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| author | Mark Johnston <markj@FreeBSD.org> | 2019-02-21 22:54:17 +0000 |
|---|---|---|
| committer | Mark Johnston <markj@FreeBSD.org> | 2019-02-21 22:54:17 +0000 |
| commit | 4f1b715c8487f7a6d45083dbe998e82a971f48b4 (patch) | |
| tree | f9920c102daf3505c78a07f8a93f201192ecf4bb /sys/cddl/dev/dtrace | |
| parent | c0ca37d17b451f3eedbb95041475280b721451a7 (diff) | |
| download | src-4f1b715c8487f7a6d45083dbe998e82a971f48b4.tar.gz src-4f1b715c8487f7a6d45083dbe998e82a971f48b4.zip | |
Fix a tracepoint lookup race in fasttrap_pid_probe().
fasttrap hooks the userspace breakpoint handler; the hook looks up the
breakpoint address in a hash table of tracepoints. It is possible for
the tracepoint to be removed by a different thread in between the
breakpoint trap and the hash table lookup, in which case SIGTRAP gets
delivered to the target process. Fix the problem by adding a
per-process generation counter that gets incremented when a tracepoint
belonging to that process is removed. Then, when a lookup fails, the
trapping instruction is restarted if the thread's counter doesn't match
that of the process.
Reviewed by: cem
MFC after: 2 weeks
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D19273
Notes
Notes:
svn path=/head/; revision=344452
Diffstat (limited to 'sys/cddl/dev/dtrace')
| -rw-r--r-- | sys/cddl/dev/dtrace/dtrace_cddl.h | 5 |
1 files changed, 4 insertions, 1 deletions
diff --git a/sys/cddl/dev/dtrace/dtrace_cddl.h b/sys/cddl/dev/dtrace/dtrace_cddl.h index b69da4d18da1..344fe562bff9 100644 --- a/sys/cddl/dev/dtrace/dtrace_cddl.h +++ b/sys/cddl/dev/dtrace/dtrace_cddl.h @@ -37,7 +37,7 @@ typedef struct kdtrace_proc { u_int64_t p_dtrace_count; /* Number of DTrace tracepoints */ void *p_dtrace_helpers; /* DTrace helpers, if any */ int p_dtrace_model; - + uint64_t p_fasttrap_tp_gen; /* Tracepoint hash table gen */ } kdtrace_proc_t; /* @@ -86,6 +86,7 @@ typedef struct kdtrace_thread { u_int64_t td_hrtime; /* Last time on cpu. */ void *td_dtrace_sscr; /* Saved scratch space location. */ void *td_systrace_args; /* syscall probe arguments. */ + uint64_t td_fasttrap_tp_gen; /* Tracepoint hash table gen. */ } kdtrace_thread_t; /* @@ -113,10 +114,12 @@ typedef struct kdtrace_thread { #define t_dtrace_regv td_dtrace->td_dtrace_regv #define t_dtrace_sscr td_dtrace->td_dtrace_sscr #define t_dtrace_systrace_args td_dtrace->td_systrace_args +#define t_fasttrap_tp_gen td_dtrace->td_fasttrap_tp_gen #define p_dtrace_helpers p_dtrace->p_dtrace_helpers #define p_dtrace_count p_dtrace->p_dtrace_count #define p_dtrace_probes p_dtrace->p_dtrace_probes #define p_model p_dtrace->p_dtrace_model +#define p_fasttrap_tp_gen p_dtrace->p_fasttrap_tp_gen #define DATAMODEL_NATIVE 0 #ifdef __amd64__ |