@@ -109,6 +109,8 @@ void disable_debug_monitors(enum dbg_active_el el);
void user_rewind_single_step(struct task_struct *task);
void user_fastforward_single_step(struct task_struct *task);
+void user_regs_reset_single_step(struct user_pt_regs *regs,
+ struct task_struct *task);
void kernel_enable_single_step(struct pt_regs *regs);
void kernel_disable_single_step(void);
@@ -141,17 +141,20 @@ postcore_initcall(debug_monitors_init);
/*
* Single step API and exception handling.
*/
-static void set_regs_spsr_ss(struct pt_regs *regs)
+static void set_user_regs_spsr_ss(struct user_pt_regs *regs)
{
regs->pstate |= DBG_SPSR_SS;
}
-NOKPROBE_SYMBOL(set_regs_spsr_ss);
+NOKPROBE_SYMBOL(set_user_regs_spsr_ss);
-static void clear_regs_spsr_ss(struct pt_regs *regs)
+static void clear_user_regs_spsr_ss(struct user_pt_regs *regs)
{
regs->pstate &= ~DBG_SPSR_SS;
}
-NOKPROBE_SYMBOL(clear_regs_spsr_ss);
+NOKPROBE_SYMBOL(clear_user_regs_spsr_ss);
+
+#define set_regs_spsr_ss(r) set_user_regs_spsr_ss(&(r)->user_regs)
+#define clear_regs_spsr_ss(r) clear_user_regs_spsr_ss(&(r)->user_regs)
static DEFINE_SPINLOCK(debug_hook_lock);
static LIST_HEAD(user_step_hook);
@@ -402,6 +405,15 @@ void user_fastforward_single_step(struct task_struct *task)
clear_regs_spsr_ss(task_pt_regs(task));
}
+void user_regs_reset_single_step(struct user_pt_regs *regs,
+ struct task_struct *task)
+{
+ if (test_tsk_thread_flag(task, TIF_SINGLESTEP))
+ set_user_regs_spsr_ss(regs);
+ else
+ clear_user_regs_spsr_ss(regs);
+}
+
/* Kernel API */
void kernel_enable_single_step(struct pt_regs *regs)
{
@@ -1934,8 +1934,8 @@ static int valid_native_regs(struct user_pt_regs *regs)
*/
int valid_user_regs(struct user_pt_regs *regs, struct task_struct *task)
{
- if (!test_tsk_thread_flag(task, TIF_SINGLESTEP))
- regs->pstate &= ~DBG_SPSR_SS;
+ /* https://lore.kernel.org/lkml/20191118131525.GA4180@willie-the-truck */
+ user_regs_reset_single_step(regs, task);
if (is_compat_thread(task_thread_info(task)))
return valid_compat_regs(regs);
@@ -505,8 +505,12 @@ static int restore_sigframe(struct pt_regs *regs,
forget_syscall(regs);
err |= !valid_user_regs(®s->user_regs, current);
- if (err == 0)
+
+ if (err == 0) {
+ /* Make it look like we stepped the sigreturn system call */
+ user_fastforward_single_step(current);
err = parse_user_sigframe(&user, sf);
+ }
if (err == 0 && system_supports_fpsimd()) {
if (!user.fpsimd)