diff options
Diffstat (limited to 'target')
| -rw-r--r-- | target/arm/helper.c | 130 |
1 files changed, 98 insertions, 32 deletions
diff --git a/target/arm/helper.c b/target/arm/helper.c index 0b9c9fded6..7548d4c6ec 100644 --- a/target/arm/helper.c +++ b/target/arm/helper.c @@ -6047,16 +6047,6 @@ static void v7m_push(CPUARMState *env, uint32_t val) stl_phys(cs->as, env->regs[13], val); } -static uint32_t v7m_pop(CPUARMState *env) -{ - CPUState *cs = CPU(arm_env_get_cpu(env)); - uint32_t val; - - val = ldl_phys(cs->as, env->regs[13]); - env->regs[13] += 4; - return val; -} - /* Return true if we're using the process stack pointer (not the MSP) */ static bool v7m_using_psp(CPUARMState *env) { @@ -6148,6 +6138,43 @@ void HELPER(v7m_bxns)(CPUARMState *env, uint32_t dest) env->regs[15] = dest & ~1; } +static uint32_t *get_v7m_sp_ptr(CPUARMState *env, bool secure, bool threadmode, + bool spsel) +{ + /* Return a pointer to the location where we currently store the + * stack pointer for the requested security state and thread mode. + * This pointer will become invalid if the CPU state is updated + * such that the stack pointers are switched around (eg changing + * the SPSEL control bit). + * Compare the v8M ARM ARM pseudocode LookUpSP_with_security_mode(). + * Unlike that pseudocode, we require the caller to pass us in the + * SPSEL control bit value; this is because we also use this + * function in handling of pushing of the callee-saves registers + * part of the v8M stack frame (pseudocode PushCalleeStack()), + * and in the tailchain codepath the SPSEL bit comes from the exception + * return magic LR value from the previous exception. The pseudocode + * opencodes the stack-selection in PushCalleeStack(), but we prefer + * to make this utility function generic enough to do the job. + */ + bool want_psp = threadmode && spsel; + + if (secure == env->v7m.secure) { + /* Currently switch_v7m_sp switches SP as it updates SPSEL, + * so the SP we want is always in regs[13]. + * When we decouple SPSEL from the actually selected SP + * we need to check want_psp against v7m_using_psp() + * to see whether we need regs[13] or v7m.other_sp. + */ + return &env->regs[13]; + } else { + if (want_psp) { + return &env->v7m.other_ss_psp; + } else { + return &env->v7m.other_ss_msp; + } + } +} + static uint32_t arm_v7m_load_vector(ARMCPU *cpu) { CPUState *cs = CPU(cpu); @@ -6219,6 +6246,7 @@ static void v7m_push_stack(ARMCPU *cpu) static void do_v7m_exception_exit(ARMCPU *cpu) { CPUARMState *env = &cpu->env; + CPUState *cs = CPU(cpu); uint32_t excret; uint32_t xpsr; bool ufault = false; @@ -6226,6 +6254,7 @@ static void do_v7m_exception_exit(ARMCPU *cpu) bool return_to_handler = false; bool rettobase = false; bool exc_secure = false; + bool return_to_secure; /* We can only get here from an EXCP_EXCEPTION_EXIT, and * gen_bx_excret() enforces the architectural rule @@ -6293,6 +6322,9 @@ static void do_v7m_exception_exit(ARMCPU *cpu) g_assert_not_reached(); } + return_to_secure = arm_feature(env, ARM_FEATURE_M_SECURITY) && + (excret & R_V7M_EXCRET_S_MASK); + switch (excret & 0xf) { case 1: /* Return to Handler */ return_to_handler = true; @@ -6322,32 +6354,66 @@ static void do_v7m_exception_exit(ARMCPU *cpu) return; } - /* Switch to the target stack. */ + /* Set CONTROL.SPSEL from excret.SPSEL. For QEMU this currently + * causes us to switch the active SP, but we will change this + * later to not do that so we can support v8M. + */ switch_v7m_sp(env, return_to_sp_process); - /* Pop registers. */ - env->regs[0] = v7m_pop(env); - env->regs[1] = v7m_pop(env); - env->regs[2] = v7m_pop(env); - env->regs[3] = v7m_pop(env); - env->regs[12] = v7m_pop(env); - env->regs[14] = v7m_pop(env); - env->regs[15] = v7m_pop(env); - if (env->regs[15] & 1) { - qemu_log_mask(LOG_GUEST_ERROR, - "M profile return from interrupt with misaligned " - "PC is UNPREDICTABLE\n"); - /* Actual hardware seems to ignore the lsbit, and there are several - * RTOSes out there which incorrectly assume the r15 in the stack - * frame should be a Thumb-style "lsbit indicates ARM/Thumb" value. + + { + /* The stack pointer we should be reading the exception frame from + * depends on bits in the magic exception return type value (and + * for v8M isn't necessarily the stack pointer we will eventually + * end up resuming execution with). Get a pointer to the location + * in the CPU state struct where the SP we need is currently being + * stored; we will use and modify it in place. + * We use this limited C variable scope so we don't accidentally + * use 'frame_sp_p' after we do something that makes it invalid. + */ + uint32_t *frame_sp_p = get_v7m_sp_ptr(env, + return_to_secure, + !return_to_handler, + return_to_sp_process); + uint32_t frameptr = *frame_sp_p; + + /* Pop registers. TODO: make these accesses use the correct + * attributes and address space (S/NS, priv/unpriv) and handle + * memory transaction failures. */ - env->regs[15] &= ~1U; + env->regs[0] = ldl_phys(cs->as, frameptr); + env->regs[1] = ldl_phys(cs->as, frameptr + 0x4); + env->regs[2] = ldl_phys(cs->as, frameptr + 0x8); + env->regs[3] = ldl_phys(cs->as, frameptr + 0xc); + env->regs[12] = ldl_phys(cs->as, frameptr + 0x10); + env->regs[14] = ldl_phys(cs->as, frameptr + 0x14); + env->regs[15] = ldl_phys(cs->as, frameptr + 0x18); + if (env->regs[15] & 1) { + qemu_log_mask(LOG_GUEST_ERROR, + "M profile return from interrupt with misaligned " + "PC is UNPREDICTABLE\n"); + /* Actual hardware seems to ignore the lsbit, and there are several + * RTOSes out there which incorrectly assume the r15 in the stack + * frame should be a Thumb-style "lsbit indicates ARM/Thumb" value. + */ + env->regs[15] &= ~1U; + } + xpsr = ldl_phys(cs->as, frameptr + 0x1c); + + /* Commit to consuming the stack frame */ + frameptr += 0x20; + /* Undo stack alignment (the SPREALIGN bit indicates that the original + * pre-exception SP was not 8-aligned and we added a padding word to + * align it, so we undo this by ORing in the bit that increases it + * from the current 8-aligned value to the 8-unaligned value. (Adding 4 + * would work too but a logical OR is how the pseudocode specifies it.) + */ + if (xpsr & XPSR_SPREALIGN) { + frameptr |= 4; + } + *frame_sp_p = frameptr; } - xpsr = v7m_pop(env); + /* This xpsr_write() will invalidate frame_sp_p as it may switch stack */ xpsr_write(env, xpsr, ~XPSR_SPREALIGN); - /* Undo stack alignment. */ - if (xpsr & XPSR_SPREALIGN) { - env->regs[13] |= 4; - } /* The restored xPSR exception field will be zero if we're * resuming in Thread mode. If that doesn't match what the |