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Diffstat (limited to 'arch/x86/kernel/ftrace_32.S')
| -rw-r--r-- | arch/x86/kernel/ftrace_32.S | 193 |
1 files changed, 193 insertions, 0 deletions
diff --git a/arch/x86/kernel/ftrace_32.S b/arch/x86/kernel/ftrace_32.S new file mode 100644 index 000000000..a0ed0e4a2 --- /dev/null +++ b/arch/x86/kernel/ftrace_32.S @@ -0,0 +1,193 @@ +/* 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 |