/* SPDX-License-Identifier: GPL-2.0 */
/*
* Copyright (C) 2017 Steven Rostedt, VMware Inc.
*/
#include <linux/export.h>
#include <linux/linkage.h>
#include <asm/page_types.h>
#include <asm/segment.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 # 1
st 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)
SYM_FUNC_START(ftrace_stub_direct_tramp)
CALL_DEPTH_ACCOUNT
RET
SYM_FUNC_END(ftrace_stub_direct_tramp)
#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:
subl $(PTREGS_SIZE), %esp
movl $0, PT_EBP(%esp)
movl %edx, PT_EDX(%esp)
movl %eax, PT_EAX(%esp)
movl %esp, %eax
call ftrace_return_to_handler
movl %eax, %ecx
movl PT_EAX(%esp), %eax
movl PT_EDX(%esp), %edx
addl $(PTREGS_SIZE), %esp
JMP_NOSPEC ecx
#endif
