* 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
+#ifdef CONFIG_THUMB2_KERNEL
+#define NOP 0xeb04f85d /* pop.w {lr} */
+#else
+#define NOP 0xe8bd4000 /* pop {lr} */
+#endif
-static unsigned long bl_insn;
-static const unsigned long NOP = 0xe1a00000; /* mov r0, r0 */
+#ifdef CONFIG_DYNAMIC_FTRACE
+#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
+
+#ifdef CONFIG_THUMB2_KERNEL
+static unsigned long ftrace_gen_branch(unsigned long pc, unsigned long addr,
+ bool link)
+{
+ unsigned long s, j1, j2, i1, i2, imm10, imm11;
+ unsigned long first, second;
+ long offset;
+
+ offset = (long)addr - (long)(pc + 4);
+ if (offset < -16777216 || offset > 16777214) {
+ WARN_ON_ONCE(1);
+ return 0;
+ }
+
+ s = (offset >> 24) & 0x1;
+ i1 = (offset >> 23) & 0x1;
+ i2 = (offset >> 22) & 0x1;
+ imm10 = (offset >> 12) & 0x3ff;
+ imm11 = (offset >> 1) & 0x7ff;
+
+ j1 = (!i1) ^ s;
+ j2 = (!i2) ^ s;
+
+ first = 0xf000 | (s << 10) | imm10;
+ second = 0x9000 | (j1 << 13) | (j2 << 11) | imm11;
+ if (link)
+ second |= 1 << 14;
-/* construct a branch (BL) instruction to addr */
-unsigned char *ftrace_call_replace(unsigned long pc, unsigned long addr)
+ return (second << 16) | first;
+}
+#else
+static unsigned long ftrace_gen_branch(unsigned long pc, unsigned long addr,
+ bool link)
{
+ unsigned long opcode = 0xea000000;
long offset;
- offset = (long)addr - (long)(pc + PC_OFFSET);
+ if (link)
+ opcode |= 1 << 24;
+
+ 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;
+
+ offset = (offset >> 2) & 0x00ffffff;
+
+ return opcode | offset;
}
+#endif
-int ftrace_modify_code(unsigned long pc, unsigned char *old_code,
- unsigned char *new_code)
+static unsigned long ftrace_call_replace(unsigned long pc, unsigned long addr)
{
- unsigned long err = 0, replaced = 0, old, new;
-
- old = *(unsigned long *)old_code;
- new = *(unsigned long *)new_code;
+ return ftrace_gen_branch(pc, addr, true);
+}
- __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;
}
+#endif /* CONFIG_DYNAMIC_FTRACE */
+
+#ifdef CONFIG_FUNCTION_GRAPH_TRACER
+void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr,
+ unsigned long frame_pointer)
+{
+ unsigned long return_hooker = (unsigned long) &return_to_handler;
+ struct ftrace_graph_ent trace;
+ unsigned long old;
+ int err;
+
+ if (unlikely(atomic_read(¤t->tracing_graph_pause)))
+ return;
+
+ old = *parent;
+ *parent = return_hooker;
+
+ err = ftrace_push_return_trace(old, self_addr, &trace.depth,
+ frame_pointer);
+ if (err == -EBUSY) {
+ *parent = old;
+ return;
+ }
+
+ trace.func = self_addr;
+
+ /* Only trace if the calling function expects to */
+ if (!ftrace_graph_entry(&trace)) {
+ current->curr_ret_stack--;
+ *parent = old;
+ }
+}
+
+#ifdef CONFIG_DYNAMIC_FTRACE
+extern unsigned long ftrace_graph_call;
+extern unsigned long ftrace_graph_call_old;
+extern void ftrace_graph_caller_old(void);
+
+static int __ftrace_modify_caller(unsigned long *callsite,
+ void (*func) (void), bool enable)
+{
+ unsigned long caller_fn = (unsigned long) func;
+ unsigned long pc = (unsigned long) callsite;
+ unsigned long branch = ftrace_gen_branch(pc, caller_fn, false);
+ unsigned long nop = 0xe1a00000; /* mov r0, r0 */
+ unsigned long old = enable ? nop : branch;
+ unsigned long new = enable ? branch : nop;
+
+ return ftrace_modify_code(pc, old, new);
+}
+
+static int ftrace_modify_graph_caller(bool enable)
+{
+ int ret;
+
+ ret = __ftrace_modify_caller(&ftrace_graph_call,
+ ftrace_graph_caller,
+ enable);
+
+#ifdef CONFIG_OLD_MCOUNT
+ if (!ret)
+ ret = __ftrace_modify_caller(&ftrace_graph_call_old,
+ ftrace_graph_caller_old,
+ enable);
+#endif
+
+ return ret;
+}
+
+int ftrace_enable_ftrace_graph_caller(void)
+{
+ return ftrace_modify_graph_caller(true);
+}
+
+int ftrace_disable_ftrace_graph_caller(void)
+{
+ return ftrace_modify_graph_caller(false);
+}
+#endif /* CONFIG_DYNAMIC_FTRACE */
+#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
git.openpandora.org / pandora-kernel.git / blobdiff