From 8a5e6a99faca360fe3fca8a447528ddc450aebc8 Mon Sep 17 00:00:00 2001 From: kib Date: Tue, 26 Nov 2013 19:54:12 +0000 Subject: [PATCH] Use sysctl KERN_PROC_SIGTRAMP to retrieve the signal trampoline location for the native amd64 ABI. This fixes unwinding over the signal frame after trampoline was moved to the shared page. The code would be more correct if using sysctl for the target process instead of inspecting gdb' own trampoline, but the current change is least intrusive and currently, we always initialize the native ABI sysvec first, which means that trampoline location for FreeBSD/amd64 ABI is relatively stable. Similar change will benefit libunwind. Analyzed by: avg Sponsored by: The FreeBSD Foundation MFC after: 1 week --- contrib/gdb/gdb/amd64fbsd-nat.c | 24 ++++++++++++------------ 1 file changed, 12 insertions(+), 12 deletions(-) diff --git a/contrib/gdb/gdb/amd64fbsd-nat.c b/contrib/gdb/gdb/amd64fbsd-nat.c index f08373422c29..dacd4a37427b 100644 --- a/contrib/gdb/gdb/amd64fbsd-nat.c +++ b/contrib/gdb/gdb/amd64fbsd-nat.c @@ -29,6 +29,7 @@ #include #include #include +#include #include #ifdef HAVE_SYS_PROCFS_H @@ -212,24 +213,23 @@ Please report this to .", SC_RBP_OFFSET = offset; - /* FreeBSD provides a kern.ps_strings sysctl that we can use to + /* FreeBSD provides a kern.proc.sigtramp sysctl that we can use to locate the sigtramp. That way we can still recognize a sigtramp - if its location is changed in a new kernel. Of course this is - still based on the assumption that the sigtramp is placed - directly under the location where the program arguments and - environment can be found. */ + if its location is changed in a new kernel. */ { - int mib[2]; - long ps_strings; + int mib[4]; + struct kinfo_sigtramp kst; size_t len; mib[0] = CTL_KERN; - mib[1] = KERN_PS_STRINGS; - len = sizeof (ps_strings); - if (sysctl (mib, 2, &ps_strings, &len, NULL, 0) == 0) + mib[1] = KERN_PROC; + mib[2] = KERN_PROC_SIGTRAMP; + mib[3] = getpid(); + len = sizeof (kst); + if (sysctl (mib, sizeof(mib) / sizeof(mib[0]), &kst, &len, NULL, 0) == 0) { - amd64fbsd_sigtramp_start_addr = ps_strings - 32; - amd64fbsd_sigtramp_end_addr = ps_strings; + amd64fbsd_sigtramp_start_addr = kst.ksigtramp_start; + amd64fbsd_sigtramp_end_addr = kst.ksigtramp_end; } } }