ftrace: add basic support for gcc profiler instrumentation

[mirror_ubuntu-zesty-kernel.git] / arch / x86 / kernel / entry_64.S

diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S
index 556a8df522a7adcf9583164be4cad60e29b00a97..f046e0c6488391416f28e6a747893c85d76d5e10 100644 (file)
--- a/arch/x86/kernel/entry_64.S
+++ b/arch/x86/kernel/entry_64.S
@@ -54,6 +54,43 @@
 
        .code64
 
+#ifdef CONFIG_FTRACE
+ENTRY(mcount)
+       cmpq $ftrace_stub, ftrace_trace_function
+       jnz trace
+.globl ftrace_stub
+ftrace_stub:
+       retq
+
+trace:
+       /* taken from glibc */
+       subq $0x38, %rsp
+       movq %rax, (%rsp)
+       movq %rcx, 8(%rsp)
+       movq %rdx, 16(%rsp)
+       movq %rsi, 24(%rsp)
+       movq %rdi, 32(%rsp)
+       movq %r8, 40(%rsp)
+       movq %r9, 48(%rsp)
+
+       movq 0x38(%rsp), %rdi
+       movq 8(%rbp), %rsi
+
+       call   *ftrace_trace_function
+
+       movq 48(%rsp), %r9
+       movq 40(%rsp), %r8
+       movq 32(%rsp), %rdi
+       movq 24(%rsp), %rsi
+       movq 16(%rsp), %rdx
+       movq 8(%rsp), %rcx
+       movq (%rsp), %rax
+       addq $0x38, %rsp
+
+       jmp ftrace_stub
+END(mcount)
+#endif
+
 #ifndef CONFIG_PREEMPT
 #define retint_kernel retint_restore_args
 #endif