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From: Jiri Olsa <jolsa@redhat.com>
To: Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Andrii Nakryiko <andriin@fb.com>,
"Steven Rostedt (VMware)" <rostedt@goodmis.org>
Cc: netdev@vger.kernel.org, bpf@vger.kernel.org,
Martin KaFai Lau <kafai@fb.com>, Song Liu <songliubraving@fb.com>,
Yonghong Song <yhs@fb.com>,
John Fastabend <john.fastabend@gmail.com>,
KP Singh <kpsingh@chromium.org>, Daniel Xu <dxu@dxuuu.xyz>,
Viktor Malik <vmalik@redhat.com>
Subject: [PATCH bpf-next v4 02/27] x86/ftrace: Remove fault protection code in prepare_ftrace_return
Date: Thu, 26 Aug 2021 21:38:57 +0200 [thread overview]
Message-ID: <20210826193922.66204-3-jolsa@kernel.org> (raw)
In-Reply-To: <20210826193922.66204-1-jolsa@kernel.org>
From: "Steven Rostedt (VMware)" <rostedt@goodmis.org>
Removing the fault protection code when writing return_hooker
to stack. As Steven noted:
> That protection was there from the beginning due to being "paranoid",
> considering ftrace was bricking network cards. But that protection
> would not have even protected against that.
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
---
arch/x86/kernel/ftrace.c | 38 +++-----------------------------------
1 file changed, 3 insertions(+), 35 deletions(-)
diff --git a/arch/x86/kernel/ftrace.c b/arch/x86/kernel/ftrace.c
index 1b3ce3b4a2a2..c555624da989 100644
--- a/arch/x86/kernel/ftrace.c
+++ b/arch/x86/kernel/ftrace.c
@@ -625,12 +625,10 @@ int ftrace_disable_ftrace_graph_caller(void)
* Hook the return address and push it in the stack of return addrs
* in current thread info.
*/
-void prepare_ftrace_return(unsigned long self_addr, unsigned long *parent,
+void prepare_ftrace_return(unsigned long ip, unsigned long *parent,
unsigned long frame_pointer)
{
unsigned long return_hooker = (unsigned long)&return_to_handler;
- unsigned long old;
- int faulted;
/*
* When resuming from suspend-to-ram, this function can be indirectly
@@ -650,37 +648,7 @@ void prepare_ftrace_return(unsigned long self_addr, unsigned long *parent,
if (unlikely(atomic_read(¤t->tracing_graph_pause)))
return;
- /*
- * Protect against fault, even if it shouldn't
- * happen. This tool is too much intrusive to
- * ignore such a protection.
- */
- asm volatile(
- "1: " _ASM_MOV " (%[parent]), %[old]\n"
- "2: " _ASM_MOV " %[return_hooker], (%[parent])\n"
- " movl $0, %[faulted]\n"
- "3:\n"
-
- ".section .fixup, \"ax\"\n"
- "4: movl $1, %[faulted]\n"
- " jmp 3b\n"
- ".previous\n"
-
- _ASM_EXTABLE(1b, 4b)
- _ASM_EXTABLE(2b, 4b)
-
- : [old] "=&r" (old), [faulted] "=r" (faulted)
- : [parent] "r" (parent), [return_hooker] "r" (return_hooker)
- : "memory"
- );
-
- if (unlikely(faulted)) {
- ftrace_graph_stop();
- WARN_ON(1);
- return;
- }
-
- if (function_graph_enter(old, self_addr, frame_pointer, parent))
- *parent = old;
+ if (!function_graph_enter(*parent, ip, frame_pointer, parent))
+ *parent = return_hooker;
}
#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
--
2.31.1
next prev parent reply other threads:[~2021-08-26 19:39 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-08-26 19:38 [PATCH bpf-next v4 00/27] x86/ftrace/bpf: Add batch support for direct/tracing attach Jiri Olsa
2021-08-26 19:38 ` [PATCH bpf-next v4 01/27] x86/ftrace: Remove extra orig rax move Jiri Olsa
2021-08-26 19:38 ` Jiri Olsa [this message]
2021-08-26 19:38 ` [PATCH bpf-next v4 03/27] x86/ftrace: Make function graph use ftrace directly Jiri Olsa
2021-08-26 19:38 ` [PATCH bpf-next v4 04/27] tracing: Add trampoline/graph selftest Jiri Olsa
2021-08-26 19:39 ` [PATCH bpf-next v4 05/27] ftrace: Add ftrace_add_rec_direct function Jiri Olsa
2021-08-26 19:39 ` [PATCH bpf-next v4 06/27] ftrace: Add multi direct register/unregister interface Jiri Olsa
2021-08-26 19:39 ` [PATCH bpf-next v4 07/27] ftrace: Add multi direct modify interface Jiri Olsa
2021-08-26 19:39 ` [PATCH bpf-next v4 08/27] ftrace/samples: Add multi direct interface test module Jiri Olsa
2021-08-26 19:39 ` [PATCH bpf-next v4 09/27] bpf: Add support to load multi func tracing program Jiri Olsa
2021-08-31 23:17 ` Andrii Nakryiko
2021-09-01 11:32 ` Jiri Olsa
2021-08-26 19:39 ` [PATCH bpf-next v4 10/27] bpf: Add struct bpf_tramp_node layer Jiri Olsa
2021-08-26 19:39 ` [PATCH bpf-next v4 11/27] bpf: Factor out bpf_trampoline_init function Jiri Olsa
2021-08-26 19:39 ` [PATCH bpf-next v4 12/27] bpf: Factor out __bpf_trampoline_lookup function Jiri Olsa
2021-08-26 19:39 ` [PATCH bpf-next v4 13/27] bpf: Factor out __bpf_trampoline_put function Jiri Olsa
2021-08-26 19:39 ` [PATCH bpf-next v4 14/27] bpf: Change bpf_trampoline_get to return error pointer Jiri Olsa
2021-08-26 19:39 ` [PATCH bpf-next v4 15/27] bpf, x64: Allow to use caller address from stack Jiri Olsa
2021-08-26 19:39 ` [PATCH bpf-next v4 16/27] bpf: Add bpf_trampoline_multi_get/put functions Jiri Olsa
2021-08-26 19:39 ` [PATCH bpf-next v4 17/27] bpf: Add multi trampoline attach support Jiri Olsa
2021-08-31 23:36 ` Andrii Nakryiko
2021-09-01 0:02 ` Andrii Nakryiko
2021-09-01 11:39 ` Jiri Olsa
2021-08-26 19:39 ` [PATCH bpf-next v4 18/27] bpf, x64: Store properly return value for trampoline with multi func programs Jiri Olsa
2021-08-31 23:51 ` Andrii Nakryiko
2021-09-01 15:15 ` Jiri Olsa
2021-09-02 3:56 ` Andrii Nakryiko
2021-09-02 12:57 ` Jiri Olsa
2021-09-02 16:54 ` Andrii Nakryiko
2021-09-02 21:55 ` Alexei Starovoitov
2021-09-03 9:50 ` Jiri Olsa
2021-08-26 19:39 ` [PATCH bpf-next v4 19/27] bpf: Attach multi trampoline with ftrace_ops Jiri Olsa
2021-08-26 19:39 ` [PATCH bpf-next v4 20/27] libbpf: Add btf__find_by_glob_kind function Jiri Olsa
2021-09-01 0:10 ` Andrii Nakryiko
2021-09-01 11:33 ` Jiri Olsa
2021-08-26 19:39 ` [PATCH bpf-next v4 21/27] libbpf: Add support to link multi func tracing program Jiri Olsa
2021-08-26 19:39 ` [PATCH bpf-next v4 22/27] selftests/bpf: Add fentry multi func test Jiri Olsa
2021-08-26 19:39 ` [PATCH bpf-next v4 23/27] selftests/bpf: Add fexit " Jiri Olsa
2021-08-26 19:39 ` [PATCH bpf-next v4 24/27] selftests/bpf: Add fentry/fexit " Jiri Olsa
2021-08-26 19:39 ` [PATCH bpf-next v4 25/27] selftests/bpf: Add mixed " Jiri Olsa
2021-08-26 19:39 ` [PATCH bpf-next v4 26/27] selftests/bpf: Add attach " Jiri Olsa
2021-08-26 19:39 ` [PATCH bpf-next v4 27/27] selftests/bpf: Add ret_mod " Jiri Olsa
2021-08-29 17:04 ` [PATCH bpf-next v4 00/27] x86/ftrace/bpf: Add batch support for direct/tracing attach Alexei Starovoitov
2021-08-30 8:02 ` Jiri Olsa
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