linux-stable/arch/x86/kernel/ftrace_32.S
Borislav Petkov 0f42c1ad44 x86/ftrace: Get rid of function_hook
History lesson courtesy of Steve:

"When ftrace first was introduced to the kernel, it used gcc's
mcount profiling mechanism. The mcount mechanism would add a call to
"mcount" at the start of every function but after the stack frame was
set up. Later, in gcc 4.6, gcc introduced -mfentry, that would create a
call to "__fentry__" instead of "mcount", before the stack frame was
set up. In order to handle both cases, ftrace defined a macro
"function_hook" that would be either "mcount" or "__fentry__" depending
on which one was being used.

The Linux kernel no longer supports the "mcount" method, thus there's
no reason to keep the "function_hook" define around. Simply use
"__fentry__", as there is no ambiguity to the name anymore."

Drop it everywhere.

Signed-off-by: Borislav Petkov <bp@suse.de>
Acked-by: Jiri Slaby <jslaby@suse.cz>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: linux-doc@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: "Steven Rostedt (VMware)" <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: x86@kernel.org
Link: http://lkml.kernel.org/r/20191018124800.0a7006bb@gandalf.local.home
2019-10-25 10:52:22 +02:00

193 lines
3.9 KiB
ArmAsm

/* SPDX-License-Identifier: GPL-2.0 */
/*
* Copyright (C) 2017 Steven Rostedt, VMware Inc.
*/
#include <linux/linkage.h>
#include <asm/page_types.h>
#include <asm/segment.h>
#include <asm/export.h>
#include <asm/ftrace.h>
#include <asm/nospec-branch.h>
#include <asm/frame.h>
#include <asm/asm-offsets.h>
#ifdef CONFIG_FRAME_POINTER
# define MCOUNT_FRAME 1 /* using frame = true */
#else
# define MCOUNT_FRAME 0 /* using frame = false */
#endif
SYM_FUNC_START(__fentry__)
ret
SYM_FUNC_END(__fentry__)
EXPORT_SYMBOL(__fentry__)
SYM_CODE_START(ftrace_caller)
#ifdef CONFIG_FRAME_POINTER
/*
* Frame pointers are of ip followed by bp.
* Since fentry is an immediate jump, we are left with
* parent-ip, function-ip. We need to add a frame with
* parent-ip followed by ebp.
*/
pushl 4(%esp) /* parent ip */
pushl %ebp
movl %esp, %ebp
pushl 2*4(%esp) /* function ip */
/* For mcount, the function ip is directly above */
pushl %ebp
movl %esp, %ebp
#endif
pushl %eax
pushl %ecx
pushl %edx
pushl $0 /* Pass NULL as regs pointer */
#ifdef CONFIG_FRAME_POINTER
/* Load parent ebp into edx */
movl 4*4(%esp), %edx
#else
/* There's no frame pointer, load the appropriate stack addr instead */
lea 4*4(%esp), %edx
#endif
movl (MCOUNT_FRAME+4)*4(%esp), %eax /* load the rip */
/* Get the parent ip */
movl 4(%edx), %edx /* edx has ebp */
movl function_trace_op, %ecx
subl $MCOUNT_INSN_SIZE, %eax
.globl ftrace_call
ftrace_call:
call ftrace_stub
addl $4, %esp /* skip NULL pointer */
popl %edx
popl %ecx
popl %eax
#ifdef CONFIG_FRAME_POINTER
popl %ebp
addl $4,%esp /* skip function ip */
popl %ebp /* this is the orig bp */
addl $4, %esp /* skip parent ip */
#endif
.Lftrace_ret:
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
.globl ftrace_graph_call
ftrace_graph_call:
jmp ftrace_stub
#endif
/* This is weak to keep gas from relaxing the jumps */
SYM_INNER_LABEL_ALIGN(ftrace_stub, SYM_L_WEAK)
ret
SYM_CODE_END(ftrace_caller)
SYM_CODE_START(ftrace_regs_caller)
/*
* We're here from an mcount/fentry CALL, and the stack frame looks like:
*
* <previous context>
* RET-IP
*
* The purpose of this function is to call out in an emulated INT3
* environment with a stack frame like:
*
* <previous context>
* gap / RET-IP
* gap
* gap
* gap
* pt_regs
*
* We do _NOT_ restore: ss, flags, cs, gs, fs, es, ds
*/
subl $3*4, %esp # RET-IP + 3 gaps
pushl %ss # ss
pushl %esp # points at ss
addl $5*4, (%esp) # make it point at <previous context>
pushfl # flags
pushl $__KERNEL_CS # cs
pushl 7*4(%esp) # ip <- RET-IP
pushl $0 # orig_eax
pushl %gs
pushl %fs
pushl %es
pushl %ds
pushl %eax
pushl %ebp
pushl %edi
pushl %esi
pushl %edx
pushl %ecx
pushl %ebx
ENCODE_FRAME_POINTER
movl PT_EIP(%esp), %eax # 1st argument: IP
subl $MCOUNT_INSN_SIZE, %eax
movl 21*4(%esp), %edx # 2nd argument: parent ip
movl function_trace_op, %ecx # 3rd argument: ftrace_pos
pushl %esp # 4th argument: pt_regs
SYM_INNER_LABEL(ftrace_regs_call, SYM_L_GLOBAL)
call ftrace_stub
addl $4, %esp # skip 4th argument
/* place IP below the new SP */
movl PT_OLDESP(%esp), %eax
movl PT_EIP(%esp), %ecx
movl %ecx, -4(%eax)
/* place EAX below that */
movl PT_EAX(%esp), %ecx
movl %ecx, -8(%eax)
popl %ebx
popl %ecx
popl %edx
popl %esi
popl %edi
popl %ebp
lea -8(%eax), %esp
popl %eax
jmp .Lftrace_ret
SYM_CODE_END(ftrace_regs_caller)
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
SYM_CODE_START(ftrace_graph_caller)
pushl %eax
pushl %ecx
pushl %edx
movl 3*4(%esp), %eax
/* Even with frame pointers, fentry doesn't have one here */
lea 4*4(%esp), %edx
movl $0, %ecx
subl $MCOUNT_INSN_SIZE, %eax
call prepare_ftrace_return
popl %edx
popl %ecx
popl %eax
ret
SYM_CODE_END(ftrace_graph_caller)
.globl return_to_handler
return_to_handler:
pushl %eax
pushl %edx
movl $0, %eax
call ftrace_return_to_handler
movl %eax, %ecx
popl %edx
popl %eax
JMP_NOSPEC %ecx
#endif