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-rw-r--r--arch/x86/kernel/ftrace_32.S193
1 files changed, 193 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..a0ed0e4a2
--- /dev/null
+++ b/arch/x86/kernel/ftrace_32.S
@@ -0,0 +1,193 @@
+/* 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>
+#include <asm/asm-offsets.h>
+
+#ifdef CONFIG_FRAME_POINTER
+# define MCOUNT_FRAME 1 /* using frame = true */
+#else
+# define MCOUNT_FRAME 0 /* using frame = false */
+#endif
+
+SYM_FUNC_START(__fentry__)
+ RET
+SYM_FUNC_END(__fentry__)
+EXPORT_SYMBOL(__fentry__)
+
+SYM_CODE_START(ftrace_caller)
+
+#ifdef CONFIG_FRAME_POINTER
+ /*
+ * 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 */
+
+ /* 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 CONFIG_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 CONFIG_FRAME_POINTER
+ popl %ebp
+ addl $4,%esp /* skip function ip */
+ popl %ebp /* this is the orig bp */
+ addl $4, %esp /* skip parent ip */
+#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 */
+SYM_INNER_LABEL_ALIGN(ftrace_stub, SYM_L_WEAK)
+ RET
+SYM_CODE_END(ftrace_caller)
+
+SYM_CODE_START(ftrace_regs_caller)
+ /*
+ * We're here from an mcount/fentry CALL, and the stack frame looks like:
+ *
+ * <previous context>
+ * RET-IP
+ *
+ * The purpose of this function is to call out in an emulated INT3
+ * environment with a stack frame like:
+ *
+ * <previous context>
+ * gap / RET-IP
+ * gap
+ * gap
+ * gap
+ * pt_regs
+ *
+ * We do _NOT_ restore: ss, flags, cs, gs, fs, es, ds
+ */
+ subl $3*4, %esp # RET-IP + 3 gaps
+ pushl %ss # ss
+ pushl %esp # points at ss
+ addl $5*4, (%esp) # make it point at <previous context>
+ pushfl # flags
+ pushl $__KERNEL_CS # cs
+ pushl 7*4(%esp) # ip <- RET-IP
+ pushl $0 # orig_eax
+
+ pushl %gs
+ pushl %fs
+ pushl %es
+ pushl %ds
+
+ pushl %eax
+ pushl %ebp
+ pushl %edi
+ pushl %esi
+ pushl %edx
+ pushl %ecx
+ pushl %ebx
+
+ ENCODE_FRAME_POINTER
+
+ movl PT_EIP(%esp), %eax # 1st argument: IP
+ subl $MCOUNT_INSN_SIZE, %eax
+ movl 21*4(%esp), %edx # 2nd argument: parent ip
+ movl function_trace_op, %ecx # 3rd argument: ftrace_pos
+ pushl %esp # 4th argument: pt_regs
+
+SYM_INNER_LABEL(ftrace_regs_call, SYM_L_GLOBAL)
+ call ftrace_stub
+
+ addl $4, %esp # skip 4th argument
+
+ /* place IP below the new SP */
+ movl PT_OLDESP(%esp), %eax
+ movl PT_EIP(%esp), %ecx
+ movl %ecx, -4(%eax)
+
+ /* place EAX below that */
+ movl PT_EAX(%esp), %ecx
+ movl %ecx, -8(%eax)
+
+ popl %ebx
+ popl %ecx
+ popl %edx
+ popl %esi
+ popl %edi
+ popl %ebp
+
+ lea -8(%eax), %esp
+ popl %eax
+
+ jmp .Lftrace_ret
+SYM_CODE_END(ftrace_regs_caller)
+
+#ifdef CONFIG_FUNCTION_GRAPH_TRACER
+SYM_CODE_START(ftrace_graph_caller)
+ pushl %eax
+ pushl %ecx
+ pushl %edx
+ movl 3*4(%esp), %eax
+ /* Even with frame pointers, fentry doesn't have one here */
+ lea 4*4(%esp), %edx
+ movl $0, %ecx
+ subl $MCOUNT_INSN_SIZE, %eax
+ call prepare_ftrace_return
+ popl %edx
+ popl %ecx
+ popl %eax
+ RET
+SYM_CODE_END(ftrace_graph_caller)
+
+.globl return_to_handler
+return_to_handler:
+ pushl %eax
+ pushl %edx
+ movl $0, %eax
+ call ftrace_return_to_handler
+ movl %eax, %ecx
+ popl %edx
+ popl %eax
+ JMP_NOSPEC ecx
+#endif