On 05/12/2010 06:23 AM, Wu Zhangjin wrote:
From: Wu Zhangjin<wuzhangjin@xxxxxxxxx>
This patch adds an inline function in_module() to check which space the
instruction pointer in, kernel space or module space.
Note: This may not work when the kernel is compiled with -msym32.
The kernel is always compiled with -msym32, so the patch is a bit pointless.
Signed-off-by: Wu Zhangjin<wuzhangjin@xxxxxxxxx>
---
arch/mips/kernel/ftrace.c | 17 ++++++++++++++---
1 files changed, 14 insertions(+), 3 deletions(-)
diff --git a/arch/mips/kernel/ftrace.c b/arch/mips/kernel/ftrace.c
index 628e90b..37f15b6 100644
--- a/arch/mips/kernel/ftrace.c
+++ b/arch/mips/kernel/ftrace.c
@@ -17,6 +17,17 @@
#include<asm/cacheflush.h>
#include<asm/uasm.h>
+/*
+ * If the Instruction Pointer is in module space (0xc0000000), return true;
+ * otherwise, it is in kernel space (0x80000000), return false.
+ *
+ * FIXME: This may not work when the kernel is compiled with -msym32.
+ */
+static inline int in_module(unsigned long ip)
+{
+ return ip& 0x40000000;
+}
+
How about (untested):
static inline int in_module(unsigned long ip)
{
return ip < _text || ip > _etext;
}
But why do we even care? Can't we just probe the function prologue and
determine from that what needs to be done?
David Daney
#ifdef CONFIG_DYNAMIC_FTRACE
#define JAL 0x0c000000 /* jump& link: ip --> ra, jump to target */
@@ -78,7 +89,7 @@ int ftrace_make_nop(struct module *mod,
* We have compiled module with -mlong-calls, but compiled the kernel
* without it, we need to cope with them respectively.
*/
- if (ip& 0x40000000) {
+ if (in_module(ip)) {
#if defined(KBUILD_MCOUNT_RA_ADDRESS)&& defined(CONFIG_32BIT)
/*
* lui v1, hi_16bit_of_mcount --> b 1f (0x10000005)
@@ -117,7 +128,7 @@ int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
unsigned long ip = rec->ip;
/* ip, module: 0xc0000000, kernel: 0x80000000 */
- new = (ip& 0x40000000) ? insn_lui_v1_hi16_mcount : insn_jal_ftrace_caller;
+ new = in_module(ip) ? insn_lui_v1_hi16_mcount : insn_jal_ftrace_caller;
return ftrace_modify_code(ip, new);
}
@@ -188,7 +199,7 @@ unsigned long ftrace_get_parent_addr(unsigned long self_addr,
* instruction "lui v1, hi_16bit_of_mcount"(offset is 20), but for
* kernel, move to the instruction "move ra, at"(offset is 12)
*/
- ip = self_addr - ((self_addr& 0x40000000) ? 20 : 12);
+ ip = self_addr - (in_module(self_addr) ? 20 : 12);
/*
* search the text until finding the non-store instruction or "s{d,w}
