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ftrace/x86: Add macro MCOUNT_REG_SIZE for amount of stack used to save mcount regs

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The macro save_mcount_regs saves regs onto the stack. But to uncouple the
amount of stack used in that macro from the users of the macro, we need
to have a define that tells all the users how much stack is used by that
macro. This way we can change the amount of stack the macro uses without
breaking its users.

Also remove some dead code that was left over from commit fdc841b58c
"ftrace: x86: Remove check of obsolete variable function_trace_stop".

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>
This commit is contained in:
Steven Rostedt (Red Hat) 2014-11-24 14:26:38 -05:00 committed by Steven Rostedt
parent 527aa75b33
commit 85f6f0290c
1 changed files with 12 additions and 12 deletions
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24
arch/x86/kernel/mcount_64.S
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@ -21,6 +21,9 @@
# define function_hook mcount
#endif
/* Size of stack used to save mcount regs in save_mcount_regs */
#define MCOUNT_REG_SIZE (SS+8)
/*
* gcc -pg option adds a call to 'mcount' in most functions.
* When -mfentry is used, the call is to 'fentry' and not 'mcount'
@ -42,7 +45,7 @@
/*
* We add enough stack to save all regs.
*/
subq $(SS+8), %rsp
subq $MCOUNT_REG_SIZE, %rsp
movq %rax, RAX(%rsp)
movq %rcx, RCX(%rsp)
movq %rdx, RDX(%rsp)
@ -51,7 +54,7 @@
movq %r8, R8(%rsp)
movq %r9, R9(%rsp)
/* Move RIP to its proper location */
movq SS+8+\added(%rsp), %rdi
movq MCOUNT_REG_SIZE+\added(%rsp), %rdi
movq %rdi, RIP(%rsp)
.endm
@ -63,7 +66,7 @@
movq RDX(%rsp), %rdx
movq RCX(%rsp), %rcx
movq RAX(%rsp), %rax
addq $(SS+8), %rsp
addq $MCOUNT_REG_SIZE, %rsp
.endm
/* skip is set if stack has been adjusted */
@ -79,7 +82,7 @@ GLOBAL(\trace_label)
subq $MCOUNT_INSN_SIZE, %rdi
/* Load the parent_ip into the second parameter */
#ifdef CC_USING_FENTRY
movq SS+16+\added(%rsp), %rsi
movq MCOUNT_REG_SIZE+8+\added(%rsp), %rsi
#else
movq 8+\added(%rbp), %rsi
#endif
@ -172,7 +175,7 @@ ENTRY(ftrace_regs_caller)
movq %rbp, RBP(%rsp)
movq %rbx, RBX(%rsp)
/* Copy saved flags */
movq SS+8(%rsp), %rcx
movq MCOUNT_REG_SIZE(%rsp), %rcx
movq %rcx, EFLAGS(%rsp)
/* Kernel segments */
movq $__KERNEL_DS, %rcx
@ -180,7 +183,7 @@ ENTRY(ftrace_regs_caller)
movq $__KERNEL_CS, %rcx
movq %rcx, CS(%rsp)
/* Stack - skipping return address and flags */
leaq SS+8*3(%rsp), %rcx
leaq MCOUNT_REG_SIZE+8*2(%rsp), %rcx
movq %rcx, RSP(%rsp)
/* regs go into 4th parameter */
@ -195,11 +198,11 @@ GLOBAL(ftrace_regs_call)
/* Copy flags back to SS, to restore them */
movq EFLAGS(%rsp), %rax
movq %rax, SS+8(%rsp)
movq %rax, MCOUNT_REG_SIZE(%rsp)
/* Handlers can change the RIP */
movq RIP(%rsp), %rax
movq %rax, SS+8*2(%rsp)
movq %rax, MCOUNT_REG_SIZE+8(%rsp)
/* restore the rest of pt_regs */
movq R15(%rsp), %r15
@ -225,9 +228,6 @@ GLOBAL(ftrace_regs_caller_end)
jmp ftrace_return
popfq
jmp ftrace_stub
END(ftrace_regs_caller)
@ -266,7 +266,7 @@ ENTRY(ftrace_graph_caller)
save_mcount_regs
#ifdef CC_USING_FENTRY
leaq SS+16(%rsp), %rdi
leaq MCOUNT_REG_SIZE+8(%rsp), %rdi
movq $0, %rdx /* No framepointers needed */
#else
leaq 8(%rbp), %rdi