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authorAndy McFadden <fadden@android.com>2011-09-22 16:37:06 -0700
committerAndy McFadden <fadden@android.com>2011-10-13 12:35:55 -0700
commit136dcc5ce628a1ba600a6818e5cb24d5f15eb016 (patch)
tree51cf599e72e5da60703930198e277d9fa5ac1c2c /debuggerd/arm
parentd707fb3fb6448be04d6e14f7e478df7e298ebf35 (diff)
Show maps near native fault address
This adds some additional output to native crashes. For example, if something tried to access a bit of mmap(/dev/zero) memory that had been mprotect()ed, you might see output like this: I DEBUG : memory map around addr 4015a00c: I DEBUG : 40159000-4015a000 /system/lib/libstdc++.so I DEBUG : 4015a000-40162000 /dev/zero I DEBUG : b0001000-b0009000 /system/bin/linker The idea is to see what's in and around the fault address to make it easier to identify bus errors due to file truncation and segmentation faults caused by buffer over/underruns. No output is generated for accesses below 0x1000 (which are likely NULL pointer dereferences) or for signals that don't set si_addr. Also, suppress the fault address for signals that don't set si_addr: I DEBUG : signal 6 (SIGABRT), code 0 (?), fault addr -------- We still print "fault addr" followed by 8 characters for anything that is parsing the contents. The "address" shown for signals like SIGABRT was meaningless and possibly confusing. Bug 5358516 Change-Id: Icae8ef309ea2d89b129f68d30f96b2ca8a69cc6c
Diffstat (limited to 'debuggerd/arm')
-rw-r--r--debuggerd/arm/machine.c70
1 files changed, 70 insertions, 0 deletions
diff --git a/debuggerd/arm/machine.c b/debuggerd/arm/machine.c
index 88bf054ff..58a7839bc 100644
--- a/debuggerd/arm/machine.c
+++ b/debuggerd/arm/machine.c
@@ -50,6 +50,74 @@ extern int unwind_backtrace_with_ptrace(int tfd, pid_t pid, mapinfo *map,
int *frame0_pc_sane,
bool at_fault);
+/*
+ * If this isn't clearly a null pointer dereference, dump the
+ * /proc/maps entries near the fault address.
+ */
+static void show_nearby_maps(int tfd, int pid, mapinfo *map)
+{
+ siginfo_t si;
+
+ memset(&si, 0, sizeof(si));
+ if (ptrace(PTRACE_GETSIGINFO, pid, 0, &si)) {
+ _LOG(tfd, false, "cannot get siginfo: %s\n", strerror(errno));
+ return;
+ }
+ if (!signal_has_address(si.si_signo))
+ return;
+
+ uintptr_t addr = (uintptr_t) si.si_addr;
+ addr &= ~0xfff; /* round to 4K page boundary */
+ if (addr == 0) /* null-pointer deref */
+ return;
+
+ _LOG(tfd, false, "\nmemory map around addr %08x:\n", si.si_addr);
+
+ /*
+ * Search for a match, or for a hole where the match would be. The list
+ * is backward from the file content, so it starts at high addresses.
+ */
+ bool found = false;
+ mapinfo *next = NULL;
+ mapinfo *prev = NULL;
+ while (map != NULL) {
+ if (addr >= map->start && addr < map->end) {
+ found = true;
+ next = map->next;
+ break;
+ } else if (addr >= map->end) {
+ /* map would be between "prev" and this entry */
+ next = map;
+ map = NULL;
+ break;
+ }
+
+ prev = map;
+ map = map->next;
+ }
+
+ /*
+ * Show "next" then "match" then "prev" so that the addresses appear in
+ * ascending order (like /proc/pid/maps).
+ */
+ if (next != NULL) {
+ _LOG(tfd, false, "%08x-%08x %s\n", next->start, next->end, next->name);
+ } else {
+ _LOG(tfd, false, "(no map below)\n");
+ }
+ if (map != NULL) {
+ _LOG(tfd, false, "%08x-%08x %s\n", map->start, map->end, map->name);
+ } else {
+ _LOG(tfd, false, "(no map for address)\n");
+ }
+ if (prev != NULL) {
+ _LOG(tfd, false, "%08x-%08x %s\n", prev->start, prev->end, prev->name);
+ } else {
+ _LOG(tfd, false, "(no map above)\n");
+ }
+}
+
+
void dump_stack_and_code(int tfd, int pid, mapinfo *map,
int unwind_depth, unsigned int sp_list[],
bool at_fault)
@@ -123,6 +191,8 @@ void dump_stack_and_code(int tfd, int pid, mapinfo *map,
}
}
+ show_nearby_maps(tfd, pid, map);
+
p = sp - 64;
if (p > sp)
p = 0;