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s390/test_unwind: add program check context tests 

Add unwinding from program check handler tests. Unwinder should be able
to unwind through pt_regs stored by program check handler on task stack.

Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
This commit is contained in:
Vasily Gorbik 2019-11-25 14:07:40 +01:00
parent e7409367ab
commit de6921ccbd
1 changed files with 47 additions and 0 deletions
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47
arch/s390/lib/test_unwind.c
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@ -10,6 +10,7 @@
#include <linux/kthread.h>
#include <linux/module.h>
#include <linux/string.h>
#include <linux/kprobes.h>
#include <linux/wait.h>
#include <asm/irq.h>
#include <asm/delay.h>
@ -119,6 +120,7 @@ static struct unwindme *unwindme;
#define UWM_CALLER 0x8 /* Unwind starting from caller. */
#define UWM_SWITCH_STACK 0x10 /* Use CALL_ON_STACK. */
#define UWM_IRQ 0x20 /* Unwind from irq context. */
#define UWM_PGM 0x40 /* Unwind from program check handler. */
static __always_inline unsigned long get_psw_addr(void)
{
@ -130,6 +132,17 @@ static __always_inline unsigned long get_psw_addr(void)
return psw_addr;
}
#ifdef CONFIG_KPROBES
static int pgm_pre_handler(struct kprobe *p, struct pt_regs *regs)
{
struct unwindme *u = unwindme;
u->ret = test_unwind(NULL, (u->flags & UWM_REGS) ? regs : NULL,
(u->flags & UWM_SP) ? u->sp : 0);
return 0;
}
#endif
/* This function may or may not appear in the backtrace. */
static noinline int unwindme_func4(struct unwindme *u)
{
@ -140,6 +153,34 @@ static noinline int unwindme_func4(struct unwindme *u)
wait_event(u->task_wq, kthread_should_park());
kthread_parkme();
return 0;
#ifdef CONFIG_KPROBES
} else if (u->flags & UWM_PGM) {
struct kprobe kp;
int ret;
unwindme = u;
memset(&kp, 0, sizeof(kp));
kp.symbol_name = "do_report_trap";
kp.pre_handler = pgm_pre_handler;
ret = register_kprobe(&kp);
if (ret < 0) {
pr_err("register_kprobe failed %d\n", ret);
return -EINVAL;
}
/*
* trigger specification exception
*/
asm volatile(
" mvcl %%r1,%%r1\n"
"0: nopr %%r7\n"
EX_TABLE(0b, 0b)
:);
unregister_kprobe(&kp);
unwindme = NULL;
return u->ret;
#endif
} else {
struct pt_regs regs;
@ -286,6 +327,12 @@ do { \
TEST(UWM_IRQ | UWM_CALLER | UWM_SP);
TEST(UWM_IRQ | UWM_CALLER | UWM_SP | UWM_REGS);
TEST(UWM_IRQ | UWM_CALLER | UWM_SP | UWM_REGS | UWM_SWITCH_STACK);
#ifdef CONFIG_KPROBES
TEST(UWM_PGM);
TEST(UWM_PGM | UWM_SP);
TEST(UWM_PGM | UWM_REGS);
TEST(UWM_PGM | UWM_SP | UWM_REGS);
#endif
#undef TEST
return ret;