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authorJeff Dike <jdike@addtoit.com>2008-02-04 22:30:36 -0800
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2008-02-05 09:44:25 -0800
commitc11274655558e72d8d4a598c0077874c094d97d5 (patch)
treec7d13b5aeb4994a1c03ec6a5edd723ba06fd94da
parentc9a3072d13e4b8a6549ecc1db6390a55c7ee2ddf (diff)
uml: implement get_wchan
Implement get_wchan - the algorithm is similar to x86. It starts with the stack pointer of the process in question and looks above that for addresses that are kernel text. The second one which isn't in the scheduler is the one that's returned. The first one is ignored because that will be UML's own context switching routine. Signed-off-by: Jeff Dike <jdike@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--arch/um/kernel/process.c35
-rw-r--r--include/asm-um/processor-generic.h2
2 files changed, 36 insertions, 1 deletions
diff --git a/arch/um/kernel/process.c b/arch/um/kernel/process.c
index 0eae00b3e58..c7ea7f2a894 100644
--- a/arch/um/kernel/process.c
+++ b/arch/um/kernel/process.c
@@ -459,3 +459,38 @@ unsigned long arch_align_stack(unsigned long sp)
return sp & ~0xf;
}
#endif
+
+unsigned long get_wchan(struct task_struct *p)
+{
+ unsigned long stack_page, sp, ip;
+ bool seen_sched = 0;
+
+ if ((p == NULL) || (p == current) || (p->state == TASK_RUNNING))
+ return 0;
+
+ stack_page = (unsigned long) task_stack_page(p);
+ /* Bail if the process has no kernel stack for some reason */
+ if (stack_page == 0)
+ return 0;
+
+ sp = p->thread.switch_buf->JB_SP;
+ /*
+ * Bail if the stack pointer is below the bottom of the kernel
+ * stack for some reason
+ */
+ if (sp < stack_page)
+ return 0;
+
+ while (sp < stack_page + THREAD_SIZE) {
+ ip = *((unsigned long *) sp);
+ if (in_sched_functions(ip))
+ /* Ignore everything until we're above the scheduler */
+ seen_sched = 1;
+ else if (kernel_text_address(ip) && seen_sched)
+ return ip;
+
+ sp += sizeof(unsigned long);
+ }
+
+ return 0;
+}
diff --git a/include/asm-um/processor-generic.h b/include/asm-um/processor-generic.h
index 78c0599cc80..057a76d4156 100644
--- a/include/asm-um/processor-generic.h
+++ b/include/asm-um/processor-generic.h
@@ -128,6 +128,6 @@ extern struct cpuinfo_um cpu_data[];
#define KSTK_REG(tsk, reg) get_thread_reg(reg, &tsk->thread.switch_buf)
-#define get_wchan(p) (0)
+extern unsigned long get_wchan(struct task_struct *p);
#endif