Re: [PATCH 1/3] tracing/probes: support '%pd' type for print struct dentry's name
From: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Date: 2024-01-19 14:57:10
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On Fri, 19 Jan 2024 09:38:46 +0800 Ye Bin [off-list ref] wrote:
Similar to '%pd' for printk, use 'pd' for print struct dentry's name.
No, please use '%pd' as a type instead.
quoted hunk ↗ jump to hunk
Signed-off-by: Ye Bin <redacted> --- kernel/trace/trace_probe.c | 38 ++++++++++++++++++++++++++++++++++++++ 1 file changed, 38 insertions(+)diff --git a/kernel/trace/trace_probe.c b/kernel/trace/trace_probe.c index 4dc74d73fc1d..460f98b85b1c 100644 --- a/kernel/trace/trace_probe.c +++ b/kernel/trace/trace_probe.c@@ -11,6 +11,7 @@ */ #define pr_fmt(fmt) "trace_probe: " fmt +#include <linux/dcache.h> #include <linux/bpf.h> #include "trace_btf.h"@@ -86,6 +87,8 @@ static const struct fetch_type probe_fetch_types[] = { "__data_loc char[]"), __ASSIGN_FETCH_TYPE("symstr", string, string, sizeof(u32), 1, 1, "__data_loc char[]"), + __ASSIGN_FETCH_TYPE("pd", string, string, sizeof(u32), 1, 1, + "__data_loc char[]"),
And you don't need to add a new type. Similar to the preprocessor macro, this should be done before parsing the args. See traceprobe_expand_meta_args(), you can scan the args and search argument end with ':%pd'. If you find that, you can replace it with "+0x%lx(%s):string". Then, you don't need any of these complex fetch type. Thank you,
quoted hunk ↗ jump to hunk
/* Basic types */ ASSIGN_FETCH_TYPE(u8, u8, 0), ASSIGN_FETCH_TYPE(u16, u16, 0),@@ -1090,6 +1093,25 @@ static int __parse_bitfield_probe_arg(const char *bf, return (BYTES_TO_BITS(t->size) < (bw + bo)) ? -EINVAL : 0; } +static char* traceprobe_expand_dentry(const char *argv) +{ + #define DENTRY_EXPAND_LEN 7 /* +0xXX() */ + char *new_argv; + int len = strlen(argv) + 1 + DENTRY_EXPAND_LEN; + + new_argv = kmalloc(len, GFP_KERNEL); + if (!new_argv) + return NULL; + + if (snprintf(new_argv, len, "+0x%lx(%s)", + offsetof(struct dentry, d_name.name), argv) >= len) { + kfree(new_argv); + return NULL; + } + + return new_argv; +} + /* String length checking wrapper */ static int traceprobe_parse_probe_arg_body(const char *argv, ssize_t *size, struct probe_arg *parg,@@ -1099,6 +1121,7 @@ static int traceprobe_parse_probe_arg_body(const char *argv, ssize_t *size, char *t, *t2, *t3; int ret, len; char *arg; + char *org_arg = NULL; arg = kstrdup(argv, GFP_KERNEL); if (!arg)@@ -1182,6 +1205,16 @@ static int traceprobe_parse_probe_arg_body(const char *argv, ssize_t *size, parg->count); } + if (!strcmp("pd", parg->type->name)) { + char *temp; + + temp = traceprobe_expand_dentry(arg); + if (!temp) + goto out; + org_arg = arg; + arg = temp; + } + code = tmp = kcalloc(FETCH_INSN_MAX, sizeof(*code), GFP_KERNEL); if (!code) goto out;@@ -1243,6 +1276,10 @@ static int traceprobe_parse_probe_arg_body(const char *argv, ssize_t *size, goto fail; } } + + if (!strcmp(parg->type->name, "pd")) + code++; + /* If op == DEREF, replace it with STRING */ if (!strcmp(parg->type->name, "ustring") || code->op == FETCH_OP_UDEREF)@@ -1321,6 +1358,7 @@ static int traceprobe_parse_probe_arg_body(const char *argv, ssize_t *size, kfree(tmp); out: kfree(arg); + kfree(org_arg); return ret; }-- 2.31.1
-- Masami Hiramatsu (Google) [off-list ref]