diff options
Diffstat (limited to 'arch/x86/mm/kmemcheck/error.c')
| -rw-r--r-- | arch/x86/mm/kmemcheck/error.c | 229 |
1 files changed, 229 insertions, 0 deletions
diff --git a/arch/x86/mm/kmemcheck/error.c b/arch/x86/mm/kmemcheck/error.c new file mode 100644 index 000000000000..5ec9f5a93f47 --- /dev/null +++ b/arch/x86/mm/kmemcheck/error.c @@ -0,0 +1,229 @@ +#include <linux/interrupt.h> +#include <linux/kdebug.h> +#include <linux/kmemcheck.h> +#include <linux/kernel.h> +#include <linux/types.h> +#include <linux/ptrace.h> +#include <linux/stacktrace.h> +#include <linux/string.h> + +#include "error.h" +#include "shadow.h" + +enum kmemcheck_error_type { + KMEMCHECK_ERROR_INVALID_ACCESS, + KMEMCHECK_ERROR_BUG, +}; + +#define SHADOW_COPY_SIZE (1 << CONFIG_KMEMCHECK_SHADOW_COPY_SHIFT) + +struct kmemcheck_error { + enum kmemcheck_error_type type; + + union { + /* KMEMCHECK_ERROR_INVALID_ACCESS */ + struct { + /* Kind of access that caused the error */ + enum kmemcheck_shadow state; + /* Address and size of the erroneous read */ + unsigned long address; + unsigned int size; + }; + }; + + struct pt_regs regs; + struct stack_trace trace; + unsigned long trace_entries[32]; + + /* We compress it to a char. */ + unsigned char shadow_copy[SHADOW_COPY_SIZE]; + unsigned char memory_copy[SHADOW_COPY_SIZE]; +}; + +/* + * Create a ring queue of errors to output. We can't call printk() directly + * from the kmemcheck traps, since this may call the console drivers and + * result in a recursive fault. + */ +static struct kmemcheck_error error_fifo[CONFIG_KMEMCHECK_QUEUE_SIZE]; +static unsigned int error_count; +static unsigned int error_rd; +static unsigned int error_wr; +static unsigned int error_missed_count; + +static struct kmemcheck_error *error_next_wr(void) +{ + struct kmemcheck_error *e; + + if (error_count == ARRAY_SIZE(error_fifo)) { + ++error_missed_count; + return NULL; + } + + e = &error_fifo[error_wr]; + if (++error_wr == ARRAY_SIZE(error_fifo)) + error_wr = 0; + ++error_count; + return e; +} + +static struct kmemcheck_error *error_next_rd(void) +{ + struct kmemcheck_error *e; + + if (error_count == 0) + return NULL; + + e = &error_fifo[error_rd]; + if (++error_rd == ARRAY_SIZE(error_fifo)) + error_rd = 0; + --error_count; + return e; +} + +static void do_wakeup(unsigned long); +static DECLARE_TASKLET(kmemcheck_tasklet, &do_wakeup, 0); + +/* + * Save the context of an error report. + */ +void kmemcheck_error_save(enum kmemcheck_shadow state, + unsigned long address, unsigned int size, struct pt_regs *regs) +{ + static unsigned long prev_ip; + + struct kmemcheck_error *e; + void *shadow_copy; + void *memory_copy; + + /* Don't report several adjacent errors from the same EIP. */ + if (regs->ip == prev_ip) + return; + prev_ip = regs->ip; + + e = error_next_wr(); + if (!e) + return; + + e->type = KMEMCHECK_ERROR_INVALID_ACCESS; + + e->state = state; + e->address = address; + e->size = size; + + /* Save regs */ + memcpy(&e->regs, regs, sizeof(*regs)); + + /* Save stack trace */ + e->trace.nr_entries = 0; + e->trace.entries = e->trace_entries; + e->trace.max_entries = ARRAY_SIZE(e->trace_entries); + e->trace.skip = 0; + save_stack_trace_bp(&e->trace, regs->bp); + + /* Round address down to nearest 16 bytes */ + shadow_copy = kmemcheck_shadow_lookup(address + & ~(SHADOW_COPY_SIZE - 1)); + BUG_ON(!shadow_copy); + + memcpy(e->shadow_copy, shadow_copy, SHADOW_COPY_SIZE); + + kmemcheck_show_addr(address); + memory_copy = (void *) (address & ~(SHADOW_COPY_SIZE - 1)); + memcpy(e->memory_copy, memory_copy, SHADOW_COPY_SIZE); + kmemcheck_hide_addr(address); + + tasklet_hi_schedule_first(&kmemcheck_tasklet); +} + +/* + * Save the context of a kmemcheck bug. + */ +void kmemcheck_error_save_bug(struct pt_regs *regs) +{ + struct kmemcheck_error *e; + + e = error_next_wr(); + if (!e) + return; + + e->type = KMEMCHECK_ERROR_BUG; + + memcpy(&e->regs, regs, sizeof(*regs)); + + e->trace.nr_entries = 0; + e->trace.entries = e->trace_entries; + e->trace.max_entries = ARRAY_SIZE(e->trace_entries); + e->trace.skip = 1; + save_stack_trace(&e->trace); + + tasklet_hi_schedule_first(&kmemcheck_tasklet); +} + +void kmemcheck_error_recall(void) +{ + static const char *desc[] = { + [KMEMCHECK_SHADOW_UNALLOCATED] = "unallocated", + [KMEMCHECK_SHADOW_UNINITIALIZED] = "uninitialized", + [KMEMCHECK_SHADOW_INITIALIZED] = "initialized", + [KMEMCHECK_SHADOW_FREED] = "freed", + }; + + static const char short_desc[] = { + [KMEMCHECK_SHADOW_UNALLOCATED] = 'a', + [KMEMCHECK_SHADOW_UNINITIALIZED] = 'u', + [KMEMCHECK_SHADOW_INITIALIZED] = 'i', + [KMEMCHECK_SHADOW_FREED] = 'f', + }; + + struct kmemcheck_error *e; + unsigned int i; + + e = error_next_rd(); + if (!e) + return; + + switch (e->type) { + case KMEMCHECK_ERROR_INVALID_ACCESS: + printk(KERN_ERR "WARNING: kmemcheck: Caught %d-bit read " + "from %s memory (%p)\n", + 8 * e->size, e->state < ARRAY_SIZE(desc) ? + desc[e->state] : "(invalid shadow state)", + (void *) e->address); + + printk(KERN_INFO); + for (i = 0; i < SHADOW_COPY_SIZE; ++i) + printk("%02x", e->memory_copy[i]); + printk("\n"); + + printk(KERN_INFO); + for (i = 0; i < SHADOW_COPY_SIZE; ++i) { + if (e->shadow_copy[i] < ARRAY_SIZE(short_desc)) + printk(" %c", short_desc[e->shadow_copy[i]]); + else + printk(" ?"); + } + printk("\n"); + printk(KERN_INFO "%*c\n", 2 + 2 + * (int) (e->address & (SHADOW_COPY_SIZE - 1)), '^'); + break; + case KMEMCHECK_ERROR_BUG: + printk(KERN_EMERG "ERROR: kmemcheck: Fatal error\n"); + break; + } + + __show_regs(&e->regs, 1); + print_stack_trace(&e->trace, 0); +} + +static void do_wakeup(unsigned long data) +{ + while (error_count > 0) + kmemcheck_error_recall(); + + if (error_missed_count > 0) { + printk(KERN_WARNING "kmemcheck: Lost %d error reports because " + "the queue was too small\n", error_missed_count); + error_missed_count = 0; + } +} |