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Fatal exceptions: Cleanly deal with exceptions that occur inside fatal_exception_handler_inner()

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In case of heap corruption or some other major problem, dumping details
in the exception handler can cause a crash loop - so fail out if we seem
to be going in circles.
This commit is contained in:
Angus Gratton 2016-05-17 09:08:53 +10:00
parent 981c87899b
commit 1e9296f60c
2 changed files with 33 additions and 18 deletions
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41
core/debug_dumps.c
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@ -24,10 +24,14 @@
/* Forward declarations */
static void IRAM fatal_handler_prelude(void);
/* Inner parts of crash handlers marked noinline to ensure they don't inline into IRAM. */
static void __attribute__((noinline)) __attribute__((noreturn)) fatal_exception_handler_inner(uint32_t *sp, bool registers_saved_on_stack);
/* Inner parts of crash handlers */
typedef void __attribute__((noreturn)) (*fatal_exception_handler_fn)(uint32_t *sp, bool registers_saved_on_stack);
static void __attribute__((noreturn)) standard_fatal_exception_handler_inner(uint32_t *sp, bool registers_saved_on_stack);
static void __attribute__((noreturn)) second_fatal_exception_handler_inner(uint32_t *sp, bool registers_saved_on_stack);
static void __attribute__((noinline)) __attribute__((noreturn)) abort_handler_inner(uint32_t *caller, uint32_t *sp);
static IRAM_DATA fatal_exception_handler_fn fatal_exception_handler_inner = standard_fatal_exception_handler_inner;
/* fatal_exception_handler called from any unhandled user exception
*
* (similar to a hard fault on other processor architectures)
@ -38,7 +42,8 @@ static void __attribute__((noinline)) __attribute__((noreturn)) abort_handler_in
*/
void IRAM __attribute__((noreturn)) fatal_exception_handler(uint32_t *sp, bool registers_saved_on_stack) {
fatal_handler_prelude();
fatal_exception_handler_inner(sp, registers_saved_on_stack);
fatal_exception_handler_fn inner_fn = fatal_exception_handler_inner;
inner_fn(sp, registers_saved_on_stack);
}
/* Abort implementation
@ -132,6 +137,12 @@ void dump_registers_in_exception_handler(uint32_t *sp) {
printf("SAR %08x\n", saved[0x13]);
}
static void __attribute__((noreturn)) post_crash_reset(void) {
uart_flush_txfifo(0);
uart_flush_txfifo(1);
sdk_system_restart_in_nmi();
while(1) {}
}
/* Prelude ensures exceptions/NMI off and flash is mapped, allowing
calls to non-IRAM functions.
@ -150,7 +161,10 @@ static void IRAM fatal_handler_prelude(void) {
/* Main part of fatal exception handler, is run from flash to save
some IRAM.
*/
static void fatal_exception_handler_inner(uint32_t *sp, bool registers_saved_on_stack) {
static void standard_fatal_exception_handler_inner(uint32_t *sp, bool registers_saved_on_stack) {
/* Replace the fatal exception handler 'inner' function so we
don't end up in a crash loop if this handler crashes. */
fatal_exception_handler_inner = second_fatal_exception_handler_inner;
dump_excinfo();
if (sp) {
if (registers_saved_on_stack) {
@ -159,10 +173,16 @@ static void fatal_exception_handler_inner(uint32_t *sp, bool registers_saved_on_
dump_stack(sp);
}
dump_heapinfo();
uart_flush_txfifo(0);
uart_flush_txfifo(1);
sdk_system_restart_in_nmi();
while(1) {}
post_crash_reset();
}
/* This is the exception handler that gets called if a crash occurs inside the standard handler,
so we don't end up in a crash loop. It doesn't rely on contents of stack or heap.
*/
static void second_fatal_exception_handler_inner(uint32_t *sp, bool registers_saved_on_stack) {
dump_excinfo();
printf("Second fatal exception occured inside fatal exception handler. Can't continue.\n");
post_crash_reset();
}
void dump_heapinfo(void)
@ -207,8 +227,5 @@ static void abort_handler_inner(uint32_t *caller, uint32_t *sp) {
printf("abort() invoked at %p.\n", caller);
dump_stack(sp);
dump_heapinfo();
uart_flush_txfifo(0);
uart_flush_txfifo(1);
sdk_system_restart_in_nmi();
while(1) {}
post_crash_reset();
}