There are some magic constant numbers about stack layout in
thread_saved_pc() and get_wchan() function.
I made a patch to eliminate these magic numbers. This patch analyzes
some functions prologue codes in heuristic way at run-time. "ps -l"
(and "MAGIC SYSRQ" feature) works fine with this patch.
---
Atsushi Nemoto
diff -ur linux.sgi/arch/mips/kernel/process.c linux/arch/mips/kernel/process.c
--- linux.sgi/arch/mips/kernel/process.c Sun Aug 5 23:39:09 2001
+++ linux/arch/mips/kernel/process.c Wed Aug 22 14:14:29 2001
@@ -19,6 +19,7 @@
#include <linux/sys.h>
#include <linux/user.h>
#include <linux/a.out.h>
+#include <linux/init.h>
#include <asm/bootinfo.h>
#include <asm/cpu.h>
@@ -31,6 +32,7 @@
#include <asm/io.h>
#include <asm/elf.h>
#include <asm/isadep.h>
+#include <asm/inst.h>
void cpu_idle(void)
{
@@ -196,6 +198,59 @@
#define first_sched ((unsigned long) scheduling_functions_start_here)
#define last_sched ((unsigned long) scheduling_functions_end_here)
+struct mips_frame_info schedule_frame;
+static struct mips_frame_info schedule_timeout_frame;
+static struct mips_frame_info sleep_on_frame;
+static struct mips_frame_info sleep_on_timeout_frame;
+static int mips_frame_info_initialized;
+static int __init get_frame_info(struct mips_frame_info *info, void *func)
+{
+ int i;
+ union mips_instruction *ip = (union mips_instruction *)func;
+ info->pc_offset = -1;
+ info->frame_offset = -1;
+ for (i = 0; i < 128; i++, ip++) {
+ /* if jal, jalr, jr, stop. */
+ if (ip->j_format.opcode == jal_op ||
+ (ip->r_format.opcode == spec_op &&
+ (ip->r_format.func == jalr_op ||
+ ip->r_format.func == jr_op)))
+ break;
+ if (ip->i_format.opcode == sw_op &&
+ ip->i_format.rs == 29) {
+ /* sw $ra, offset($sp) */
+ if (ip->i_format.rt == 31) {
+ if (info->pc_offset != -1)
+ break;
+ info->pc_offset =
+ ip->i_format.simmediate / sizeof(long);
+ }
+ /* sw $s8, offset($sp) */
+ if (ip->i_format.rt == 30) {
+ if (info->frame_offset != -1)
+ break;
+ info->frame_offset =
+ ip->i_format.simmediate / sizeof(long);
+ }
+ }
+ }
+ if (info->pc_offset == -1 || info->frame_offset == -1) {
+ printk("Can't analize prologue code at %p\n", func);
+ info->pc_offset = -1;
+ info->frame_offset = -1;
+ return -1;
+ }
+ return 0;
+}
+void __init frame_info_init(void)
+{
+ mips_frame_info_initialized =
+ !get_frame_info(&schedule_frame, schedule) &&
+ !get_frame_info(&schedule_timeout_frame, schedule_timeout) &&
+ !get_frame_info(&sleep_on_frame, sleep_on) &&
+ !get_frame_info(&sleep_on_timeout_frame, sleep_on_timeout);
+}
+
/* get_wchan - a maintenance nightmare ... */
unsigned long get_wchan(struct task_struct *p)
{
@@ -204,6 +259,8 @@
if (!p || p == current || p->state == TASK_RUNNING)
return 0;
+ if (!mips_frame_info_initialized)
+ return 0;
pc = thread_saved_pc(&p->thread);
if (pc < first_sched || pc >= last_sched) {
return pc;
@@ -220,23 +277,24 @@
goto schedule_timeout_caller;
schedule_caller:
- frame = ((unsigned long *)p->thread.reg30)[9];
- pc = ((unsigned long *)frame)[11];
+ /* schedule_timeout called by interruptible_sleep_on or sleep_on */
+ frame = ((unsigned long *)p->thread.reg30)[schedule_frame.frame_offset];
+ pc = ((unsigned long *)frame)[sleep_on_frame.pc_offset];
return pc;
schedule_timeout_caller:
/* Must be schedule_timeout ... */
- pc = ((unsigned long *)p->thread.reg30)[10];
- frame = ((unsigned long *)p->thread.reg30)[9];
+ pc = ((unsigned long *)p->thread.reg30)[schedule_frame.pc_offset];
+ frame = ((unsigned long *)p->thread.reg30)[schedule_frame.frame_offset];
/* The schedule_timeout frame ... */
- pc = ((unsigned long *)frame)[14];
- frame = ((unsigned long *)frame)[13];
+ pc = ((unsigned long *)frame)[schedule_timeout_frame.pc_offset];
+ frame = ((unsigned long *)frame)[schedule_timeout_frame.frame_offset];
if (pc >= first_sched && pc < last_sched) {
/* schedule_timeout called by interruptible_sleep_on_timeout */
- pc = ((unsigned long *)frame)[11];
- frame = ((unsigned long *)frame)[10];
+ pc = ((unsigned long *)frame)[sleep_on_timeout_frame.pc_offset];
+ frame = ((unsigned long *)frame)[sleep_on_timeout_frame.frame_offset];
}
return pc;
diff -ur linux.sgi/arch/mips/kernel/setup.c linux/arch/mips/kernel/setup.c
--- linux.sgi/arch/mips/kernel/setup.c Sun Aug 5 23:39:15 2001
+++ linux/arch/mips/kernel/setup.c Wed Aug 22 14:26:19 2001
@@ -518,12 +518,14 @@
void malta_setup(void);
void momenco_ocelot_setup(void);
void nino_setup(void);
+ void frame_info_init(void);
unsigned long bootmap_size;
unsigned long start_pfn, max_pfn, first_usable_pfn;
int i;
+ frame_info_init();
#ifdef CONFIG_BLK_DEV_FD
fd_ops = &no_fd_ops;
#endif
diff -ur linux.sgi/include/asm-mips/processor.h linux/include/asm-mips/processor.h
--- linux.sgi/include/asm-mips/processor.h Sun Aug 5 23:41:29 2001
+++ linux/include/asm-mips/processor.h Wed Aug 22 14:14:59 2001
@@ -217,6 +217,11 @@
#define copy_segments(p, mm) do { } while(0)
#define release_segments(mm) do { } while(0)
+struct mips_frame_info {
+ int frame_offset;
+ int pc_offset;
+};
+extern struct mips_frame_info schedule_frame;
/*
* Return saved PC of a blocked thread.
*/
@@ -228,7 +233,9 @@
if (t->reg31 == (unsigned long) ret_from_fork)
return t->reg31;
- return ((unsigned long *)t->reg29)[10];
+ if (schedule_frame.pc_offset < 0)
+ return 0;
+ return ((unsigned long *)t->reg29)[schedule_frame.pc_offset];
}
/*
