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Re: [Qemu-arm] [PATCH 5/7] target/arm: Make v7m_push_callee_stack() hono
From: |
Philippe Mathieu-Daudé |
Subject: |
Re: [Qemu-arm] [PATCH 5/7] target/arm: Make v7m_push_callee_stack() honour MPU |
Date: |
Mon, 5 Feb 2018 20:48:34 -0300 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.5.2 |
On 01/30/2018 12:02 PM, Peter Maydell wrote:
> Make v7m_push_callee_stack() honour the MPU by using the
> new v7m_stack_write() function. We return a flag to indicate
> whether the pushes failed, which we can then use in
> v7m_exception_taken() to cause us to handle the derived
> exception correctly.
>
> Signed-off-by: Peter Maydell <address@hidden>
> ---
> target/arm/helper.c | 64
> ++++++++++++++++++++++++++++++++++++++++-------------
> 1 file changed, 49 insertions(+), 15 deletions(-)
>
> diff --git a/target/arm/helper.c b/target/arm/helper.c
> index 007e760..de0031b 100644
> --- a/target/arm/helper.c
> +++ b/target/arm/helper.c
> @@ -6473,7 +6473,7 @@ static uint32_t arm_v7m_load_vector(ARMCPU *cpu, int
> exc, bool targets_secure)
> return addr;
> }
>
> -static void v7m_push_callee_stack(ARMCPU *cpu, uint32_t lr, bool dotailchain,
> +static bool v7m_push_callee_stack(ARMCPU *cpu, uint32_t lr, bool dotailchain,
> bool ignore_faults)
> {
> /* For v8M, push the callee-saves register part of the stack frame.
> @@ -6481,31 +6481,55 @@ static void v7m_push_callee_stack(ARMCPU *cpu,
> uint32_t lr, bool dotailchain,
> * In the tailchaining case this may not be the current stack.
> */
> CPUARMState *env = &cpu->env;
> - CPUState *cs = CPU(cpu);
> uint32_t *frame_sp_p;
> uint32_t frameptr;
> + ARMMMUIdx mmu_idx;
> + bool stacked_ok;
>
> if (dotailchain) {
> - frame_sp_p = get_v7m_sp_ptr(env, true,
> - lr & R_V7M_EXCRET_MODE_MASK,
> + bool mode = lr & R_V7M_EXCRET_MODE_MASK;
> + bool priv = !(env->v7m.control[M_REG_S] & R_V7M_CONTROL_NPRIV_MASK)
> ||
> + !mode;
> +
> + mmu_idx = arm_v7m_mmu_idx_for_secstate_and_priv(env, M_REG_S, priv);
> + frame_sp_p = get_v7m_sp_ptr(env, M_REG_S, mode,
> lr & R_V7M_EXCRET_SPSEL_MASK);
> } else {
> + mmu_idx = core_to_arm_mmu_idx(env, cpu_mmu_index(env, false));
> frame_sp_p = &env->regs[13];
> }
>
> frameptr = *frame_sp_p - 0x28;
>
> - stl_phys(cs->as, frameptr, 0xfefa125b);
> - stl_phys(cs->as, frameptr + 0x8, env->regs[4]);
> - stl_phys(cs->as, frameptr + 0xc, env->regs[5]);
> - stl_phys(cs->as, frameptr + 0x10, env->regs[6]);
> - stl_phys(cs->as, frameptr + 0x14, env->regs[7]);
> - stl_phys(cs->as, frameptr + 0x18, env->regs[8]);
> - stl_phys(cs->as, frameptr + 0x1c, env->regs[9]);
> - stl_phys(cs->as, frameptr + 0x20, env->regs[10]);
> - stl_phys(cs->as, frameptr + 0x24, env->regs[11]);
> + /* Write as much of the stack frame as we can. A write failure may
> + * cause us to pend a derived exception.
> + */
> + stacked_ok =
> + v7m_stack_write(cpu, frameptr, 0xfefa125b, mmu_idx, ignore_faults) &&
> + v7m_stack_write(cpu, frameptr + 0x8, env->regs[4], mmu_idx,
nice!
Reviewed-by: Philippe Mathieu-Daudé <address@hidden>
> + ignore_faults) &&
> + v7m_stack_write(cpu, frameptr + 0xc, env->regs[5], mmu_idx,
> + ignore_faults) &&
> + v7m_stack_write(cpu, frameptr + 0x10, env->regs[6], mmu_idx,
> + ignore_faults) &&
> + v7m_stack_write(cpu, frameptr + 0x14, env->regs[7], mmu_idx,
> + ignore_faults) &&
> + v7m_stack_write(cpu, frameptr + 0x18, env->regs[8], mmu_idx,
> + ignore_faults) &&
> + v7m_stack_write(cpu, frameptr + 0x1c, env->regs[9], mmu_idx,
> + ignore_faults) &&
> + v7m_stack_write(cpu, frameptr + 0x20, env->regs[10], mmu_idx,
> + ignore_faults) &&
> + v7m_stack_write(cpu, frameptr + 0x24, env->regs[11], mmu_idx,
> + ignore_faults);
>
> + /* Update SP regardless of whether any of the stack accesses failed.
> + * When we implement v8M stack limit checking then this attempt to
> + * update SP might also fail and result in a derived exception.
> + */
> *frame_sp_p = frameptr;
> +
> + return !stacked_ok;
> }
>
> static void v7m_exception_taken(ARMCPU *cpu, uint32_t lr, bool dotailchain,
> @@ -6519,6 +6543,7 @@ static void v7m_exception_taken(ARMCPU *cpu, uint32_t
> lr, bool dotailchain,
> uint32_t addr;
> bool targets_secure;
> int exc;
> + bool push_failed = false;
>
> armv7m_nvic_get_pending_irq_info(env->nvic, &exc, &targets_secure);
>
> @@ -6546,8 +6571,8 @@ static void v7m_exception_taken(ARMCPU *cpu, uint32_t
> lr, bool dotailchain,
> */
> if (lr & R_V7M_EXCRET_DCRS_MASK &&
> !(dotailchain && (lr & R_V7M_EXCRET_ES_MASK))) {
> - v7m_push_callee_stack(cpu, lr, dotailchain,
> - ignore_stackfaults);
> + push_failed = v7m_push_callee_stack(cpu, lr, dotailchain,
> + ignore_stackfaults);
> }
> lr |= R_V7M_EXCRET_DCRS_MASK;
> }
> @@ -6589,6 +6614,15 @@ static void v7m_exception_taken(ARMCPU *cpu, uint32_t
> lr, bool dotailchain,
> }
> }
>
> + if (push_failed && !ignore_stackfaults) {
> + /* Derived exception on callee-saves register stacking:
> + * we might now want to take a different exception which
> + * targets a different security state, so try again from the top.
> + */
> + v7m_exception_taken(cpu, lr, true, true);
> + return;
> + }
> +
> addr = arm_v7m_load_vector(cpu, exc, targets_secure);
>
> /* Now we've done everything that might cause a derived exception
>
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Philippe Mathieu-Daudé <=