++++ target/arm/machine.c | 6 ++---- 4 files changed, 32 insertions(+), 17 deletions(-) diff --git a/target/arm/cpu.h b/target/arm/cpu.h index 151a5d754e..521c11b780 100644 --- a/target/arm/cpu.h +++ b/target/arm/cpu.h @@ -405,7 +405,6 @@ typedef struct CPUARMState { uint32_t vecbase; uint32_t basepri; uint32_t control; - int current_sp; int exception; } v7m; 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" diff --git a/target/arm/internals.h b/target/arm/internals.h index 3cae5ff3b5..2e65bc12fa 100644 --- a/target/arm/internals.h +++ b/target/arm/internals.h @@ -25,6 +25,8 @@ #ifndef TARGET_ARM_INTERNALS_H #define TARGET_ARM_INTERNALS_H +#include "hw/registerfields.h" + /* register banks for CPU modes */ #define BANK_USRSYS 0 #define BANK_SVC 1 @@ -75,6 +77,11 @@ static const char * const excnames[] = { */ #define GTIMER_SCALE 16 +/* Bit definitions for the v7M CONTROL register */ +FIELD(V7M_CONTROL, NPRIV, 0, 1) +FIELD(V7M_CONTROL, SPSEL, 1, 1) +FIELD(V7M_CONTROL, FPCA, 2, 1) + /* * For AArch64, map a given EL to an index in the banked_spsr array. * Note that this mapping and the AArch32 mapping defined in bank_number() diff --git a/target/arm/machine.c b/target/arm/machine.c index 487320db1d..8d93571b19 100644 --- a/target/arm/machine.c +++ b/target/arm/machine.c @@ -99,15 +99,13 @@ static bool m_needed(void *opaque) static const VMStateDescription vmstate_m = { .name = "cpu/m", - .version_id = 1, - .minimum_version_id = 1, + .version_id = 2, + .minimum_version_id = 2, .needed = m_needed, .fields = (VMStateField[]) { - VMSTATE_UINT32(env.v7m.other_sp, ARMCPU), VMSTATE_UINT32(env.v7m.vecbase, ARMCPU), VMSTATE_UINT32(env.v7m.basepri, ARMCPU), VMSTATE_UINT32(env.v7m.control, ARMCPU), - VMSTATE_INT32(env.v7m.current_sp, ARMCPU), VMSTATE_INT32(env.v7m.exception, ARMCPU), VMSTATE_END_OF_LIST() }