mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-08-26 02:39:48 +00:00
x86/ftrace: Fix ORC unwinding from ftrace handlers
Steven Rostedt discovered that the ftrace stack tracer is broken when it's used with the ORC unwinder. The problem is that objtool is instructed by the Makefile to ignore the ftrace_64.S code, so it doesn't generate any ORC data for it. Fix it by making the asm code objtool-friendly: - Objtool doesn't like the fact that save_mcount_regs pushes RBP at the beginning, but it's never restored (directly, at least). So just skip the original RBP push, which is only needed for frame pointers anyway. - Annotate some functions as normal callable functions with ENTRY/ENDPROC. - Add an empty unwind hint to return_to_handler(). The return address isn't on the stack, so there's nothing ORC can do there. It will just punt in the unlikely case it tries to unwind from that code. With all that fixed, remove the OBJECT_FILES_NON_STANDARD Makefile annotation so objtool can read the file. Link: http://lkml.kernel.org/r/20180123040746.ih4ep3tk4pbjvg7c@treble Reported-by: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
This commit is contained in:
parent
0c5b9b5d9a
commit
e2ac83d74a
2 changed files with 19 additions and 10 deletions
|
@ -29,10 +29,13 @@ KASAN_SANITIZE_stacktrace.o := n
|
|||
KASAN_SANITIZE_paravirt.o := n
|
||||
|
||||
OBJECT_FILES_NON_STANDARD_relocate_kernel_$(BITS).o := y
|
||||
OBJECT_FILES_NON_STANDARD_ftrace_$(BITS).o := y
|
||||
OBJECT_FILES_NON_STANDARD_test_nx.o := y
|
||||
OBJECT_FILES_NON_STANDARD_paravirt_patch_$(BITS).o := y
|
||||
|
||||
ifdef CONFIG_FRAME_POINTER
|
||||
OBJECT_FILES_NON_STANDARD_ftrace_$(BITS).o := y
|
||||
endif
|
||||
|
||||
# If instrumentation of this dir is enabled, boot hangs during first second.
|
||||
# Probably could be more selective here, but note that files related to irqs,
|
||||
# boot, dumpstack/stacktrace, etc are either non-interesting or can lead to
|
||||
|
|
|
@ -8,6 +8,7 @@
|
|||
#include <asm/ftrace.h>
|
||||
#include <asm/export.h>
|
||||
#include <asm/nospec-branch.h>
|
||||
#include <asm/unwind_hints.h>
|
||||
|
||||
.code64
|
||||
.section .entry.text, "ax"
|
||||
|
@ -20,7 +21,6 @@ EXPORT_SYMBOL(__fentry__)
|
|||
EXPORT_SYMBOL(mcount)
|
||||
#endif
|
||||
|
||||
/* All cases save the original rbp (8 bytes) */
|
||||
#ifdef CONFIG_FRAME_POINTER
|
||||
# ifdef CC_USING_FENTRY
|
||||
/* Save parent and function stack frames (rip and rbp) */
|
||||
|
@ -31,7 +31,7 @@ EXPORT_SYMBOL(mcount)
|
|||
# endif
|
||||
#else
|
||||
/* No need to save a stack frame */
|
||||
# define MCOUNT_FRAME_SIZE 8
|
||||
# define MCOUNT_FRAME_SIZE 0
|
||||
#endif /* CONFIG_FRAME_POINTER */
|
||||
|
||||
/* Size of stack used to save mcount regs in save_mcount_regs */
|
||||
|
@ -64,10 +64,10 @@ EXPORT_SYMBOL(mcount)
|
|||
*/
|
||||
.macro save_mcount_regs added=0
|
||||
|
||||
/* Always save the original rbp */
|
||||
#ifdef CONFIG_FRAME_POINTER
|
||||
/* Save the original rbp */
|
||||
pushq %rbp
|
||||
|
||||
#ifdef CONFIG_FRAME_POINTER
|
||||
/*
|
||||
* Stack traces will stop at the ftrace trampoline if the frame pointer
|
||||
* is not set up properly. If fentry is used, we need to save a frame
|
||||
|
@ -105,7 +105,11 @@ EXPORT_SYMBOL(mcount)
|
|||
* Save the original RBP. Even though the mcount ABI does not
|
||||
* require this, it helps out callers.
|
||||
*/
|
||||
#ifdef CONFIG_FRAME_POINTER
|
||||
movq MCOUNT_REG_SIZE-8(%rsp), %rdx
|
||||
#else
|
||||
movq %rbp, %rdx
|
||||
#endif
|
||||
movq %rdx, RBP(%rsp)
|
||||
|
||||
/* Copy the parent address into %rsi (second parameter) */
|
||||
|
@ -148,7 +152,7 @@ EXPORT_SYMBOL(mcount)
|
|||
|
||||
ENTRY(function_hook)
|
||||
retq
|
||||
END(function_hook)
|
||||
ENDPROC(function_hook)
|
||||
|
||||
ENTRY(ftrace_caller)
|
||||
/* save_mcount_regs fills in first two parameters */
|
||||
|
@ -184,7 +188,7 @@ GLOBAL(ftrace_graph_call)
|
|||
/* This is weak to keep gas from relaxing the jumps */
|
||||
WEAK(ftrace_stub)
|
||||
retq
|
||||
END(ftrace_caller)
|
||||
ENDPROC(ftrace_caller)
|
||||
|
||||
ENTRY(ftrace_regs_caller)
|
||||
/* Save the current flags before any operations that can change them */
|
||||
|
@ -255,7 +259,7 @@ GLOBAL(ftrace_regs_caller_end)
|
|||
|
||||
jmp ftrace_epilogue
|
||||
|
||||
END(ftrace_regs_caller)
|
||||
ENDPROC(ftrace_regs_caller)
|
||||
|
||||
|
||||
#else /* ! CONFIG_DYNAMIC_FTRACE */
|
||||
|
@ -313,9 +317,10 @@ ENTRY(ftrace_graph_caller)
|
|||
restore_mcount_regs
|
||||
|
||||
retq
|
||||
END(ftrace_graph_caller)
|
||||
ENDPROC(ftrace_graph_caller)
|
||||
|
||||
GLOBAL(return_to_handler)
|
||||
ENTRY(return_to_handler)
|
||||
UNWIND_HINT_EMPTY
|
||||
subq $24, %rsp
|
||||
|
||||
/* Save the return values */
|
||||
|
@ -330,4 +335,5 @@ GLOBAL(return_to_handler)
|
|||
movq (%rsp), %rax
|
||||
addq $24, %rsp
|
||||
JMP_NOSPEC %rdi
|
||||
END(return_to_handler)
|
||||
#endif
|
||||
|
|
Loading…
Reference in a new issue