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Diffstat (limited to '')
| -rw-r--r-- | arch/x86/kernel/ftrace_32.S | 250 |
1 files changed, 250 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..83f18e829 --- /dev/null +++ b/arch/x86/kernel/ftrace_32.S @@ -0,0 +1,250 @@ +/* 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> + +#ifdef CC_USING_FENTRY +# define function_hook __fentry__ +EXPORT_SYMBOL(__fentry__) +#else +# define function_hook mcount +EXPORT_SYMBOL(mcount) +#endif + +#ifdef CONFIG_DYNAMIC_FTRACE + +/* mcount uses a frame pointer even if CONFIG_FRAME_POINTER is not set */ +#if !defined(CC_USING_FENTRY) || defined(CONFIG_FRAME_POINTER) +# define USING_FRAME_POINTER +#endif + +#ifdef USING_FRAME_POINTER +# define MCOUNT_FRAME 1 /* using frame = true */ +#else +# define MCOUNT_FRAME 0 /* using frame = false */ +#endif + +ENTRY(function_hook) + ret +END(function_hook) + +ENTRY(ftrace_caller) + +#ifdef USING_FRAME_POINTER +# ifdef CC_USING_FENTRY + /* + * 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 */ +# endif + /* 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 USING_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 USING_FRAME_POINTER + popl %ebp +# ifdef CC_USING_FENTRY + addl $4,%esp /* skip function ip */ + popl %ebp /* this is the orig bp */ + addl $4, %esp /* skip parent ip */ +# endif +#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 */ +WEAK(ftrace_stub) + ret +END(ftrace_caller) + +ENTRY(ftrace_regs_caller) + /* + * i386 does not save SS and ESP when coming from kernel. + * Instead, to get sp, ®s->sp is used (see ptrace.h). + * Unfortunately, that means eflags must be at the same location + * as the current return ip is. We move the return ip into the + * regs->ip location, and move flags into the return ip location. + */ + pushl $__KERNEL_CS + pushl 4(%esp) /* Save the return ip */ + pushl $0 /* Load 0 into orig_ax */ + pushl %gs + pushl %fs + pushl %es + pushl %ds + pushl %eax + + /* Get flags and place them into the return ip slot */ + pushf + popl %eax + movl %eax, 8*4(%esp) + + pushl %ebp + pushl %edi + pushl %esi + pushl %edx + pushl %ecx + pushl %ebx + + ENCODE_FRAME_POINTER + + movl 12*4(%esp), %eax /* Load ip (1st parameter) */ + subl $MCOUNT_INSN_SIZE, %eax /* Adjust ip */ +#ifdef CC_USING_FENTRY + movl 15*4(%esp), %edx /* Load parent ip (2nd parameter) */ +#else + movl 0x4(%ebp), %edx /* Load parent ip (2nd parameter) */ +#endif + movl function_trace_op, %ecx /* Save ftrace_pos in 3rd parameter */ + pushl %esp /* Save pt_regs as 4th parameter */ + +GLOBAL(ftrace_regs_call) + call ftrace_stub + + addl $4, %esp /* Skip pt_regs */ + + /* restore flags */ + push 14*4(%esp) + popf + + /* Move return ip back to its original location */ + movl 12*4(%esp), %eax + movl %eax, 14*4(%esp) + + popl %ebx + popl %ecx + popl %edx + popl %esi + popl %edi + popl %ebp + popl %eax + popl %ds + popl %es + popl %fs + popl %gs + + /* use lea to not affect flags */ + lea 3*4(%esp), %esp /* Skip orig_ax, ip and cs */ + + jmp .Lftrace_ret +#else /* ! CONFIG_DYNAMIC_FTRACE */ + +ENTRY(function_hook) + cmpl $__PAGE_OFFSET, %esp + jb ftrace_stub /* Paging not enabled yet? */ + + cmpl $ftrace_stub, ftrace_trace_function + jnz .Ltrace +#ifdef CONFIG_FUNCTION_GRAPH_TRACER + cmpl $ftrace_stub, ftrace_graph_return + jnz ftrace_graph_caller + + cmpl $ftrace_graph_entry_stub, ftrace_graph_entry + jnz ftrace_graph_caller +#endif +.globl ftrace_stub +ftrace_stub: + ret + + /* taken from glibc */ +.Ltrace: + pushl %eax + pushl %ecx + pushl %edx + movl 0xc(%esp), %eax + movl 0x4(%ebp), %edx + subl $MCOUNT_INSN_SIZE, %eax + + movl ftrace_trace_function, %ecx + CALL_NOSPEC %ecx + + popl %edx + popl %ecx + popl %eax + jmp ftrace_stub +END(function_hook) +#endif /* CONFIG_DYNAMIC_FTRACE */ + +#ifdef CONFIG_FUNCTION_GRAPH_TRACER +ENTRY(ftrace_graph_caller) + pushl %eax + pushl %ecx + pushl %edx + movl 3*4(%esp), %eax + /* Even with frame pointers, fentry doesn't have one here */ +#ifdef CC_USING_FENTRY + lea 4*4(%esp), %edx + movl $0, %ecx +#else + lea 0x4(%ebp), %edx + movl (%ebp), %ecx +#endif + subl $MCOUNT_INSN_SIZE, %eax + call prepare_ftrace_return + popl %edx + popl %ecx + popl %eax + ret +END(ftrace_graph_caller) + +.globl return_to_handler +return_to_handler: + pushl %eax + pushl %edx +#ifdef CC_USING_FENTRY + movl $0, %eax +#else + movl %ebp, %eax +#endif + call ftrace_return_to_handler + movl %eax, %ecx + popl %edx + popl %eax + JMP_NOSPEC %ecx +#endif |