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/*
* 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>
#ifdef CONFIG_FUNCTION_TRACER
#ifdef CONFIG_DYNAMIC_FTRACE
ENTRY(mcount)
ret
END(mcount)
ENTRY(ftrace_caller)
pushl %eax
pushl %ecx
pushl %edx
pushl $0 /* Pass NULL as regs pointer */
movl 4*4(%esp), %eax
movl 0x4(%ebp), %edx
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
.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)
pushf /* push flags before compare (in cs location) */
/*
* 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
* ip location, and move flags into the return ip location.
*/
pushl 4(%esp) /* save return ip into ip slot */
pushl $0 /* Load 0 into orig_ax */
pushl %gs
pushl %fs
pushl %es
pushl %ds
pushl %eax
pushl %ebp
pushl %edi
pushl %esi
pushl %edx
pushl %ecx
pushl %ebx
movl 13*4(%esp), %eax /* Get the saved flags */
movl %eax, 14*4(%esp) /* Move saved flags into regs->flags location */
/* clobbering return ip */
movl $__KERNEL_CS, 13*4(%esp)
movl 12*4(%esp), %eax /* Load ip (1st parameter) */
subl $MCOUNT_INSN_SIZE, %eax /* Adjust ip */
movl 0x4(%ebp), %edx /* Load parent ip (2nd parameter) */
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 */
movl 14*4(%esp), %eax /* Move flags back into cs */
movl %eax, 13*4(%esp) /* Needed to keep addl from modifying flags */
movl 12*4(%esp), %eax /* Get return ip from regs->ip */
movl %eax, 14*4(%esp) /* Put return ip back for ret */
popl %ebx
popl %ecx
popl %edx
popl %esi
popl %edi
popl %ebp
popl %eax
popl %ds
popl %es
popl %fs
popl %gs
addl $8, %esp /* Skip orig_ax and ip */
popf /* Pop flags at end (no addl to corrupt flags) */
jmp .Lftrace_ret
popf
jmp ftrace_stub
#else /* ! CONFIG_DYNAMIC_FTRACE */
ENTRY(mcount)
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
call *ftrace_trace_function
popl %edx
popl %ecx
popl %eax
jmp ftrace_stub
END(mcount)
#endif /* CONFIG_DYNAMIC_FTRACE */
EXPORT_SYMBOL(mcount)
#endif /* CONFIG_FUNCTION_TRACER */
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
ENTRY(ftrace_graph_caller)
pushl %eax
pushl %ecx
pushl %edx
movl 0xc(%esp), %eax
lea 0x4(%ebp), %edx
movl (%ebp), %ecx
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
movl %ebp, %eax
call ftrace_return_to_handler
movl %eax, %ecx
popl %edx
popl %eax
jmp *%ecx
#endif
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