mainline inclusion from mainline-v6.10-rc1 commit d9b15224dd8ff83b2aef87e4cd5ad10c875ef7d6 category: feature bugzilla: https://gitee.com/openeuler/kernel/issues/IAMXDU
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i...
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During fault locating, the file name needs to be printed based on the dentry address. The offset needs to be calculated each time, which is troublesome. Similar to printk, kprobe support print type '%pd' for print dentry's name. For example "name=$arg1:%pd" casts the `$arg1` as (struct dentry *), dereferences the "d_name.name" field and stores it to "name" argument as a kernel string. Here is an example: [tracing]# echo 'p:testprobe dput name=$arg1:%pd' > kprobe_events [tracing]# echo 1 > events/kprobes/testprobe/enable [tracing]# grep -q "1" events/kprobes/testprobe/enable [tracing]# echo 0 > events/kprobes/testprobe/enable [tracing]# cat trace | grep "enable" bash-14844 [002] ..... 16912.889543: testprobe: (dput+0x4/0x30) name="enable" grep-15389 [003] ..... 16922.834182: testprobe: (dput+0x4/0x30) name="enable" grep-15389 [003] ..... 16922.836103: testprobe: (dput+0x4/0x30) name="enable" bash-14844 [001] ..... 16931.820909: testprobe: (dput+0x4/0x30) name="enable"
Note that this expects the given argument (e.g. $arg1) is an address of struct dentry. User must ensure it.
Link: https://lore.kernel.org/all/20240322064308.284457-2-yebin10@huawei.com/
Signed-off-by: Ye Bin yebin10@huawei.com Acked-by: Masami Hiramatsu (Google) mhiramat@kernel.org Signed-off-by: Masami Hiramatsu (Google) mhiramat@kernel.org Conflicts: kernel/trace/trace.c [Fix context diff] Signed-off-by: Ye Bin yebin10@huawei.com --- kernel/trace/trace.c | 2 +- kernel/trace/trace_fprobe.c | 6 +++++ kernel/trace/trace_kprobe.c | 6 +++++ kernel/trace/trace_probe.c | 50 +++++++++++++++++++++++++++++++++++++ kernel/trace/trace_probe.h | 2 ++ 5 files changed, 65 insertions(+), 1 deletion(-)
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index c0831e6690d2..d58863d42179 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -5763,7 +5763,7 @@ static const char readme_msg[] = "\t +|-[u]<offset>(<fetcharg>), \imm-value, \"imm-string"\n" "\t type: s8/16/32/64, u8/16/32/64, x8/16/32/64, char, string, symbol,\n" "\t b<bit-width>@<bit-offset>/<container-size>, ustring,\n" - "\t symstr, <type>\[<array-size>\]\n" + "\t symstr, %pd, <type>\[<array-size>\]\n" #ifdef CONFIG_HIST_TRIGGERS "\t field: <stype> <name>;\n" "\t stype: u8/u16/u32/u64, s8/s16/s32/s64, pid_t,\n" diff --git a/kernel/trace/trace_fprobe.c b/kernel/trace/trace_fprobe.c index 7d2ddbcfa377..988d68e906ad 100644 --- a/kernel/trace/trace_fprobe.c +++ b/kernel/trace/trace_fprobe.c @@ -976,6 +976,7 @@ static int __trace_fprobe_create(int argc, const char *argv[]) char gbuf[MAX_EVENT_NAME_LEN]; char sbuf[KSYM_NAME_LEN]; char abuf[MAX_BTF_ARGS_LEN]; + char *dbuf = NULL; bool is_tracepoint = false; struct tracepoint *tpoint = NULL; struct traceprobe_parse_context ctx = { @@ -1086,6 +1087,10 @@ static int __trace_fprobe_create(int argc, const char *argv[]) argv = new_argv; }
+ ret = traceprobe_expand_dentry_args(argc, argv, &dbuf); + if (ret) + goto out; + /* setup a probe */ tf = alloc_trace_fprobe(group, event, symbol, tpoint, maxactive, argc, is_return); @@ -1131,6 +1136,7 @@ static int __trace_fprobe_create(int argc, const char *argv[]) trace_probe_log_clear(); kfree(new_argv); kfree(symbol); + kfree(dbuf); return ret;
parse_error: diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c index 47812aa16bb5..0d0ebdf13ae8 100644 --- a/kernel/trace/trace_kprobe.c +++ b/kernel/trace/trace_kprobe.c @@ -779,6 +779,7 @@ static int __trace_kprobe_create(int argc, const char *argv[]) char buf[MAX_EVENT_NAME_LEN]; char gbuf[MAX_EVENT_NAME_LEN]; char abuf[MAX_BTF_ARGS_LEN]; + char *dbuf = NULL; struct traceprobe_parse_context ctx = { .flags = TPARG_FL_KERNEL };
switch (argv[0][0]) { @@ -930,6 +931,10 @@ static int __trace_kprobe_create(int argc, const char *argv[]) argv = new_argv; }
+ ret = traceprobe_expand_dentry_args(argc, argv, &dbuf); + if (ret) + goto out; + /* setup a probe */ tk = alloc_trace_kprobe(group, event, addr, symbol, offset, maxactive, argc, is_return); @@ -971,6 +976,7 @@ static int __trace_kprobe_create(int argc, const char *argv[]) trace_probe_log_clear(); kfree(new_argv); kfree(symbol); + kfree(dbuf); return ret;
parse_error: diff --git a/kernel/trace/trace_probe.c b/kernel/trace/trace_probe.c index ae162ba36a48..ddc0dd24d014 100644 --- a/kernel/trace/trace_probe.c +++ b/kernel/trace/trace_probe.c @@ -1573,6 +1573,56 @@ const char **traceprobe_expand_meta_args(int argc, const char *argv[], return ERR_PTR(ret); }
+/* @buf: *buf must be equal to NULL. Caller must to free *buf */ +int traceprobe_expand_dentry_args(int argc, const char *argv[], char **buf) +{ + int i, used, ret; + const int bufsize = MAX_DENTRY_ARGS_LEN; + char *tmpbuf = NULL; + + if (*buf) + return -EINVAL; + + used = 0; + for (i = 0; i < argc; i++) { + if (glob_match("*:%pd", argv[i])) { + char *tmp; + char *equal; + + if (!tmpbuf) { + tmpbuf = kmalloc(bufsize, GFP_KERNEL); + if (!tmpbuf) + return -ENOMEM; + } + + tmp = kstrdup(argv[i], GFP_KERNEL); + if (!tmp) + goto nomem; + + equal = strchr(tmp, '='); + if (equal) + *equal = '\0'; + tmp[strlen(argv[i]) - 4] = '\0'; + ret = snprintf(tmpbuf + used, bufsize - used, + "%s%s+0x0(+0x%zx(%s)):string", + equal ? tmp : "", equal ? "=" : "", + offsetof(struct dentry, d_name.name), + equal ? equal + 1 : tmp); + kfree(tmp); + if (ret >= bufsize - used) + goto nomem; + argv[i] = tmpbuf + used; + used += ret + 1; + } + } + + *buf = tmpbuf; + return 0; +nomem: + kfree(tmpbuf); + return -ENOMEM; +} + void traceprobe_finish_parse(struct traceprobe_parse_context *ctx) { clear_btf_context(ctx); diff --git a/kernel/trace/trace_probe.h b/kernel/trace/trace_probe.h index c1877d018269..3d22fba4b63f 100644 --- a/kernel/trace/trace_probe.h +++ b/kernel/trace/trace_probe.h @@ -34,6 +34,7 @@ #define MAX_ARRAY_LEN 64 #define MAX_ARG_NAME_LEN 32 #define MAX_BTF_ARGS_LEN 128 +#define MAX_DENTRY_ARGS_LEN 256 #define MAX_STRING_SIZE PATH_MAX #define MAX_ARG_BUF_LEN (MAX_TRACE_ARGS * MAX_ARG_NAME_LEN)
@@ -402,6 +403,7 @@ extern int traceprobe_parse_probe_arg(struct trace_probe *tp, int i, const char **traceprobe_expand_meta_args(int argc, const char *argv[], int *new_argc, char *buf, int bufsize, struct traceprobe_parse_context *ctx); +extern int traceprobe_expand_dentry_args(int argc, const char *argv[], char **buf);
extern int traceprobe_update_arg(struct probe_arg *arg); extern void traceprobe_free_probe_arg(struct probe_arg *arg);