From: Steven Rostedt <rostedt@goodmis.org>
To: linux-kernel@vger.kernel.org
Cc: Ingo Molnar <mingo@kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
Peter Zijlstra <peterz@infradead.org>
Subject: [for-next][PATCH 04/18] x86/ftrace: Do not jump to direct code in created trampolines
Date: Thu, 02 Jul 2020 17:58:16 -0400 [thread overview]
Message-ID: <20200702215832.049969400@goodmis.org> (raw)
In-Reply-To: 20200702215812.428188663@goodmis.org
From: "Steven Rostedt (VMware)" <rostedt@goodmis.org>
When creating a trampoline based on the ftrace_regs_caller code, nop out the
jnz test that would jmup to the code that would return to a direct caller
(stored in the ORIG_RAX field) and not back to the function that called it.
Link: http://lkml.kernel.org/r/20200422162750.638839749@goodmis.org
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
---
arch/x86/kernel/ftrace.c | 15 +++++++++++++++
arch/x86/kernel/ftrace_64.S | 1 +
2 files changed, 16 insertions(+)
diff --git a/arch/x86/kernel/ftrace.c b/arch/x86/kernel/ftrace.c
index d1a0190fef5b..7edbd5ee5ed4 100644
--- a/arch/x86/kernel/ftrace.c
+++ b/arch/x86/kernel/ftrace.c
@@ -286,6 +286,7 @@ extern void ftrace_regs_caller_ret(void);
extern void ftrace_caller_end(void);
extern void ftrace_caller_op_ptr(void);
extern void ftrace_regs_caller_op_ptr(void);
+extern void ftrace_regs_caller_jmp(void);
/* movq function_trace_op(%rip), %rdx */
/* 0x48 0x8b 0x15 <offset-to-ftrace_trace_op (4 bytes)> */
@@ -316,6 +317,7 @@ create_trampoline(struct ftrace_ops *ops, unsigned int *tramp_size)
unsigned long end_offset;
unsigned long op_offset;
unsigned long call_offset;
+ unsigned long jmp_offset;
unsigned long offset;
unsigned long npages;
unsigned long size;
@@ -333,11 +335,13 @@ create_trampoline(struct ftrace_ops *ops, unsigned int *tramp_size)
end_offset = (unsigned long)ftrace_regs_caller_end;
op_offset = (unsigned long)ftrace_regs_caller_op_ptr;
call_offset = (unsigned long)ftrace_regs_call;
+ jmp_offset = (unsigned long)ftrace_regs_caller_jmp;
} else {
start_offset = (unsigned long)ftrace_caller;
end_offset = (unsigned long)ftrace_caller_end;
op_offset = (unsigned long)ftrace_caller_op_ptr;
call_offset = (unsigned long)ftrace_call;
+ jmp_offset = 0;
}
size = end_offset - start_offset;
@@ -367,6 +371,17 @@ create_trampoline(struct ftrace_ops *ops, unsigned int *tramp_size)
if (WARN_ON(ret < 0))
goto fail;
+ /* No need to test direct calls on created trampolines */
+ if (ops->flags & FTRACE_OPS_FL_SAVE_REGS) {
+ /* NOP the jnz 1f; but make sure it's a 2 byte jnz */
+ ip = trampoline + (jmp_offset - start_offset);
+ if (WARN_ON(*(char *)ip != 0x75))
+ goto fail;
+ ret = copy_from_kernel_nofault(ip, ideal_nops[2], 2);
+ if (ret < 0)
+ goto fail;
+ }
+
/*
* The address of the ftrace_ops that is used for this trampoline
* is stored at the end of the trampoline. This will be used to
diff --git a/arch/x86/kernel/ftrace_64.S b/arch/x86/kernel/ftrace_64.S
index 43cf9a2b52c7..ac3d5f22fe64 100644
--- a/arch/x86/kernel/ftrace_64.S
+++ b/arch/x86/kernel/ftrace_64.S
@@ -241,6 +241,7 @@ SYM_INNER_LABEL(ftrace_regs_call, SYM_L_GLOBAL)
*/
movq ORIG_RAX(%rsp), %rax
testq %rax, %rax
+SYM_INNER_LABEL(ftrace_regs_caller_jmp, SYM_L_GLOBAL)
jnz 1f
restore_mcount_regs
--
2.26.2
next prev parent reply other threads:[~2020-07-02 21:59 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-02 21:58 [for-next][PATCH 00/18] tracing: Updatse for 5.9 Steven Rostedt
2020-07-02 21:58 ` [for-next][PATCH 01/18] tracing: Only allow trace_array_printk() to be used by instances Steven Rostedt
2020-07-02 21:58 ` [for-next][PATCH 02/18] x86/ftrace: Make non direct case the default in ftrace_regs_caller Steven Rostedt
2020-07-02 21:58 ` [for-next][PATCH 03/18] x86/ftrace: Only have the builtin ftrace_regs_caller call direct hooks Steven Rostedt
2020-07-02 21:58 ` Steven Rostedt [this message]
2020-07-03 8:10 ` [for-next][PATCH 04/18] x86/ftrace: Do not jump to direct code in created trampolines Peter Zijlstra
2020-07-14 3:24 ` Steven Rostedt
2020-07-02 21:58 ` [for-next][PATCH 05/18] tracing: not necessary to undefine DEFINE_EVENT again Steven Rostedt
2020-07-02 21:58 ` [for-next][PATCH 06/18] tracing: not necessary re-define DEFINE_EVENT_PRINT Steven Rostedt
2020-07-02 21:58 ` [for-next][PATCH 07/18] tracing: define DEFINE_EVENT_PRINT not related to DEFINE_EVENT Steven Rostedt
2020-07-02 21:58 ` [for-next][PATCH 08/18] tracing: not necessary to define DEFINE_EVENT_PRINT to be empty again Steven Rostedt
2020-07-02 21:58 ` [for-next][PATCH 09/18] tracing: Move pipe reference to trace array instead of current_tracer Steven Rostedt
2020-07-31 19:33 ` dann frazier
2020-07-31 21:16 ` Steven Rostedt
2020-07-31 21:17 ` dann frazier
2020-07-02 21:58 ` [for-next][PATCH 10/18] ring-buffer: Have nested events still record running time stamp Steven Rostedt
2020-07-02 21:58 ` [for-next][PATCH 11/18] ring-buffer: Incorporate absolute timestamp into add_timestamp logic Steven Rostedt
2020-07-02 21:58 ` [for-next][PATCH 12/18] ring-buffer: Add rb_time_t 64 bit operations for speeding up 32 bit Steven Rostedt
2020-07-02 21:58 ` [for-next][PATCH 13/18] ring-buffer: speed up buffer resets by avoiding synchronize_rcu for each CPU Steven Rostedt
2020-07-02 21:58 ` [for-next][PATCH 14/18] ring-buffer: Mark the !tail (crossing a page) as unlikely Steven Rostedt
2020-07-02 21:58 ` [for-next][PATCH 15/18] ring-buffer: Consolidate add_timestamp to remove some branches Steven Rostedt
2020-07-02 21:58 ` [for-next][PATCH 16/18] ring-buffer: Move the add_timestamp into its own function Steven Rostedt
2020-07-02 21:58 ` [for-next][PATCH 17/18] ring-buffer: Call trace_clock_local() directly for RETPOLINE kernels Steven Rostedt
2020-07-02 21:58 ` [for-next][PATCH 18/18] ring-buffer: Do not trigger a WARN if clock going backwards is detected Steven Rostedt
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