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Date: Wed, 15 Aug 2018 17:35:21 +0800
From: Zong Li <zong@...estech.com>
To: <green.hu@...il.com>, <deanbo422@...il.com>, <rostedt@...dmis.org>,
<mingo@...hat.com>, <arnd@...db.de>, <linux-kernel@...r.kernel.org>
CC: <zongbox@...il.com>, <greentime@...estech.com>,
Zong Li <zong@...estech.com>
Subject: [PATCH 4/6] nds32/ftrace: Support dynamic function tracer
This patch contains the implementation of dynamic function tracer.
The mcount call is composed of three instructions, so there are three
nop for enough placeholder.
Signed-off-by: Zong Li <zong@...estech.com>
---
arch/nds32/Kconfig | 1 +
arch/nds32/include/asm/ftrace.h | 26 +++++++
arch/nds32/kernel/ftrace.c | 164 ++++++++++++++++++++++++++++++++++++++++
3 files changed, 191 insertions(+)
diff --git a/arch/nds32/Kconfig b/arch/nds32/Kconfig
index 66d507d..9db36c2 100644
--- a/arch/nds32/Kconfig
+++ b/arch/nds32/Kconfig
@@ -43,6 +43,7 @@ config NDS32
select HAVE_FUNCTION_TRACER
select HAVE_FUNCTION_GRAPH_TRACER
select HAVE_FTRACE_MCOUNT_RECORD
+ select HAVE_DYNAMIC_FTRACE
help
Andes(nds32) Linux support.
diff --git a/arch/nds32/include/asm/ftrace.h b/arch/nds32/include/asm/ftrace.h
index bac7657..2f96cc9 100644
--- a/arch/nds32/include/asm/ftrace.h
+++ b/arch/nds32/include/asm/ftrace.h
@@ -15,6 +15,32 @@
extern void _mcount(unsigned long parent_ip);
+#ifdef CONFIG_DYNAMIC_FTRACE
+
+#define FTRACE_ADDR ((unsigned long)_ftrace_caller)
+
+#ifdef __NDS32_EL__
+#define INSN_NOP 0x09000040
+#define INSN_SIZE(insn) (((insn & 0x00000080) == 0) ? 4 : 2)
+#define IS_SETHI(insn) ((insn & 0x000000fe) == 0x00000046)
+#define ENDIAN_CONVERT(insn) be32_to_cpu(insn)
+#else /* __NDS32_EB__ */
+#define INSN_NOP 0x40000009
+#define INSN_SIZE(insn) (((insn & 0x80000000) == 0) ? 4 : 2)
+#define IS_SETHI(insn) ((insn & 0xfe000000) == 0x46000000)
+#define ENDIAN_CONVERT(insn) (insn)
+#endif
+
+extern void _ftrace_caller(unsigned long parent_ip);
+static inline unsigned long ftrace_call_adjust(unsigned long addr)
+{
+ return addr;
+}
+struct dyn_arch_ftrace {
+};
+
+#endif /* CONFIG_DYNAMIC_FTRACE */
+
#endif /* CONFIG_FUNCTION_TRACER */
#endif /* __ASM_NDS32_FTRACE_H */
diff --git a/arch/nds32/kernel/ftrace.c b/arch/nds32/kernel/ftrace.c
index 707fce7..3ca676b 100644
--- a/arch/nds32/kernel/ftrace.c
+++ b/arch/nds32/kernel/ftrace.c
@@ -4,6 +4,7 @@
#include <linux/uaccess.h>
#include <asm/cacheflush.h>
+#ifndef CONFIG_DYNAMIC_FTRACE
extern void (*ftrace_trace_function)(unsigned long, unsigned long,
struct ftrace_ops*, struct pt_regs*);
extern int ftrace_graph_entry_stub(struct ftrace_graph_ent *trace);
@@ -35,6 +36,168 @@ noinline void _mcount(unsigned long parent_ip)
}
EXPORT_SYMBOL(_mcount);
+#else /* CONFIG_DYNAMIC_FTRACE */
+
+noinline void __naked ftrace_stub(unsigned long ip, unsigned long parent_ip,
+ struct ftrace_ops *op, struct pt_regs *regs)
+{
+ __asm__ (""); /* avoid to optimize as pure function */
+}
+
+noinline void __naked _mcount(unsigned long parent_ip)
+{
+ __asm__ (""); /* avoid to optimize as pure function */
+}
+EXPORT_SYMBOL(_mcount);
+
+#define XSTR(s) STR(s)
+#define STR(s) #s
+void _ftrace_caller(unsigned long parent_ip)
+{
+ /* save all state needed by the compiler prologue */
+
+ /*
+ * prepare arguments for real tracing function
+ * first arg : __builtin_return_address(0) - MCOUNT_INSN_SIZE
+ * second arg : parent_ip
+ */
+ __asm__ __volatile__ (
+ "move $r1, %0 \n\t"
+ "addi $r0, %1, #-" XSTR(MCOUNT_INSN_SIZE) "\n\t"
+ :
+ : "r" (parent_ip), "r" (__builtin_return_address(0)));
+
+ /* a placeholder for the call to a real tracing function */
+ __asm__ __volatile__ (
+ "ftrace_call: \n\t"
+ "nop \n\t"
+ "nop \n\t"
+ "nop \n\t");
+
+ /* restore all state needed by the compiler epilogue */
+}
+
+int __init ftrace_dyn_arch_init(void)
+{
+ return 0;
+}
+
+int ftrace_arch_code_modify_prepare(void)
+{
+ set_all_modules_text_rw();
+ return 0;
+}
+
+int ftrace_arch_code_modify_post_process(void)
+{
+ set_all_modules_text_ro();
+ return 0;
+}
+
+static unsigned long gen_sethi_insn(unsigned long addr)
+{
+ unsigned long opcode = 0x46000000;
+ unsigned long imm = addr >> 12;
+ unsigned long rt_num = 0xf << 20;
+
+ return ENDIAN_CONVERT(opcode | rt_num | imm);
+}
+
+static unsigned long gen_ori_insn(unsigned long addr)
+{
+ unsigned long opcode = 0x58000000;
+ unsigned long imm = addr & 0x0000fff;
+ unsigned long rt_num = 0xf << 20;
+ unsigned long ra_num = 0xf << 15;
+
+ return ENDIAN_CONVERT(opcode | rt_num | ra_num | imm);
+}
+
+static unsigned long gen_jral_insn(unsigned long addr)
+{
+ unsigned long opcode = 0x4a000001;
+ unsigned long rt_num = 0x1e << 20;
+ unsigned long rb_num = 0xf << 10;
+
+ return ENDIAN_CONVERT(opcode | rt_num | rb_num);
+}
+
+static void ftrace_gen_call_insn(unsigned long *call_insns,
+ unsigned long addr)
+{
+ call_insns[0] = gen_sethi_insn(addr); /* sethi $r15, imm20u */
+ call_insns[1] = gen_ori_insn(addr); /* ori $r15, $r15, imm15u */
+ call_insns[2] = gen_jral_insn(addr); /* jral $lp, $r15 */
+}
+
+static int __ftrace_modify_code(unsigned long pc, unsigned long *old_insn,
+ unsigned long *new_insn, bool validate)
+{
+ unsigned long orig_insn[3];
+
+ if (validate) {
+ if (probe_kernel_read(orig_insn, (void *)pc, MCOUNT_INSN_SIZE))
+ return -EFAULT;
+ if (memcmp(orig_insn, old_insn, MCOUNT_INSN_SIZE))
+ return -EINVAL;
+ }
+
+ if (probe_kernel_write((void *)pc, new_insn, MCOUNT_INSN_SIZE))
+ return -EPERM;
+
+ return 0;
+}
+
+static int ftrace_modify_code(unsigned long pc, unsigned long *old_insn,
+ unsigned long *new_insn, bool validate)
+{
+ int ret;
+
+ ret = __ftrace_modify_code(pc, old_insn, new_insn, validate);
+ if (ret)
+ return ret;
+
+ flush_icache_range(pc, pc + MCOUNT_INSN_SIZE);
+
+ return ret;
+}
+
+int ftrace_update_ftrace_func(ftrace_func_t func)
+{
+ unsigned long pc = (unsigned long)&ftrace_call;
+ unsigned long old_insn[3] = {INSN_NOP, INSN_NOP, INSN_NOP};
+ unsigned long new_insn[3] = {INSN_NOP, INSN_NOP, INSN_NOP};
+
+ if (func != ftrace_stub)
+ ftrace_gen_call_insn(new_insn, (unsigned long)func);
+
+ return ftrace_modify_code(pc, old_insn, new_insn, false);
+}
+
+int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
+{
+ unsigned long pc = rec->ip;
+ unsigned long nop_insn[3] = {INSN_NOP, INSN_NOP, INSN_NOP};
+ unsigned long call_insn[3] = {INSN_NOP, INSN_NOP, INSN_NOP};
+
+ ftrace_gen_call_insn(call_insn, addr);
+
+ return ftrace_modify_code(pc, nop_insn, call_insn, true);
+}
+
+int ftrace_make_nop(struct module *mod, struct dyn_ftrace *rec,
+ unsigned long addr)
+{
+ unsigned long pc = rec->ip;
+ unsigned long nop_insn[3] = {INSN_NOP, INSN_NOP, INSN_NOP};
+ unsigned long call_insn[3] = {INSN_NOP, INSN_NOP, INSN_NOP};
+
+ ftrace_gen_call_insn(call_insn, addr);
+
+ return ftrace_modify_code(pc, call_insn, nop_insn, true);
+}
+#endif /* CONFIG_DYNAMIC_FTRACE */
+
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr,
unsigned long frame_pointer)
@@ -94,4 +257,5 @@ void __naked return_to_handler(void)
/* restore state nedded by the ABI */
"lmw.bim $r0,[$sp],$r1,#0x0 \n\t");
}
+
#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
--
2.7.4
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