lkml.org 
[lkml]   [2018]   [Aug]   [15]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH 4/6] nds32/ftrace: Support dynamic function tracer
Date
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@andestech.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
\
 
 \ /
  Last update: 2018-08-15 11:37    [W:2.097 / U:0.024 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site