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Improving maps output. 

Maps output now displays fault address location more intelligently.  If
the fault is not in a mapped region, it now shows where that address is
with respect to the other maps.

In addition, the size of the map is now printed as part of the output.

Also, crasher now supports an "mmap" option which mmaps/munmaps a region
of memory and then attempts to access it, causing a fault address in
between mapped regions that can be used to test that new part of the
maps output.

Change-Id: Ia5e1926802bdfcbbdb7857e3631ddf395ae0c5b8
This commit is contained in:
Brigid Smith 2014-07-07 12:33:50 -07:00
parent f6ef1f53ac
commit 8606eaa770
2 changed files with 27 additions and 17 deletions
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6
debuggerd/crasher.c
View File

@ -7,6 +7,7 @@
#include <stdlib.h>
#include <string.h>
#include <sys/cdefs.h>
#include <sys/mman.h>
#include <sys/ptrace.h>
#include <sys/socket.h>
#include <sys/wait.h>
@ -156,6 +157,10 @@ static int do_action(const char* arg)
return EXIT_SUCCESS;
} else if (!strcmp(arg, "heap-usage")) {
abuse_heap();
} else if (!strcmp(arg, "SIGSEGV-unmapped")) {
char* map = mmap(NULL, sizeof(int), PROT_READ | PROT_WRITE, MAP_SHARED | MAP_ANONYMOUS, -1, 0);
munmap(map, sizeof(int));
map[0] = '8';
}
fprintf(stderr, "%s OP\n", __progname);
@ -175,6 +180,7 @@ static int do_action(const char* arg)
fprintf(stderr, " SIGPIPE cause a SIGPIPE\n");
fprintf(stderr, " SIGSEGV cause a SIGSEGV at address 0x0 (synonym: crash)\n");
fprintf(stderr, " SIGSEGV-non-null cause a SIGSEGV at a non-zero address\n");
fprintf(stderr, " SIGSEGV-unmapped mmap/munmap a region of memory and then attempt to access it\n");
fprintf(stderr, " SIGTRAP cause a SIGTRAP\n");
fprintf(stderr, "prefix any of the above with 'thread-' to not run\n");
fprintf(stderr, "on the process' main thread.\n");

38
debuggerd/tombstone.cpp
View File

@ -329,10 +329,11 @@ static void dump_backtrace_and_stack(Backtrace* backtrace, log_t* log) {
}
static void dump_map(log_t* log, const backtrace_map_t* map, bool fault_addr) {
_LOG(log, logtype::MAPS, "%s%" PRIPTR "-%" PRIPTR " %c%c%c %s\n",
(fault_addr? "--->" : " "), map->start, map->end,
_LOG(log, logtype::MAPS, "%s%" PRIPTR "-%" PRIPTR " %c%c%c %7d %s\n",
(fault_addr? "--->" : " "), map->start, map->end - 1,
(map->flags & PROT_READ) ? 'r' : '-', (map->flags & PROT_WRITE) ? 'w' : '-',
(map->flags & PROT_EXEC) ? 'x' : '-', map->name.c_str());
(map->flags & PROT_EXEC) ? 'x' : '-',
(map->end - map->start), map->name.c_str());
}
static void dump_nearby_maps(BacktraceMap* map, log_t* log, pid_t tid) {
@ -342,28 +343,31 @@ static void dump_nearby_maps(BacktraceMap* map, log_t* log, pid_t tid) {
_LOG(log, logtype::MAPS, "cannot get siginfo for %d: %s\n", tid, strerror(errno));
return;
}
if (!signal_has_si_addr(si.si_signo)) {
return;
}
bool is_running = (si.si_code == SI_USER);
uintptr_t addr = reinterpret_cast<uintptr_t>(si.si_addr);
addr &= ~0xfff; // round to 4K page boundary
if (addr == 0) { // null-pointer deref
if (!is_running && addr == 0) { // null-pointer deref
return;
}
_LOG(log, logtype::MAPS, "\nmemory map: (fault address prefixed with --->)\n");
_LOG(log, logtype::MAPS, "\nmemory map: %s\n", is_running? "" : "(fault address prefixed with --->)");
bool found_map = false;
for (BacktraceMap::const_iterator it = map->begin(); it != map->end(); ++it) {
bool in_map = addr >= (*it).start && addr < (*it).end;
dump_map(log, &*it, in_map);
if(in_map) {
found_map = true;
}
if(!is_running && (addr < map->begin()->start)) {
_LOG(log, logtype::MAPS, "--->Fault address falls at %" PRIPTR " before any mapped regions\n", addr);
}
if(!found_map) {
_LOG(log, logtype::ERROR, "\nFault address was not in any map!");
BacktraceMap::const_iterator prev = map->begin();
for (BacktraceMap::const_iterator it = map->begin(); it != map->end(); ++it) {
if (addr >= (*prev).end && addr < (*it).start) {
_LOG(log, logtype::MAPS, "--->Fault address falls at %" PRIPTR " between mapped regions\n", addr);
}
prev = it;
bool in_map = !is_running && (addr >= (*it).start) && (addr < (*it).end);
dump_map(log, &*it, in_map);
}
if (!is_running && (addr >= (*prev).end)) {
_LOG(log, logtype::MAPS, "--->Fault address falls at %" PRIPTR " after any mapped regions\n", addr);
}
}