diff options
Diffstat (limited to 'vm_dump.c')
| -rw-r--r-- | vm_dump.c | 31 |
1 files changed, 29 insertions, 2 deletions
@@ -442,7 +442,7 @@ darwin_sigtramp: ucontext_t *uctx; char vec[1]; int r; - /* get _sigtramp's ucontext_t and set values to cursor + /* get previous frame information from %rbx at _sigtramp and set values to cursor * http://www.opensource.apple.com/source/Libc/Libc-825.25/i386/sys/_sigtramp.s * http://www.opensource.apple.com/source/libunwind/libunwind-35.1/src/unw_getcontext.s */ @@ -465,8 +465,35 @@ darwin_sigtramp: unw_set_reg(&cursor, UNW_X86_64_R14, uctx->uc_mcontext->__ss.__r14); unw_set_reg(&cursor, UNW_X86_64_R15, uctx->uc_mcontext->__ss.__r15); ip = uctx->uc_mcontext->__ss.__rip; + + /* There's 4 cases for SEGV: + * (1) called invalid address + * (2) read or write invalid address + * (3) received signal + * + * Detail: + * (1) called invalid address + * In this case, saved ip is invalid address. + * It needs to just save the address for the information, + * skip the frame, and restore the frame calling the + * invalid address from %rsp. + * The problem is how to check whether the ip is valid or not. + * This code uses mincore(2) and assume the address's page is + * incore/referenced or not reflects the problem. + * Note that High Sierra's mincore(2) may return -128. + * (2) read or write invalid address + * saved ip is valid. just restart backtracing. + * (3) received signal in user space + * Same as (2). + * (4) received signal in kernel + * In this case saved ip points just after syscall, but registers are + * already overwriten by kernel. To fix register consistency, + * skip libc's kernel wrapper. + * To detect this case, just previous two bytes of ip is "\x0f\x05", + * syscall instruction of x86_64. + */ r = mincore((const void *)ip, 1, vec); - if (r || !vec[0] || memcmp((const char *)ip-2, "\x0f\x05", 2) == 0) { + if (r || vec[0] <= 0 || memcmp((const char *)ip-2, "\x0f\x05", 2) == 0) { /* if segv is caused by invalid call or signal received in syscall */ /* the frame is invalid; skip */ trace[n++] = (void *)ip; |