[PATCH v2 5/5] uprobes: make uprobe_register() return struct uprobe *

Oleg Nesterov
2024-07-29T13:45:44Z

This way uprobe_unregister() and uprobe_apply() can use "struct uprobe *"
rather than inode + offset. This simplifies the code and allows to avoid
the unnecessary find_uprobe() + put_uprobe() in these functions.

TODO: uprobe_unregister() still needs get_uprobe/put_uprobe to ensure that
this uprobe can't be freed before up_write(&uprobe->register_rwsem).

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
---
include/linux/uprobes.h | 15 +++++-----
kernel/events/uprobes.c | 56 +++++++++++++++----------------------
kernel/trace/bpf_trace.c | 25 ++++++++---------
kernel/trace/trace_uprobe.c | 26 ++++++++---------
4 files changed, 55 insertions(+), 67 deletions(-)

diff --git a/include/linux/uprobes.h b/include/linux/uprobes.h
index 440316fbf3c6..137ddfc0b2f8 100644
--- a/include/linux/uprobes.h
+++ b/include/linux/uprobes.h
@@ -16,6 +16,7 @@
#include <linux/types.h>
#include <linux/wait.h>

+struct uprobe;
struct vm_area_struct;
struct mm_struct;
struct inode;
@@ -110,9 +111,9 @@ extern bool is_trap_insn(uprobe_opcode_t *insn);
extern unsigned long uprobe_get_swbp_addr(struct pt_regs *regs);
extern unsigned long uprobe_get_trap_addr(struct pt_regs *regs);
extern int uprobe_write_opcode(struct arch_uprobe *auprobe, struct mm_struct *mm, unsigned long vaddr, uprobe_opcode_t);
-extern int uprobe_register(struct inode *inode, loff_t offset, loff_t ref_ctr_offset, struct uprobe_consumer *uc);
-extern int uprobe_apply(struct inode *inode, loff_t offset, struct uprobe_consumer *uc, bool);
-extern void uprobe_unregister(struct inode *inode, loff_t offset, struct uprobe_consumer *uc);
+extern struct uprobe *uprobe_register(struct inode *inode, loff_t offset, loff_t ref_ctr_offset, struct uprobe_consumer *uc);
+extern int uprobe_apply(struct uprobe *uprobe, struct uprobe_consumer *uc, bool);
+extern void uprobe_unregister(struct uprobe *uprobe, struct uprobe_consumer *uc);
extern int uprobe_mmap(struct vm_area_struct *vma);
extern void uprobe_munmap(struct vm_area_struct *vma, unsigned long start, unsigned long end);
extern void uprobe_start_dup_mmap(void);
@@ -150,18 +151,18 @@ static inline void uprobes_init(void)

#define uprobe_get_trap_addr(regs) instruction_pointer(regs)

-static inline int
+static inline struct uprobe *
uprobe_register(struct inode *inode, loff_t offset, loff_t ref_ctr_offset, struct uprobe_consumer *uc)
{
- return -ENOSYS;
+ return ERR_PTR(-ENOSYS);
}
static inline int
-uprobe_apply(struct inode *inode, loff_t offset, struct uprobe_consumer *uc, bool add)
+uprobe_apply(struct uprobe* uprobe, struct uprobe_consumer *uc, bool add)
{
return -ENOSYS;
}
static inline void
-uprobe_unregister(struct inode *inode, loff_t offset, struct uprobe_consumer *uc)
+uprobe_unregister(struct uprobe *uprobe, struct uprobe_consumer *uc)
{
}
static inline int uprobe_mmap(struct vm_area_struct *vma)
diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
index b7f40bad8abc..974474680820 100644
--- a/kernel/events/uprobes.c
+++ b/kernel/events/uprobes.c
@@ -1099,20 +1099,14 @@ __uprobe_unregister(struct uprobe *uprobe, struct uprobe_consumer *uc)
delete_uprobe(uprobe);
}

-/*
+/**
* uprobe_unregister - unregister an already registered probe.
- * @inode: the file in which the probe has to be removed.
- * @offset: offset from the start of the file.
+ * @uprobe: uprobe to remove
* @uc: identify which probe if multiple probes are colocated.
*/
-void uprobe_unregister(struct inode *inode, loff_t offset, struct uprobe_consumer *uc)
+void uprobe_unregister(struct uprobe *uprobe, struct uprobe_consumer *uc)
{
- struct uprobe *uprobe;
-
- uprobe = find_uprobe(inode, offset);
- if (WARN_ON(!uprobe))
- return;
-
+ get_uprobe(uprobe);
down_write(&uprobe->register_rwsem);
__uprobe_unregister(uprobe, uc);
up_write(&uprobe->register_rwsem);
@@ -1120,7 +1114,7 @@ void uprobe_unregister(struct inode *inode, loff_t offset, struct uprobe_consume
}
EXPORT_SYMBOL_GPL(uprobe_unregister);

-/*
+/**
* uprobe_register - register a probe
* @inode: the file in which the probe has to be placed.
* @offset: offset from the start of the file.
@@ -1136,40 +1130,40 @@ EXPORT_SYMBOL_GPL(uprobe_unregister);
* unregisters. Caller of uprobe_register() is required to keep @inode
* (and the containing mount) referenced.
*
- * Return errno if it cannot successully install probes
- * else return 0 (success)
+ * Return: pointer to the new uprobe on success or an ERR_PTR on failure.
*/
-int uprobe_register(struct inode *inode, loff_t offset, loff_t ref_ctr_offset,
- struct uprobe_consumer *uc)
+struct uprobe *uprobe_register(struct inode *inode,
+ loff_t offset, loff_t ref_ctr_offset,
+ struct uprobe_consumer *uc)
{
struct uprobe *uprobe;
int ret;

/* Uprobe must have at least one set consumer */
if (!uc->handler && !uc->ret_handler)
- return -EINVAL;
+ return ERR_PTR(-EINVAL);

/* copy_insn() uses read_mapping_page() or shmem_read_mapping_page() */
if (!inode->i_mapping->a_ops->read_folio &&
!shmem_mapping(inode->i_mapping))
- return -EIO;
+ return ERR_PTR(-EIO);
/* Racy, just to catch the obvious mistakes */
if (offset > i_size_read(inode))
- return -EINVAL;
+ return ERR_PTR(-EINVAL);

/*
* This ensures that copy_from_page(), copy_to_page() and
* __update_ref_ctr() can't cross page boundary.
*/
if (!IS_ALIGNED(offset, UPROBE_SWBP_INSN_SIZE))
- return -EINVAL;
+ return ERR_PTR(-EINVAL);
if (!IS_ALIGNED(ref_ctr_offset, sizeof(short)))
- return -EINVAL;
+ return ERR_PTR(-EINVAL);

retry:
uprobe = alloc_uprobe(inode, offset, ref_ctr_offset);
if (IS_ERR(uprobe))
- return PTR_ERR(uprobe);
+ return uprobe;

/*
* We can race with uprobe_unregister()->delete_uprobe().
@@ -1188,35 +1182,29 @@ int uprobe_register(struct inode *inode, loff_t offset, loff_t ref_ctr_offset,

if (unlikely(ret == -EAGAIN))
goto retry;
- return ret;
+
+ return ret ? ERR_PTR(ret) : uprobe;
}
EXPORT_SYMBOL_GPL(uprobe_register);

-/*
- * uprobe_apply - unregister an already registered probe.
- * @inode: the file in which the probe has to be removed.
- * @offset: offset from the start of the file.
+/**
+ * uprobe_apply - add or remove the breakpoints according to @uc->filter
+ * @uprobe: uprobe which "owns" the breakpoint
* @uc: consumer which wants to add more or remove some breakpoints
* @add: add or remove the breakpoints
+ * Return: 0 on success or negative error code.
*/
-int uprobe_apply(struct inode *inode, loff_t offset,
- struct uprobe_consumer *uc, bool add)
+int uprobe_apply(struct uprobe *uprobe, struct uprobe_consumer *uc, bool add)
{
- struct uprobe *uprobe;
struct uprobe_consumer *con;
int ret = -ENOENT;

- uprobe = find_uprobe(inode, offset);
- if (WARN_ON(!uprobe))
- return ret;
-
down_write(&uprobe->register_rwsem);
for (con = uprobe->consumers; con && con != uc ; con = con->next)
;
if (con)
ret = register_for_each_vma(uprobe, add ? uc : NULL);
up_write(&uprobe->register_rwsem);
- put_uprobe(uprobe);

return ret;
}
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index afa909e17824..4e391daafa64 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -3160,6 +3160,7 @@ struct bpf_uprobe {
loff_t offset;
unsigned long ref_ctr_offset;
u64 cookie;
+ struct uprobe *uprobe;
struct uprobe_consumer consumer;
};

@@ -3178,15 +3179,12 @@ struct bpf_uprobe_multi_run_ctx {
struct bpf_uprobe *uprobe;
};

-static void bpf_uprobe_unregister(struct path *path, struct bpf_uprobe *uprobes,
- u32 cnt)
+static void bpf_uprobe_unregister(struct bpf_uprobe *uprobes, u32 cnt)
{
u32 i;

- for (i = 0; i < cnt; i++) {
- uprobe_unregister(d_real_inode(path->dentry), uprobes[i].offset,
- &uprobes[i].consumer);
- }
+ for (i = 0; i < cnt; i++)
+ uprobe_unregister(uprobes[i].uprobe, &uprobes[i].consumer);
}

static void bpf_uprobe_multi_link_release(struct bpf_link *link)
@@ -3194,7 +3192,7 @@ static void bpf_uprobe_multi_link_release(struct bpf_link *link)
struct bpf_uprobe_multi_link *umulti_link;

umulti_link = container_of(link, struct bpf_uprobe_multi_link, link);
- bpf_uprobe_unregister(&umulti_link->path, umulti_link->uprobes, umulti_link->cnt);
+ bpf_uprobe_unregister(umulti_link->uprobes, umulti_link->cnt);
if (umulti_link->task)
put_task_struct(umulti_link->task);
path_put(&umulti_link->path);
@@ -3480,12 +3478,13 @@ int bpf_uprobe_multi_link_attach(const union bpf_attr *attr, struct bpf_prog *pr
&bpf_uprobe_multi_link_lops, prog);

for (i = 0; i < cnt; i++) {
- err = uprobe_register(d_real_inode(link->path.dentry),
- uprobes[i].offset,
- uprobes[i].ref_ctr_offset,
- &uprobes[i].consumer);
- if (err) {
- bpf_uprobe_unregister(&path, uprobes, i);
+ uprobes[i].uprobe = uprobe_register(d_real_inode(link->path.dentry),
+ uprobes[i].offset,
+ uprobes[i].ref_ctr_offset,
+ &uprobes[i].consumer);
+ if (IS_ERR(uprobes[i].uprobe)) {
+ err = PTR_ERR(uprobes[i].uprobe);
+ bpf_uprobe_unregister(uprobes, i);
goto error_free;
}
}
diff --git a/kernel/trace/trace_uprobe.c b/kernel/trace/trace_uprobe.c
index 1f590f989c1e..52e76a73fa7c 100644
--- a/kernel/trace/trace_uprobe.c
+++ b/kernel/trace/trace_uprobe.c
@@ -58,8 +58,8 @@ struct trace_uprobe {
struct dyn_event devent;
struct uprobe_consumer consumer;
struct path path;
- struct inode *inode;
char *filename;
+ struct uprobe *uprobe;
unsigned long offset;
unsigned long ref_ctr_offset;
unsigned long nhit;
@@ -1084,16 +1084,16 @@ typedef bool (*filter_func_t)(struct uprobe_consumer *self,

static int trace_uprobe_enable(struct trace_uprobe *tu, filter_func_t filter)
{
- int ret;
+ struct inode *inode = d_real_inode(tu->path.dentry);
+ struct uprobe *uprobe;

tu->consumer.filter = filter;
- tu->inode = d_real_inode(tu->path.dentry);
-
- ret = uprobe_register(tu->inode, tu->offset, tu->ref_ctr_offset, &tu->consumer);
- if (ret)
- tu->inode = NULL;
+ uprobe = uprobe_register(inode, tu->offset, tu->ref_ctr_offset, &tu->consumer);
+ if (IS_ERR(uprobe))
+ return PTR_ERR(uprobe);

- return ret;
+ tu->uprobe = uprobe;
+ return 0;
}

static void __probe_event_disable(struct trace_probe *tp)
@@ -1104,11 +1104,11 @@ static void __probe_event_disable(struct trace_probe *tp)
WARN_ON(!uprobe_filter_is_empty(tu->tp.event->filter));

list_for_each_entry(tu, trace_probe_probe_list(tp), tp.list) {
- if (!tu->inode)
+ if (!tu->uprobe)
continue;

- uprobe_unregister(tu->inode, tu->offset, &tu->consumer);
- tu->inode = NULL;
+ uprobe_unregister(tu->uprobe, &tu->consumer);
+ tu->uprobe = NULL;
}
}

@@ -1305,7 +1305,7 @@ static int uprobe_perf_close(struct trace_event_call *call,
return 0;

list_for_each_entry(tu, trace_probe_probe_list(tp), tp.list) {
- ret = uprobe_apply(tu->inode, tu->offset, &tu->consumer, false);
+ ret = uprobe_apply(tu->uprobe, &tu->consumer, false);
if (ret)
break;
}
@@ -1329,7 +1329,7 @@ static int uprobe_perf_open(struct trace_event_call *call,
return 0;

list_for_each_entry(tu, trace_probe_probe_list(tp), tp.list) {
- err = uprobe_apply(tu->inode, tu->offset, &tu->consumer, true);
+ err = uprobe_apply(tu->uprobe, &tu->consumer, true);
if (err) {
uprobe_perf_close(call, event);
break;
--
2.25.1.362.g51ebf55