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| author |   Peter Zijlstra <peterz@infradead.org> | 2021-05-25 09:25:19 +0200 |
|---|---|---|
| committer | Peter Zijlstra <peterz@infradead.org> | 2021-06-01 16:00:08 +0200 |
| commit | ec6aba3d2be1ed75b3f4c894bb64a36d40db1f55 (patch) | |
| tree | 0fd56814090efcd59ce2f2b29906043853764b23 /Documentation/trace | |
| parent | uprobes: Update uprobe_write_opcode() kernel-doc comment (diff) | |
| download | linux-dev-ec6aba3d2be1ed75b3f4c894bb64a36d40db1f55.tar.xz linux-dev-ec6aba3d2be1ed75b3f4c894bb64a36d40db1f55.zip | |
kprobes: Remove kprobe::fault_handler
The reason for kprobe::fault_handler(), as given by their comment:
* We come here because instructions in the pre/post
* handler caused the page_fault, this could happen
* if handler tries to access user space by
* copy_from_user(), get_user() etc. Let the
* user-specified handler try to fix it first.
Is just plain bad. Those other handlers are ran from non-preemptible
context and had better use _nofault() functions. Also, there is no
upstream usage of this.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Link: https://lore.kernel.org/r/20210525073213.561116662@infradead.org
Diffstat (limited to 'Documentation/trace')
| -rw-r--r-- | Documentation/trace/kprobes.rst | 24 |
1 files changed, 5 insertions, 19 deletions
diff --git a/Documentation/trace/kprobes.rst b/Documentation/trace/kprobes.rst index b757b6dfd3d4..998149ce2fd9 100644 --- a/Documentation/trace/kprobes.rst +++ b/Documentation/trace/kprobes.rst @@ -362,14 +362,11 @@ register_kprobe #include <linux/kprobes.h> int register_kprobe(struct kprobe *kp); -Sets a breakpoint at the address kp->addr. When the breakpoint is -hit, Kprobes calls kp->pre_handler. After the probed instruction -is single-stepped, Kprobe calls kp->post_handler. If a fault -occurs during execution of kp->pre_handler or kp->post_handler, -or during single-stepping of the probed instruction, Kprobes calls -kp->fault_handler. Any or all handlers can be NULL. If kp->flags -is set KPROBE_FLAG_DISABLED, that kp will be registered but disabled, -so, its handlers aren't hit until calling enable_kprobe(kp). +Sets a breakpoint at the address kp->addr. When the breakpoint is hit, Kprobes +calls kp->pre_handler. After the probed instruction is single-stepped, Kprobe +calls kp->post_handler. Any or all handlers can be NULL. If kp->flags is set +KPROBE_FLAG_DISABLED, that kp will be registered but disabled, so, its handlers +aren't hit until calling enable_kprobe(kp). .. note:: @@ -415,17 +412,6 @@ User's post-handler (kp->post_handler):: p and regs are as described for the pre_handler. flags always seems to be zero. -User's fault-handler (kp->fault_handler):: - - #include <linux/kprobes.h> - #include <linux/ptrace.h> - int fault_handler(struct kprobe *p, struct pt_regs *regs, int trapnr); - -p and regs are as described for the pre_handler. trapnr is the -architecture-specific trap number associated with the fault (e.g., -on i386, 13 for a general protection fault or 14 for a page fault). -Returns 1 if it successfully handled the exception. - register_kretprobe ------------------ |