aboutsummaryrefslogtreecommitdiff
path: root/arch/powerpc/kernel/process.c
diff options
context:
space:
mode:
authorChristophe Leroy <christophe.leroy@c-s.fr>2019-01-31 10:08:52 +0000
committerMichael Ellerman <mpe@ellerman.id.au>2019-02-23 22:31:40 +1100
commit018cce33c5e62dda265df8ae0ddf7f3a3357ad1f (patch)
tree2e441439ad12b6bbf76c0e9d00bc6f0a59a24e0d /arch/powerpc/kernel/process.c
parent054860897cd35a4e9cec953ae955b429e31e74f7 (diff)
downloadlinux-018cce33c5e62dda265df8ae0ddf7f3a3357ad1f.tar.gz
powerpc: prep stack walkers for THREAD_INFO_IN_TASK
[text copied from commit 9bbd4c56b0b6 ("arm64: prep stack walkers for THREAD_INFO_IN_TASK")] When CONFIG_THREAD_INFO_IN_TASK is selected, task stacks may be freed before a task is destroyed. To account for this, the stacks are refcounted, and when manipulating the stack of another task, it is necessary to get/put the stack to ensure it isn't freed and/or re-used while we do so. This patch reworks the powerpc stack walking code to account for this. When CONFIG_THREAD_INFO_IN_TASK is not selected these perform no refcounting, and this should only be a structural change that does not affect behaviour. Acked-by: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr> Reviewed-by: Nicholas Piggin <npiggin@gmail.com> [mpe: Move try_get_task_stack() below tsk == NULL check in show_stack()] Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Diffstat (limited to 'arch/powerpc/kernel/process.c')
-rw-r--r--arch/powerpc/kernel/process.c26
1 files changed, 23 insertions, 3 deletions
diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index 71bad4b6f80d..791bd8ea475d 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -2027,7 +2027,7 @@ int validate_sp(unsigned long sp, struct task_struct *p,
EXPORT_SYMBOL(validate_sp);
-unsigned long get_wchan(struct task_struct *p)
+static unsigned long __get_wchan(struct task_struct *p)
{
unsigned long ip, sp;
int count = 0;
@@ -2053,6 +2053,20 @@ unsigned long get_wchan(struct task_struct *p)
return 0;
}
+unsigned long get_wchan(struct task_struct *p)
+{
+ unsigned long ret;
+
+ if (!try_get_task_stack(p))
+ return 0;
+
+ ret = __get_wchan(p);
+
+ put_task_stack(p);
+
+ return ret;
+}
+
static int kstack_depth_to_print = CONFIG_PRINT_STACK_DEPTH;
void show_stack(struct task_struct *tsk, unsigned long *stack)
@@ -2067,9 +2081,13 @@ void show_stack(struct task_struct *tsk, unsigned long *stack)
int curr_frame = 0;
#endif
- sp = (unsigned long) stack;
if (tsk == NULL)
tsk = current;
+
+ if (!try_get_task_stack(tsk))
+ return;
+
+ sp = (unsigned long) stack;
if (sp == 0) {
if (tsk == current)
sp = current_stack_pointer();
@@ -2081,7 +2099,7 @@ void show_stack(struct task_struct *tsk, unsigned long *stack)
printk("Call Trace:\n");
do {
if (!validate_sp(sp, tsk, STACK_FRAME_OVERHEAD))
- return;
+ break;
stack = (unsigned long *) sp;
newsp = stack[0];
@@ -2121,6 +2139,8 @@ void show_stack(struct task_struct *tsk, unsigned long *stack)
sp = newsp;
} while (count++ < kstack_depth_to_print);
+
+ put_task_stack(tsk);
}
#ifdef CONFIG_PPC64