On Mon, 26 Feb 2018 09:38:18 +0900 Namhyung Kim namhyung@kernel.org wrote:
Hi Masami,
On Sat, Feb 24, 2018 at 02:28:52PM +0900, Masami Hiramatsu wrote:
In Documentation/trace/kprobetrace.txt, it says
@SYM[+|-offs] : Fetch memory at SYM +|- offs (SYM should be a data symbol)
However, the parser doesn't parse minus offset correctly, since commit 2fba0c8867af ("tracing/kprobes: Fix probe offset to be unsigned") drops minus ("-") offset support for kprobe probe address usage.
This fixes the traceprobe_split_symbol_offset() to parse minus offset again with checking the offset range, and add a minus offset check in kprobe probe address usage.
Fixes: 2fba0c8867af ("tracing/kprobes: Fix probe offset to be unsigned") Signed-off-by: Masami Hiramatsu mhiramat@kernel.org
Changes in v3:
- Use kstrtol instead of kstrtoul. (Thanks Namhyung!)
kernel/trace/trace_kprobe.c | 4 ++-- kernel/trace/trace_probe.c | 8 +++----- kernel/trace/trace_probe.h | 2 +- 3 files changed, 6 insertions(+), 8 deletions(-)
diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c index 5ce9b8cf7be3..b5b1d8aa47d6 100644 --- a/kernel/trace/trace_kprobe.c +++ b/kernel/trace/trace_kprobe.c @@ -667,7 +667,7 @@ static int create_trace_kprobe(int argc, char **argv) char *symbol = NULL, *event = NULL, *group = NULL; int maxactive = 0; char *arg;
- unsigned long offset = 0;
- long offset = 0; void *addr = NULL; char buf[MAX_EVENT_NAME_LEN];
@@ -755,7 +755,7 @@ static int create_trace_kprobe(int argc, char **argv) symbol = argv[1]; /* TODO: support .init module functions */ ret = traceprobe_split_symbol_offset(symbol, &offset);
if (ret) {
if (ret || offset < 0) {Hmm.. is minus offset an error? Then why not removing it from the documentation? And the 'ret' would be 0 in that case.
Yes, since the kprobe.offset is unsigned, it is not possible. BTW, I found it is "unsigned int", so it should check UINT_MAX too... (Or make it unsigned long)
pr_info("Failed to parse either an address or a symbol.\n"); return ret; }diff --git a/kernel/trace/trace_probe.c b/kernel/trace/trace_probe.c index d59357308677..d3d1ee820336 100644 --- a/kernel/trace/trace_probe.c +++ b/kernel/trace/trace_probe.c @@ -320,7 +320,7 @@ static fetch_func_t get_fetch_size_function(const struct fetch_type *type, } /* Split symbol and offset. */ -int traceprobe_split_symbol_offset(char *symbol, unsigned long *offset) +int traceprobe_split_symbol_offset(char *symbol, long *offset) { char *tmp; int ret; @@ -328,13 +328,11 @@ int traceprobe_split_symbol_offset(char *symbol, unsigned long *offset) if (!offset) return -EINVAL;
- tmp = strchr(symbol, '+');
- tmp = strpbrk(symbol, "+-"); if (tmp) {
/* skip sign because kstrtoul doesn't accept '+' */ret = kstrtoul(tmp + 1, 0, offset);
ret = kstrtol(tmp + 1, 0, offset);It should not skip the sign anymore.
Oops, yes. I'll fix it and I should add a test case for it. Thanks!
Thanks, Namhyung
if (ret) return ret;
- *tmp = '\0'; } else *offset = 0;
diff --git a/kernel/trace/trace_probe.h b/kernel/trace/trace_probe.h index 0745f895f780..75daff22ccea 100644 --- a/kernel/trace/trace_probe.h +++ b/kernel/trace/trace_probe.h @@ -365,7 +365,7 @@ extern int traceprobe_conflict_field_name(const char *name, extern void traceprobe_update_arg(struct probe_arg *arg); extern void traceprobe_free_probe_arg(struct probe_arg *arg); -extern int traceprobe_split_symbol_offset(char *symbol, unsigned long *offset); +extern int traceprobe_split_symbol_offset(char *symbol, long *offset); /* Sum up total data length for dynamic arraies (strings) */ static nokprobe_inline int