Hello.
On 09-05-2013 18:49, Tony Wu wrote:
schedule_mfi is supposed to be extracted from schedule(), and
is used in thread_saved_pc and get_wchan.
But, after optimization, schedule() is reduced to a sibling
call to __schedule(), and no real frame info can be extracted.
One solution is to compile schedule() with -fno-omit-frame-pointer
and -fno-optimize-sibling-calls, but that will incur performance
degradation.
This patch follows the sibling call and extracts the
schedule_mfi from the __schedule with and without KALLSYMS enabled.
Signed-off-by: Tony Wu <tung7970@xxxxxxxxx>
---
arch/mips/kernel/process.c | 28 ++++++++++++++++++++++++++--
1 file changed, 26 insertions(+), 2 deletions(-)
diff --git a/arch/mips/kernel/process.c b/arch/mips/kernel/process.c
index a794eb5..289ea69 100644
--- a/arch/mips/kernel/process.c
+++ b/arch/mips/kernel/process.c
@@ -314,15 +314,39 @@ err:
static struct mips_frame_info schedule_mfi __read_mostly;
+static unsigned long get___schedule_addr(void)
+{
+#ifdef CONFIG_KALLSYMS
+ return kallsyms_lookup_name("__schedule");
+#else
+ union mips_instruction *ip = (void *)schedule;
+ int max_insns = 8;
+ int i;
+
+ for (i = 0; i < max_insns; i++, ip++) {
+ if (ip->j_format.opcode == j_op)
+ return J_TARGET(ip, ip->j_format.target);
+ }
+ return 0;
+#endif
+}
+
#ifdef's inside function body are frowned upon. Better code it as:
#ifdef CONFIG_KALLSYMS
static unsigned long get___schedule_addr(void)
{
return kallsyms_lookup_name("__schedule");
}
#else
static unsigned long get___schedule_addr(void)
{
union mips_instruction *ip = (void *)schedule;
[...]
return 0;
}
#endif
WBR, Sergei
