diff --git a/arch/arm/include/asm/ftrace.h b/arch/arm/include/asm/ftrace.h
index 103f7ee9731357fa7a8e19bb83416a1465c53cb4..4a56a2ee067cb5e4fe7a071417c8731717fdff1a 100644
--- a/arch/arm/include/asm/ftrace.h
+++ b/arch/arm/include/asm/ftrace.h
@@ -2,12 +2,29 @@
#define _ASM_ARM_FTRACE
#ifdef CONFIG_FUNCTION_TRACER
-#define MCOUNT_ADDR ((long)(mcount))
+#define MCOUNT_ADDR ((unsigned long)(__gnu_mcount_nc))
#define MCOUNT_INSN_SIZE 4 /* sizeof mcount call */
#ifndef __ASSEMBLY__
extern void mcount(void);
extern void __gnu_mcount_nc(void);
+
+#ifdef CONFIG_DYNAMIC_FTRACE
+struct dyn_arch_ftrace {
+#ifdef CONFIG_OLD_MCOUNT
+ bool old_mcount;
+#endif
+};
+
+static inline unsigned long ftrace_call_adjust(unsigned long addr)
+{
+ return addr;
+}
+
+extern void ftrace_caller_old(void);
+extern void ftrace_call_old(void);
+#endif
+
#endif
#endif
diff --git a/arch/arm/kernel/entry-common.S b/arch/arm/kernel/entry-common.S
index f5e75de0203ece98c992aae351e2ab068b7bde99..e02790f28879c9969c0a1d4687a374c13eb98994 100644
--- a/arch/arm/kernel/entry-common.S
+++ b/arch/arm/kernel/entry-common.S
@@ -127,6 +127,10 @@ ENDPROC(ret_from_fork)
* clobber the ip register. This is OK because the ARM calling convention
* allows it to be clobbered in subroutines and doesn't use it to hold
* parameters.)
+ *
+ * When using dynamic ftrace, we patch out the mcount call by a "mov r0, r0"
+ * for the mcount case, and a "pop {lr}" for the __gnu_mcount_nc case (see
+ * arch/arm/kernel/ftrace.c).
*/
#ifndef CONFIG_OLD_MCOUNT
@@ -136,30 +140,45 @@ ENDPROC(ret_from_fork)
#endif
#ifdef CONFIG_DYNAMIC_FTRACE
-ENTRY(mcount)
+ENTRY(__gnu_mcount_nc)
+ mov ip, lr
+ ldmia sp!, {lr}
+ mov pc, ip
+ENDPROC(__gnu_mcount_nc)
+
+ENTRY(ftrace_caller)
stmdb sp!, {r0-r3, lr}
mov r0, lr
sub r0, r0, #MCOUNT_INSN_SIZE
+ ldr r1, [sp, #20]
- .globl mcount_call
-mcount_call:
+ .global ftrace_call
+ftrace_call:
bl ftrace_stub
- ldr lr, [fp, #-4] @ restore lr
- ldmia sp!, {r0-r3, pc}
+ ldmia sp!, {r0-r3, ip, lr}
+ mov pc, ip
+ENDPROC(ftrace_caller)
+
+#ifdef CONFIG_OLD_MCOUNT
+ENTRY(mcount)
+ stmdb sp!, {lr}
+ ldr lr, [fp, #-4]
+ ldmia sp!, {pc}
ENDPROC(mcount)
-ENTRY(ftrace_caller)
+ENTRY(ftrace_caller_old)
stmdb sp!, {r0-r3, lr}
ldr r1, [fp, #-4]
mov r0, lr
sub r0, r0, #MCOUNT_INSN_SIZE
- .globl ftrace_call
-ftrace_call:
+ .globl ftrace_call_old
+ftrace_call_old:
bl ftrace_stub
ldr lr, [fp, #-4] @ restore lr
ldmia sp!, {r0-r3, pc}
-ENDPROC(ftrace_caller)
+ENDPROC(ftrace_caller_old)
+#endif
#else
diff --git a/arch/arm/kernel/ftrace.c b/arch/arm/kernel/ftrace.c
index 0298286ad4ad5971302a6690c5046e66826bccb2..f09014cfbf2c3bd0e0a41f930008f53fd28be75b 100644
--- a/arch/arm/kernel/ftrace.c
+++ b/arch/arm/kernel/ftrace.c
@@ -2,102 +2,161 @@
* Dynamic function tracing support.
*
* Copyright (C) 2008 Abhishek Sagar <sagar.abhishek@gmail.com>
+ * Copyright (C) 2010 Rabin Vincent <rabin@rab.in>
*
* For licencing details, see COPYING.
*
* Defines low-level handling of mcount calls when the kernel
* is compiled with the -pg flag. When using dynamic ftrace, the
- * mcount call-sites get patched lazily with NOP till they are
- * enabled. All code mutation routines here take effect atomically.
+ * mcount call-sites get patched with NOP till they are enabled.
+ * All code mutation routines here are called under stop_machine().
*/
#include <linux/ftrace.h>
+#include <linux/uaccess.h>
#include <asm/cacheflush.h>
#include <asm/ftrace.h>
-#define PC_OFFSET 8
-#define BL_OPCODE 0xeb000000
-#define BL_OFFSET_MASK 0x00ffffff
+#define NOP 0xe8bd4000 /* pop {lr} */
-static unsigned long bl_insn;
-static const unsigned long NOP = 0xe1a00000; /* mov r0, r0 */
+#ifdef CONFIG_OLD_MCOUNT
+#define OLD_MCOUNT_ADDR ((unsigned long) mcount)
+#define OLD_FTRACE_ADDR ((unsigned long) ftrace_caller_old)
-unsigned char *ftrace_nop_replace(void)
+#define OLD_NOP 0xe1a00000 /* mov r0, r0 */
+
+static unsigned long ftrace_nop_replace(struct dyn_ftrace *rec)
+{
+ return rec->arch.old_mcount ? OLD_NOP : NOP;
+}
+
+static unsigned long adjust_address(struct dyn_ftrace *rec, unsigned long addr)
+{
+ if (!rec->arch.old_mcount)
+ return addr;
+
+ if (addr == MCOUNT_ADDR)
+ addr = OLD_MCOUNT_ADDR;
+ else if (addr == FTRACE_ADDR)
+ addr = OLD_FTRACE_ADDR;
+
+ return addr;
+}
+#else
+static unsigned long ftrace_nop_replace(struct dyn_ftrace *rec)
+{
+ return NOP;
+}
+
+static unsigned long adjust_address(struct dyn_ftrace *rec, unsigned long addr)
{
- return (char *)&NOP;
+ return addr;
}
+#endif
/* construct a branch (BL) instruction to addr */
-unsigned char *ftrace_call_replace(unsigned long pc, unsigned long addr)
+static unsigned long ftrace_call_replace(unsigned long pc, unsigned long addr)
{
long offset;
- offset = (long)addr - (long)(pc + PC_OFFSET);
+ offset = (long)addr - (long)(pc + 8);
if (unlikely(offset < -33554432 || offset > 33554428)) {
/* Can't generate branches that far (from ARM ARM). Ftrace
* doesn't generate branches outside of kernel text.
*/
WARN_ON_ONCE(1);
- return NULL;
+ return 0;
}
- offset = (offset >> 2) & BL_OFFSET_MASK;
- bl_insn = BL_OPCODE | offset;
- return (unsigned char *)&bl_insn;
-}
-int ftrace_modify_code(unsigned long pc, unsigned char *old_code,
- unsigned char *new_code)
-{
- unsigned long err = 0, replaced = 0, old, new;
+ offset = (offset >> 2) & 0x00ffffff;
- old = *(unsigned long *)old_code;
- new = *(unsigned long *)new_code;
+ return 0xeb000000 | offset;
+}
- __asm__ __volatile__ (
- "1: ldr %1, [%2] \n"
- " cmp %1, %4 \n"
- "2: streq %3, [%2] \n"
- " cmpne %1, %3 \n"
- " movne %0, #2 \n"
- "3:\n"
+static int ftrace_modify_code(unsigned long pc, unsigned long old,
+ unsigned long new)
+{
+ unsigned long replaced;
- ".pushsection .fixup, \"ax\"\n"
- "4: mov %0, #1 \n"
- " b 3b \n"
- ".popsection\n"
+ if (probe_kernel_read(&replaced, (void *)pc, MCOUNT_INSN_SIZE))
+ return -EFAULT;
- ".pushsection __ex_table, \"a\"\n"
- " .long 1b, 4b \n"
- " .long 2b, 4b \n"
- ".popsection\n"
+ if (replaced != old)
+ return -EINVAL;
- : "=r"(err), "=r"(replaced)
- : "r"(pc), "r"(new), "r"(old), "0"(err), "1"(replaced)
- : "memory");
+ if (probe_kernel_write((void *)pc, &new, MCOUNT_INSN_SIZE))
+ return -EPERM;
- if (!err && (replaced == old))
- flush_icache_range(pc, pc + MCOUNT_INSN_SIZE);
+ flush_icache_range(pc, pc + MCOUNT_INSN_SIZE);
- return err;
+ return 0;
}
int ftrace_update_ftrace_func(ftrace_func_t func)
{
- int ret;
unsigned long pc, old;
- unsigned char *new;
+ unsigned long new;
+ int ret;
pc = (unsigned long)&ftrace_call;
memcpy(&old, &ftrace_call, MCOUNT_INSN_SIZE);
new = ftrace_call_replace(pc, (unsigned long)func);
- ret = ftrace_modify_code(pc, (unsigned char *)&old, new);
+
+ ret = ftrace_modify_code(pc, old, new);
+
+#ifdef CONFIG_OLD_MCOUNT
+ if (!ret) {
+ pc = (unsigned long)&ftrace_call_old;
+ memcpy(&old, &ftrace_call_old, MCOUNT_INSN_SIZE);
+ new = ftrace_call_replace(pc, (unsigned long)func);
+
+ ret = ftrace_modify_code(pc, old, new);
+ }
+#endif
+
+ return ret;
+}
+
+int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
+{
+ unsigned long new, old;
+ unsigned long ip = rec->ip;
+
+ old = ftrace_nop_replace(rec);
+ new = ftrace_call_replace(ip, adjust_address(rec, addr));
+
+ return ftrace_modify_code(rec->ip, old, new);
+}
+
+int ftrace_make_nop(struct module *mod,
+ struct dyn_ftrace *rec, unsigned long addr)
+{
+ unsigned long ip = rec->ip;
+ unsigned long old;
+ unsigned long new;
+ int ret;
+
+ old = ftrace_call_replace(ip, adjust_address(rec, addr));
+ new = ftrace_nop_replace(rec);
+ ret = ftrace_modify_code(ip, old, new);
+
+#ifdef CONFIG_OLD_MCOUNT
+ if (ret == -EINVAL && addr == MCOUNT_ADDR) {
+ rec->arch.old_mcount = true;
+
+ old = ftrace_call_replace(ip, adjust_address(rec, addr));
+ new = ftrace_nop_replace(rec);
+ ret = ftrace_modify_code(ip, old, new);
+ }
+#endif
+
return ret;
}
-/* run from ftrace_init with irqs disabled */
int __init ftrace_dyn_arch_init(void *data)
{
- ftrace_mcount_set(data);
+ *(unsigned long *)data = 0;
+
return 0;
}
diff --git a/scripts/recordmcount.pl b/scripts/recordmcount.pl
index e67f054860877d676fc4359ef2f670b5d7531479..022d4679b1b3bcd9e964b7d66bbf1e8e8e1cfc36 100755
--- a/scripts/recordmcount.pl
+++ b/scripts/recordmcount.pl
@@ -270,6 +270,8 @@ if ($arch eq "x86_64") {
} elsif ($arch eq "arm") {
$alignment = 2;
$section_type = '%progbits';
+ $mcount_regex = "^\\s*([0-9a-fA-F]+):\\s*R_ARM_(CALL|PC24)" .
+ "\\s+(__gnu_mcount_nc|mcount)\$";
} elsif ($arch eq "ia64") {
$mcount_regex = "^\\s*([0-9a-fA-F]+):.*\\s_mcount\$";