On 02/16/2017 01:36 PM, Peter Maydell wrote:
Extract the code from the tail end of arm_v7m_do_interrupt() which
enters the exception handler into a pair of utility functions
v7m_exception_taken() and v7m_push_stack(), which correspond roughly
to the pseudocode PushStack() and ExceptionTaken().
This also requires us to move the arm_v7m_load_vector() utility
routine up so we can call it.
Handling illegal exception returns has some cases where we want to
take a UsageFault either on an existing stack frame or with a new
stack frame but with a specific LR value, so we want to be able to
call these without having to go via arm_v7m_cpu_do_interrupt().
Signed-off-by: Peter Maydell <peter.mayd...@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <f4...@amsat.org>
---
target/arm/helper.c | 118 ++++++++++++++++++++++++++++++----------------------
1 file changed, 68 insertions(+), 50 deletions(-)
diff --git a/target/arm/helper.c b/target/arm/helper.c
index 1844852..f94d1c7 100644
--- a/target/arm/helper.c
+++ b/target/arm/helper.c
@@ -6001,6 +6001,72 @@ static void switch_v7m_sp(CPUARMState *env, bool
new_spsel)
}
}
+static uint32_t arm_v7m_load_vector(ARMCPU *cpu)
+{
+ CPUState *cs = CPU(cpu);
+ CPUARMState *env = &cpu->env;
+ MemTxResult result;
+ hwaddr vec = env->v7m.vecbase + env->v7m.exception * 4;
+ uint32_t addr;
+
+ addr = address_space_ldl(cs->as, vec,
+ MEMTXATTRS_UNSPECIFIED, &result);
+ if (result != MEMTX_OK) {
+ /* Architecturally this should cause a HardFault setting HSFR.VECTTBL,
+ * which would then be immediately followed by our failing to load
+ * the entry vector for that HardFault, which is a Lockup case.
+ * Since we don't model Lockup, we just report this guest error
+ * via cpu_abort().
+ */
+ cpu_abort(cs, "Failed to read from exception vector table "
+ "entry %08x\n", (unsigned)vec);
+ }
+ return addr;
+}
+
+static void v7m_exception_taken(ARMCPU *cpu, uint32_t lr)
+{
+ /* Do the "take the exception" parts of exception entry,
+ * but not the pushing of state to the stack. This is
+ * similar to the pseudocode ExceptionTaken() function.
+ */
+ CPUARMState *env = &cpu->env;
+ uint32_t addr;
+
+ armv7m_nvic_acknowledge_irq(env->nvic);
+ switch_v7m_sp(env, 0);
+ /* Clear IT bits */
+ env->condexec_bits = 0;
+ env->regs[14] = lr;
+ addr = arm_v7m_load_vector(cpu);
+ env->regs[15] = addr & 0xfffffffe;
+ env->thumb = addr & 1;
+}
+
+static void v7m_push_stack(ARMCPU *cpu)
+{
+ /* Do the "set up stack frame" part of exception entry,
+ * similar to pseudocode PushStack().
+ */
+ CPUARMState *env = &cpu->env;
+ uint32_t xpsr = xpsr_read(env);
+
+ /* Align stack pointer if the guest wants that */
+ if ((env->regs[13] & 4) && (env->v7m.ccr & R_V7M_CCR_STKALIGN_MASK)) {
+ env->regs[13] -= 4;
+ xpsr |= 0x200;
+ }
+ /* Switch to the handler mode. */
+ v7m_push(env, xpsr);
+ v7m_push(env, env->regs[15]);
+ v7m_push(env, env->regs[14]);
+ v7m_push(env, env->regs[12]);
+ v7m_push(env, env->regs[3]);
+ v7m_push(env, env->regs[2]);
+ v7m_push(env, env->regs[1]);
+ v7m_push(env, env->regs[0]);
+}
+
static void do_v7m_exception_exit(CPUARMState *env)
{
uint32_t type;
@@ -6062,37 +6128,11 @@ static void arm_log_exception(int idx)
}
}
-static uint32_t arm_v7m_load_vector(ARMCPU *cpu)
-
-{
- CPUState *cs = CPU(cpu);
- CPUARMState *env = &cpu->env;
- MemTxResult result;
- hwaddr vec = env->v7m.vecbase + env->v7m.exception * 4;
- uint32_t addr;
-
- addr = address_space_ldl(cs->as, vec,
- MEMTXATTRS_UNSPECIFIED, &result);
- if (result != MEMTX_OK) {
- /* Architecturally this should cause a HardFault setting HSFR.VECTTBL,
- * which would then be immediately followed by our failing to load
- * the entry vector for that HardFault, which is a Lockup case.
- * Since we don't model Lockup, we just report this guest error
- * via cpu_abort().
- */
- cpu_abort(cs, "Failed to read from exception vector table "
- "entry %08x\n", (unsigned)vec);
- }
- return addr;
-}
-
void arm_v7m_cpu_do_interrupt(CPUState *cs)
{
ARMCPU *cpu = ARM_CPU(cs);
CPUARMState *env = &cpu->env;
- uint32_t xpsr = xpsr_read(env);
uint32_t lr;
- uint32_t addr;
arm_log_exception(cs->exception_index);
@@ -6150,31 +6190,9 @@ void arm_v7m_cpu_do_interrupt(CPUState *cs)
return; /* Never happens. Keep compiler happy. */
}
- armv7m_nvic_acknowledge_irq(env->nvic);
-
+ v7m_push_stack(cpu);
+ v7m_exception_taken(cpu, lr);
qemu_log_mask(CPU_LOG_INT, "... as %d\n", env->v7m.exception);
-
- /* Align stack pointer if the guest wants that */
- if ((env->regs[13] & 4) && (env->v7m.ccr & R_V7M_CCR_STKALIGN_MASK)) {
- env->regs[13] -= 4;
- xpsr |= 0x200;
- }
- /* Switch to the handler mode. */
- v7m_push(env, xpsr);
- v7m_push(env, env->regs[15]);
- v7m_push(env, env->regs[14]);
- v7m_push(env, env->regs[12]);
- v7m_push(env, env->regs[3]);
- v7m_push(env, env->regs[2]);
- v7m_push(env, env->regs[1]);
- v7m_push(env, env->regs[0]);
- switch_v7m_sp(env, 0);
- /* Clear IT bits */
- env->condexec_bits = 0;
- env->regs[14] = lr;
- addr = arm_v7m_load_vector(cpu);
- env->regs[15] = addr & 0xfffffffe;
- env->thumb = addr & 1;
}
/* Function used to synchronize QEMU's AArch64 register set with AArch32
