Messages in this thread | | | Date | Thu, 12 Jan 2023 12:15:59 +0800 | Subject | Re: [PATCH] uprobes: list all active uprobes in the system | From | Longjun Luo <> |
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在 1/12/2023 5:35 AM, Ian Rogers 写道: > On Wed, Jan 11, 2023 at 2:49 AM <luolongjun@huawei.com> wrote: >> From: Longjun Luo <luolongjun@huawei.com> >> >> Since uprobes will replace instructions in the process >> memory, it is necessary to provide one way to list >> all active uprobes. One can access this file through >> /sys/kernel/debug/uprobes/list. >> >> Output looks like this >> ===================== >> inode+offset/ref_ctr_offset 4160760670+0x30a10/0x0 >> ref 1 >> register_rwsem (unlocked) >> consumer_rwsem (unlocked) >> consumers-1 >> handler 0xffffffffc03ee02e(handler) uprobe >> ret_handler 0x0000000000000000( ) >> filter 0xffffffffc03ee010(filter) uprobe >> consumers-2 >> handler 0xffffffffc03e902e(handler_1) uprobe_1 >> ret_handler 0x0000000000000000( ) >> filter 0xffffffffc03e9010(filter_1) uprobe_1 >> >> Signed-off-by: Longjun Luo <luolongjun@huawei.com> >> --- >> kernel/events/uprobes.c | 120 ++++++++++++++++++++++++++++++++++++---- >> 1 file changed, 109 insertions(+), 11 deletions(-) >> >> diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c >> index d9e357b7e17c..2fa9b910abc7 100644 >> --- a/kernel/events/uprobes.c >> +++ b/kernel/events/uprobes.c >> @@ -27,6 +27,9 @@ >> #include <linux/task_work.h> >> #include <linux/shmem_fs.h> >> #include <linux/khugepaged.h> >> +#include <linux/rbtree.h> >> +#include <linux/debugfs.h> >> +#include <linux/kallsyms.h> >> >> #include <linux/uprobes.h> >> >> @@ -40,7 +43,7 @@ static struct rb_root uprobes_tree = RB_ROOT; >> */ >> #define no_uprobe_events() RB_EMPTY_ROOT(&uprobes_tree) >> >> -static DEFINE_SPINLOCK(uprobes_treelock); /* serialize rbtree access */ >> +static DECLARE_RWSEM(uprobes_treelock); /* serialize rbtree access */ >> >> #define UPROBES_HASH_SZ 13 >> /* serialize uprobe->pending_list */ >> @@ -672,9 +675,9 @@ static struct uprobe *find_uprobe(struct inode *inode, loff_t offset) >> { >> struct uprobe *uprobe; >> >> - spin_lock(&uprobes_treelock); >> + down_read(&uprobes_treelock); >> uprobe = __find_uprobe(inode, offset); >> - spin_unlock(&uprobes_treelock); >> + up_read(&uprobes_treelock); >> >> return uprobe; >> } >> @@ -704,9 +707,9 @@ static struct uprobe *insert_uprobe(struct uprobe *uprobe) >> { >> struct uprobe *u; >> >> - spin_lock(&uprobes_treelock); >> + down_write(&uprobes_treelock); >> u = __insert_uprobe(uprobe); >> - spin_unlock(&uprobes_treelock); >> + up_write(&uprobes_treelock); >> >> return u; >> } >> @@ -938,9 +941,9 @@ static void delete_uprobe(struct uprobe *uprobe) >> if (WARN_ON(!uprobe_is_active(uprobe))) >> return; >> >> - spin_lock(&uprobes_treelock); >> + down_write(&uprobes_treelock); >> rb_erase(&uprobe->rb_node, &uprobes_tree); >> - spin_unlock(&uprobes_treelock); >> + up_write(&uprobes_treelock); >> RB_CLEAR_NODE(&uprobe->rb_node); /* for uprobe_is_active() */ >> put_uprobe(uprobe); >> } >> @@ -1301,7 +1304,7 @@ static void build_probe_list(struct inode *inode, >> min = vaddr_to_offset(vma, start); >> max = min + (end - start) - 1; >> >> - spin_lock(&uprobes_treelock); >> + down_read(&uprobes_treelock); >> n = find_node_in_range(inode, min, max); >> if (n) { >> for (t = n; t; t = rb_prev(t)) { >> @@ -1319,7 +1322,7 @@ static void build_probe_list(struct inode *inode, >> get_uprobe(u); >> } >> } >> - spin_unlock(&uprobes_treelock); >> + up_read(&uprobes_treelock); >> } >> >> /* @vma contains reference counter, not the probed instruction. */ >> @@ -1410,9 +1413,9 @@ vma_has_uprobes(struct vm_area_struct *vma, unsigned long start, unsigned long e >> min = vaddr_to_offset(vma, start); >> max = min + (end - start) - 1; >> >> - spin_lock(&uprobes_treelock); >> + down_read(&uprobes_treelock); >> n = find_node_in_range(inode, min, max); >> - spin_unlock(&uprobes_treelock); >> + up_read(&uprobes_treelock); >> >> return !!n; >> } >> @@ -2357,3 +2360,98 @@ void __init uprobes_init(void) >> >> BUG_ON(register_die_notifier(&uprobe_exception_nb)); >> } >> + >> +#ifdef CONFIG_DEBUG_FS >> + >> +static void *uprobe_seq_start(struct seq_file *m, loff_t *pos) >> +{ >> + loff_t num = *pos; >> + struct rb_node *rbp; >> + >> + down_read(&uprobes_treelock); > Is there a missing corresponding up_read? > > Thanks, > Ian This missing corresponding up_read is in the uprobe_seq_stop.
In my understanding, uprobe_seq_start and uprobe_seq_stop is one pair of API.
uprobe_seq_start holds the lock and the uprobe_seq_stop releases it.
I am not sure if it is right.
By the way, may I ask if the community still plan to evolve the uprobe since the uprobe hasn't changed for a long time. >> + for (rbp = rb_first(&uprobes_tree); rbp; rbp = rb_next(rbp)) { >> + if (num-- == 0) >> + return rbp; >> + } >> + >> + return NULL; >> +} >> + >> +static void *uprobe_seq_next(struct seq_file *f, void *v, loff_t *pos) >> +{ >> + ++*pos; >> + return (void *)rb_next(v); >> +} >> + >> +static void uprobe_seq_stop(struct seq_file *f, void *v) >> +{ >> + up_read(&uprobes_treelock); >> +} >> + >> +static int show_uprobe(struct seq_file *m, void *v) >> +{ >> + struct uprobe *uprobe = rb_entry_safe(v, struct uprobe, rb_node); >> + struct uprobe_consumer *con; >> + char *modname, namebuf[KSYM_NAME_LEN]; >> + const char *sym; >> + unsigned int cnt = 1; >> + >> + seq_printf(m, "inode+offset/ref_ctr_offset %lu+0x%llx/0x%llx\n", >> + uprobe->inode->i_ino, uprobe->offset, uprobe->ref_ctr_offset); >> + seq_printf(m, " ref %u\n", >> + refcount_read(&uprobe->ref)); >> + seq_printf(m, " register_rwsem %s\n", >> + rwsem_is_locked(&uprobe->register_rwsem)?"(locked)":"(unlocked)"); >> + seq_printf(m, " consumer_rwsem %s\n", >> + rwsem_is_locked(&uprobe->consumer_rwsem)?"(locked)":"(unlocked)"); >> + >> + /* lock consumer_rwsem when hold uprobes_treelock */ >> + down_read(&uprobe->consumer_rwsem); >> + for (con = uprobe->consumers; con; con = con->next, cnt++) { >> + seq_printf(m, " consumers-%u\n", cnt); >> + >> + modname = NULL; >> + sym = kallsyms_lookup((unsigned long)con->handler, NULL, NULL, >> + &modname, namebuf); >> + seq_printf(m, " handler 0x%px(%s) %s\n", >> + con->handler, (sym ? sym : " "), (modname ? modname : " ")); >> + >> + modname = NULL; >> + sym = kallsyms_lookup((unsigned long)con->ret_handler, NULL, NULL, >> + &modname, namebuf); >> + seq_printf(m, " ret_handler 0x%px(%s) %s\n", >> + con->ret_handler, (sym ? sym : " "), (modname ? modname : " ")); >> + >> + modname = NULL; >> + sym = kallsyms_lookup((unsigned long)con->filter, NULL, NULL, >> + &modname, namebuf); >> + seq_printf(m, " filter 0x%px(%s) %s\n", >> + con->filter, (sym ? sym : " "), (modname ? modname : " ")); >> + } >> + up_read(&uprobe->consumer_rwsem); >> + >> + return 0; >> +} >> + >> +static const struct seq_operations uprobes_sops = { >> + .start = uprobe_seq_start, >> + .next = uprobe_seq_next, >> + .stop = uprobe_seq_stop, >> + .show = show_uprobe, >> +}; >> + >> +DEFINE_SEQ_ATTRIBUTE(uprobes); >> + >> +static int __init debugfs_uprobe_init(void) >> +{ >> + struct dentry *dir; >> + >> + dir = debugfs_create_dir("uprobes", NULL); >> + >> + debugfs_create_file("list", 0400, dir, NULL, &uprobes_fops); >> + >> + return 0; >> +} >> +late_initcall(debugfs_uprobe_init); >> + >> +#endif /* CONFIG_DEBUG_FS */ >> -- >> 2.38.1 >>
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