From 8606eaa7700609a2f9f2383b954b4e64dbc4c827 Mon Sep 17 00:00:00 2001 From: Brigid Smith Date: Mon, 7 Jul 2014 12:33:50 -0700 Subject: [PATCH] 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 --- debuggerd/crasher.c | 6 ++++++ debuggerd/tombstone.cpp | 38 +++++++++++++++++++++----------------- 2 files changed, 27 insertions(+), 17 deletions(-) diff --git a/debuggerd/crasher.c b/debuggerd/crasher.c index e11d9af7f..9df3c6464 100644 --- a/debuggerd/crasher.c +++ b/debuggerd/crasher.c @@ -7,6 +7,7 @@ #include #include #include +#include #include #include #include @@ -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"); diff --git a/debuggerd/tombstone.cpp b/debuggerd/tombstone.cpp index dea016d2c..2bb9efdf1 100755 --- a/debuggerd/tombstone.cpp +++ b/debuggerd/tombstone.cpp @@ -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(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); } }