linux/arch/x86/kernel/mcount_64.S
Steven Rostedt (Red Hat) 6a06bdbf7f ftrace/fgraph/x86: Have prepare_ftrace_return() take ip as first parameter
The function graph helper function prepare_ftrace_return() which does the work
to hijack the parent pointer has that parent pointer as its first parameter.
Instead, if we make it the second parameter and have ip as the first parameter
(self_addr), then it can use the %rdi from save_mcount_regs that loads it
already.

Link: http://lkml.kernel.org/r/alpine.DEB.2.11.1411262304010.3961@nanos

Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2014-12-01 14:08:58 -05:00

327 lines
7.4 KiB
ArmAsm

/*
* linux/arch/x86_64/mcount_64.S
*
* Copyright (C) 2014 Steven Rostedt, Red Hat Inc
*/
#include <linux/linkage.h>
#include <asm/ptrace.h>
#include <asm/ftrace.h>
.code64
.section .entry.text, "ax"
#ifdef CONFIG_FUNCTION_TRACER
#ifdef CC_USING_FENTRY
# define function_hook __fentry__
#else
# define function_hook mcount
#endif
/* All cases save the original rbp (8 bytes) */
#ifdef CONFIG_FRAME_POINTER
# ifdef CC_USING_FENTRY
/* Save parent and function stack frames (rip and rbp) */
# define MCOUNT_FRAME_SIZE (8+16*2)
# else
/* Save just function stack frame (rip and rbp) */
# define MCOUNT_FRAME_SIZE (8+16)
# endif
#else
/* No need to save a stack frame */
# define MCOUNT_FRAME_SIZE 8
#endif /* CONFIG_FRAME_POINTER */
/* Size of stack used to save mcount regs in save_mcount_regs */
#define MCOUNT_REG_SIZE (SS+8 + MCOUNT_FRAME_SIZE)
/*
* gcc -pg option adds a call to 'mcount' in most functions.
* When -mfentry is used, the call is to 'fentry' and not 'mcount'
* and is done before the function's stack frame is set up.
* They both require a set of regs to be saved before calling
* any C code and restored before returning back to the function.
*
* On boot up, all these calls are converted into nops. When tracing
* is enabled, the call can jump to either ftrace_caller or
* ftrace_regs_caller. Callbacks (tracing functions) that require
* ftrace_regs_caller (like kprobes) need to have pt_regs passed to
* it. For this reason, the size of the pt_regs structure will be
* allocated on the stack and the required mcount registers will
* be saved in the locations that pt_regs has them in.
*/
/*
* @added: the amount of stack added before calling this
*
* After this is called, the following registers contain:
*
* %rdi - holds the address that called the trampoline
* %rsi - holds the parent function (traced function's return address)
* %rdx - holds the original %rbp
*/
.macro save_mcount_regs added=0
/* Always save the original rbp */
pushq %rbp
#ifdef CONFIG_FRAME_POINTER
/*
* Stack traces will stop at the ftrace trampoline if the frame pointer
* is not set up properly. If fentry is used, we need to save a frame
* pointer for the parent as well as the function traced, because the
* fentry is called before the stack frame is set up, where as mcount
* is called afterward.
*/
#ifdef CC_USING_FENTRY
/* Save the parent pointer (skip orig rbp and our return address) */
pushq \added+8*2(%rsp)
pushq %rbp
movq %rsp, %rbp
/* Save the return address (now skip orig rbp, rbp and parent) */
pushq \added+8*3(%rsp)
#else
/* Can't assume that rip is before this (unless added was zero) */
pushq \added+8(%rsp)
#endif
pushq %rbp
movq %rsp, %rbp
#endif /* CONFIG_FRAME_POINTER */
/*
* We add enough stack to save all regs.
*/
subq $(MCOUNT_REG_SIZE - MCOUNT_FRAME_SIZE), %rsp
movq %rax, RAX(%rsp)
movq %rcx, RCX(%rsp)
movq %rdx, RDX(%rsp)
movq %rsi, RSI(%rsp)
movq %rdi, RDI(%rsp)
movq %r8, R8(%rsp)
movq %r9, R9(%rsp)
/*
* Save the original RBP. Even though the mcount ABI does not
* require this, it helps out callers.
*/
movq MCOUNT_REG_SIZE-8(%rsp), %rdx
movq %rdx, RBP(%rsp)
/* Copy the parent address into %rsi (second parameter) */
#ifdef CC_USING_FENTRY
movq MCOUNT_REG_SIZE+8+\added(%rsp), %rsi
#else
/* %rdx contains original %rbp */
movq 8(%rdx), %rsi
#endif
/* Move RIP to its proper location */
movq MCOUNT_REG_SIZE+\added(%rsp), %rdi
movq %rdi, RIP(%rsp)
/*
* Now %rdi (the first parameter) has the return address of
* where ftrace_call returns. But the callbacks expect the
* address of the call itself.
*/
subq $MCOUNT_INSN_SIZE, %rdi
.endm
.macro restore_mcount_regs
movq R9(%rsp), %r9
movq R8(%rsp), %r8
movq RDI(%rsp), %rdi
movq RSI(%rsp), %rsi
movq RDX(%rsp), %rdx
movq RCX(%rsp), %rcx
movq RAX(%rsp), %rax
/* ftrace_regs_caller can modify %rbp */
movq RBP(%rsp), %rbp
addq $MCOUNT_REG_SIZE, %rsp
.endm
#ifdef CONFIG_DYNAMIC_FTRACE
ENTRY(function_hook)
retq
END(function_hook)
ENTRY(ftrace_caller)
/* save_mcount_regs fills in first two parameters */
save_mcount_regs
GLOBAL(ftrace_caller_op_ptr)
/* Load the ftrace_ops into the 3rd parameter */
movq function_trace_op(%rip), %rdx
/* regs go into 4th parameter (but make it NULL) */
movq $0, %rcx
GLOBAL(ftrace_call)
call ftrace_stub
restore_mcount_regs
/*
* The copied trampoline must call ftrace_return as it
* still may need to call the function graph tracer.
*/
GLOBAL(ftrace_caller_end)
GLOBAL(ftrace_return)
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
GLOBAL(ftrace_graph_call)
jmp ftrace_stub
#endif
GLOBAL(ftrace_stub)
retq
END(ftrace_caller)
ENTRY(ftrace_regs_caller)
/* Save the current flags before any operations that can change them */
pushfq
/* added 8 bytes to save flags */
save_mcount_regs 8
/* save_mcount_regs fills in first two parameters */
GLOBAL(ftrace_regs_caller_op_ptr)
/* Load the ftrace_ops into the 3rd parameter */
movq function_trace_op(%rip), %rdx
/* Save the rest of pt_regs */
movq %r15, R15(%rsp)
movq %r14, R14(%rsp)
movq %r13, R13(%rsp)
movq %r12, R12(%rsp)
movq %r11, R11(%rsp)
movq %r10, R10(%rsp)
movq %rbx, RBX(%rsp)
/* Copy saved flags */
movq MCOUNT_REG_SIZE(%rsp), %rcx
movq %rcx, EFLAGS(%rsp)
/* Kernel segments */
movq $__KERNEL_DS, %rcx
movq %rcx, SS(%rsp)
movq $__KERNEL_CS, %rcx
movq %rcx, CS(%rsp)
/* Stack - skipping return address and flags */
leaq MCOUNT_REG_SIZE+8*2(%rsp), %rcx
movq %rcx, RSP(%rsp)
/* regs go into 4th parameter */
leaq (%rsp), %rcx
GLOBAL(ftrace_regs_call)
call ftrace_stub
/* Copy flags back to SS, to restore them */
movq EFLAGS(%rsp), %rax
movq %rax, MCOUNT_REG_SIZE(%rsp)
/* Handlers can change the RIP */
movq RIP(%rsp), %rax
movq %rax, MCOUNT_REG_SIZE+8(%rsp)
/* restore the rest of pt_regs */
movq R15(%rsp), %r15
movq R14(%rsp), %r14
movq R13(%rsp), %r13
movq R12(%rsp), %r12
movq R10(%rsp), %r10
movq RBX(%rsp), %rbx
restore_mcount_regs
/* Restore flags */
popfq
/*
* As this jmp to ftrace_return can be a short jump
* it must not be copied into the trampoline.
* The trampoline will add the code to jump
* to the return.
*/
GLOBAL(ftrace_regs_caller_end)
jmp ftrace_return
END(ftrace_regs_caller)
#else /* ! CONFIG_DYNAMIC_FTRACE */
ENTRY(function_hook)
cmpq $ftrace_stub, ftrace_trace_function
jnz trace
fgraph_trace:
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
cmpq $ftrace_stub, ftrace_graph_return
jnz ftrace_graph_caller
cmpq $ftrace_graph_entry_stub, ftrace_graph_entry
jnz ftrace_graph_caller
#endif
GLOBAL(ftrace_stub)
retq
trace:
/* save_mcount_regs fills in first two parameters */
save_mcount_regs
call *ftrace_trace_function
restore_mcount_regs
jmp fgraph_trace
END(function_hook)
#endif /* CONFIG_DYNAMIC_FTRACE */
#endif /* CONFIG_FUNCTION_TRACER */
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
ENTRY(ftrace_graph_caller)
/* Saves rbp into %rdx and fills first parameter */
save_mcount_regs
#ifdef CC_USING_FENTRY
leaq MCOUNT_REG_SIZE+8(%rsp), %rsi
movq $0, %rdx /* No framepointers needed */
#else
/* Save address of the return address of traced function */
leaq 8(%rdx), %rsi
/* ftrace does sanity checks against frame pointers */
movq (%rdx), %rdx
#endif
call prepare_ftrace_return
restore_mcount_regs
retq
END(ftrace_graph_caller)
GLOBAL(return_to_handler)
subq $24, %rsp
/* Save the return values */
movq %rax, (%rsp)
movq %rdx, 8(%rsp)
movq %rbp, %rdi
call ftrace_return_to_handler
movq %rax, %rdi
movq 8(%rsp), %rdx
movq (%rsp), %rax
addq $24, %rsp
jmp *%rdi
#endif