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fprobe: Pass entry_data to handlers 

[ Upstream commit 76d0de5729 ]

Pass the private entry_data to the entry and exit handlers so that
they can share the context data, something like saved function
arguments etc.
User must specify the private entry_data size by @entry_data_size
field before registering the fprobe.

Link: https://lkml.kernel.org/r/167526696173.433354.17408372048319432574.stgit@mhiramat.roam.corp.google.com

Cc: Florent Revest <revest@chromium.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Stable-dep-of: 700b2b4397 ("fprobe: Fix to ensure the number of active retprobes is not zero")
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Masami Hiramatsu (Google) 2023-02-02 00:56:01 +09:00 committed by Greg Kroah-Hartman
parent bacf8c749a
commit 0806cb1e6c
5 changed files with 29 additions and 14 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

8
include/linux/fprobe.h
View File

@ -13,6 +13,7 @@
* @nmissed: The counter for missing events. * @nmissed: The counter for missing events.
* @flags: The status flag. * @flags: The status flag.
* @rethook: The rethook data structure. (internal data) * @rethook: The rethook data structure. (internal data)
* @entry_data_size: The private data storage size.
* @entry_handler: The callback function for function entry. * @entry_handler: The callback function for function entry.
* @exit_handler: The callback function for function exit. * @exit_handler: The callback function for function exit.
*/ */
@ -29,9 +30,12 @@ struct fprobe {
unsigned long nmissed; unsigned long nmissed;
unsigned int flags; unsigned int flags;
struct rethook *rethook; struct rethook *rethook;
size_t entry_data_size;
void (*entry_handler)(struct fprobe *fp, unsigned long entry_ip, struct pt_regs *regs); void (*entry_handler)(struct fprobe *fp, unsigned long entry_ip,
void (*exit_handler)(struct fprobe *fp, unsigned long entry_ip, struct pt_regs *regs); struct pt_regs *regs, void *entry_data);
void (*exit_handler)(struct fprobe *fp, unsigned long entry_ip,
struct pt_regs *regs, void *entry_data);
}; };
/* This fprobe is soft-disabled. */ /* This fprobe is soft-disabled. */

2
kernel/trace/bpf_trace.c
View File

@ -2646,7 +2646,7 @@ kprobe_multi_link_prog_run(struct bpf_kprobe_multi_link *link,
static void static void
kprobe_multi_link_handler(struct fprobe *fp, unsigned long fentry_ip, kprobe_multi_link_handler(struct fprobe *fp, unsigned long fentry_ip,
struct pt_regs *regs) struct pt_regs *regs, void *data)
{ {
struct bpf_kprobe_multi_link *link; struct bpf_kprobe_multi_link *link;

21
kernel/trace/fprobe.c
View File

@ -17,14 +17,16 @@
struct fprobe_rethook_node { struct fprobe_rethook_node {
struct rethook_node node; struct rethook_node node;
unsigned long entry_ip; unsigned long entry_ip;
char data[];
}; };
static void fprobe_handler(unsigned long ip, unsigned long parent_ip, static void fprobe_handler(unsigned long ip, unsigned long parent_ip,
struct ftrace_ops *ops, struct ftrace_regs *fregs) struct ftrace_ops *ops, struct ftrace_regs *fregs)
{ {
struct fprobe_rethook_node *fpr; struct fprobe_rethook_node *fpr;
struct rethook_node *rh; struct rethook_node *rh = NULL;
struct fprobe *fp; struct fprobe *fp;
void *entry_data = NULL;
int bit; int bit;
fp = container_of(ops, struct fprobe, ops); fp = container_of(ops, struct fprobe, ops);
@ -37,9 +39,6 @@ static void fprobe_handler(unsigned long ip, unsigned long parent_ip,
return; return;
} }
if (fp->entry_handler)
fp->entry_handler(fp, ip, ftrace_get_regs(fregs));
if (fp->exit_handler) { if (fp->exit_handler) {
rh = rethook_try_get(fp->rethook); rh = rethook_try_get(fp->rethook);
if (!rh) { if (!rh) {
@ -48,9 +47,16 @@ static void fprobe_handler(unsigned long ip, unsigned long parent_ip,
} }
fpr = container_of(rh, struct fprobe_rethook_node, node); fpr = container_of(rh, struct fprobe_rethook_node, node);
fpr->entry_ip = ip; fpr->entry_ip = ip;
rethook_hook(rh, ftrace_get_regs(fregs), true); if (fp->entry_data_size)
entry_data = fpr->data;
} }
if (fp->entry_handler)
fp->entry_handler(fp, ip, ftrace_get_regs(fregs), entry_data);
if (rh)
rethook_hook(rh, ftrace_get_regs(fregs), true);
out: out:
ftrace_test_recursion_unlock(bit); ftrace_test_recursion_unlock(bit);
} }
@ -81,7 +87,8 @@ static void fprobe_exit_handler(struct rethook_node *rh, void *data,
fpr = container_of(rh, struct fprobe_rethook_node, node); fpr = container_of(rh, struct fprobe_rethook_node, node);
fp->exit_handler(fp, fpr->entry_ip, regs); fp->exit_handler(fp, fpr->entry_ip, regs,
fp->entry_data_size ? (void *)fpr->data : NULL);
} }
NOKPROBE_SYMBOL(fprobe_exit_handler); NOKPROBE_SYMBOL(fprobe_exit_handler);
@ -146,7 +153,7 @@ static int fprobe_init_rethook(struct fprobe *fp, int num)
for (i = 0; i < size; i++) { for (i = 0; i < size; i++) {
struct fprobe_rethook_node *node; struct fprobe_rethook_node *node;
node = kzalloc(sizeof(*node), GFP_KERNEL); node = kzalloc(sizeof(*node) + fp->entry_data_size, GFP_KERNEL);
if (!node) { if (!node) {
rethook_free(fp->rethook); rethook_free(fp->rethook);
fp->rethook = NULL; fp->rethook = NULL;

6
lib/test_fprobe.c
View File

@ -30,7 +30,8 @@ static noinline u32 fprobe_selftest_target2(u32 value)
return (value / div_factor) + 1; return (value / div_factor) + 1;
} }
static notrace void fp_entry_handler(struct fprobe *fp, unsigned long ip, struct pt_regs *regs) static notrace void fp_entry_handler(struct fprobe *fp, unsigned long ip,
struct pt_regs *regs, void *data)
{ {
KUNIT_EXPECT_FALSE(current_test, preemptible()); KUNIT_EXPECT_FALSE(current_test, preemptible());
/* This can be called on the fprobe_selftest_target and the fprobe_selftest_target2 */ /* This can be called on the fprobe_selftest_target and the fprobe_selftest_target2 */
@ -39,7 +40,8 @@ static notrace void fp_entry_handler(struct fprobe *fp, unsigned long ip, struct
entry_val = (rand1 / div_factor); entry_val = (rand1 / div_factor);
} }
static notrace void fp_exit_handler(struct fprobe *fp, unsigned long ip, struct pt_regs *regs) static notrace void fp_exit_handler(struct fprobe *fp, unsigned long ip,
struct pt_regs *regs, void *data)
{ {
unsigned long ret = regs_return_value(regs); unsigned long ret = regs_return_value(regs);

6
samples/fprobe/fprobe_example.c
View File

@ -48,7 +48,8 @@ static void show_backtrace(void)
stack_trace_print(stacks, len, 24); stack_trace_print(stacks, len, 24);
} }
static void sample_entry_handler(struct fprobe *fp, unsigned long ip, struct pt_regs *regs) static void sample_entry_handler(struct fprobe *fp, unsigned long ip,
struct pt_regs *regs, void *data)
{ {
if (use_trace) if (use_trace)
/* /*
@ -63,7 +64,8 @@ static void sample_entry_handler(struct fprobe *fp, unsigned long ip, struct pt_
show_backtrace(); show_backtrace();
} }
static void sample_exit_handler(struct fprobe *fp, unsigned long ip, struct pt_regs *regs) static void sample_exit_handler(struct fprobe *fp, unsigned long ip, struct pt_regs *regs,
void *data)
{ {
unsigned long rip = instruction_pointer(regs); unsigned long rip = instruction_pointer(regs);