Commit d9b36549 authored by Ye Bin's avatar Ye Bin
Browse files

tracing/probes: support '%pD' type for print struct file's name 

mainline inclusion
from mainline-v6.10-rc1
commit 20fe4d07bde67ec26716835b61be2c4eeca1c6bc
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/IAMXDU

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=20fe4d07bde67ec26716835b61be2c4eeca1c6bc

--------------------------------

As like '%pd' type, this patch supports print type '%pD' for print file's
name. For example "name=$arg1:%pD" casts the `$arg1` as (struct file*),
dereferences the "file.f_path.dentry.d_name.name" field and stores it to
"name" argument as a kernel string.
Here is an example:
[tracing]# echo 'p:testprobe vfs_read name=$arg1:%pD' > kprobe_event
[tracing]# echo 1 > events/kprobes/testprobe/enable
[tracing]# grep -q "1" events/kprobes/testprobe/enable
[tracing]# echo 0 > events/kprobes/testprobe/enable
[tracing]# grep "vfs_read" trace | grep "enable"
            grep-15108   [003] .....  5228.328609: testprobe: (vfs_read+0x4/0xbb0) name="enable"

Note that this expects the given argument (e.g. $arg1) is an address of struct
file. User must ensure it.

Link: https://lore.kernel.org/all/20240322064308.284457-3-yebin10@huawei.com/


[Masami: replaced "previous patch" with '%pd' type]

Signed-off-by: default avatarYe Bin <yebin10@huawei.com>
Acked-by: default avatarMasami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: default avatarMasami Hiramatsu (Google) <mhiramat@kernel.org>
Conflicts:
	kernel/trace/trace.c
[Fix context diff]
Signed-off-by: default avatarYe Bin <yebin10@huawei.com>
parent c69e430a

kernel/trace/trace.c

+1 −1
Original line number Diff line number Diff line
@@ -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, %pd, <type>\\[<array-size>\\]\n"

	"\t           symstr, %pd/%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"

kernel/trace/trace_probe.c

+35 −22
Original line number Diff line number Diff line
@@ -12,6 +12,7 @@ 
#define pr_fmt(fmt)	"trace_probe: " fmt



#include <linux/bpf.h>

#include <linux/fs.h>

#include "trace_btf.h"



#include "trace_probe.h"
@@ -1585,9 +1586,12 @@ int traceprobe_expand_dentry_args(int argc, const char *argv[], char **buf) 


	used = 0;

	for (i = 0; i < argc; i++) {

		if (glob_match("*:%pd", argv[i])) {

		char *tmp;

		char *equal;

		size_t arg_len;



		if (!glob_match("*:%p[dD]", argv[i]))

			continue;



		if (!tmpbuf) {

			tmpbuf = kmalloc(bufsize, GFP_KERNEL);
@@ -1602,19 +1606,28 @@ int traceprobe_expand_dentry_args(int argc, const char *argv[], char **buf) 
		equal = strchr(tmp, '=');

		if (equal)

			*equal = '\0';

			tmp[strlen(argv[i]) - 4] = '\0';

		arg_len = strlen(argv[i]);

		tmp[arg_len - 4] = '\0';

		if (argv[i][arg_len - 1] == 'd')

			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);

		else

			ret = snprintf(tmpbuf + used, bufsize - used,

				       "%s%s+0x0(+0x%zx(+0x%zx(%s))):string",

				       equal ? tmp : "", equal ? "=" : "",

				       offsetof(struct dentry, d_name.name),

				       offsetof(struct file, f_path.dentry),

				       equal ? equal + 1 : tmp);



		kfree(tmp);

		if (ret >= bufsize - used)

			goto nomem;

		argv[i] = tmpbuf + used;

		used += ret + 1;

	}

	}



	*buf = tmpbuf;

	return 0;