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s390/test_unwind: add CALL_ON_STACK tests 

Add CALL_ON_STACK helper testing. Tests make sure that we can unwind from
switched stack to original one up to task pt_regs (nodat -> task stack).

UWM_SWITCH_STACK could not be used together with UWM_THREAD because
get_stack_info explicitly restricts unwinding to task stack if
task != current.

Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
This commit is contained in:
Vasily Gorbik 2019-11-22 18:22:06 +01:00
parent 4ac24c092b
commit 7868249fbb
1 changed files with 19 additions and 7 deletions
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26
arch/s390/lib/test_unwind.c
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@ -43,7 +43,7 @@ static noinline int test_unwind(struct task_struct *task, struct pt_regs *regs,
int ret = 0;
char *bt;
bt = kmalloc(BT_BUF_SIZE, GFP_KERNEL);
bt = kmalloc(BT_BUF_SIZE, GFP_ATOMIC);
if (!bt) {
pr_err("failed to allocate backtrace buffer\n");
return -ENOMEM;
@ -98,11 +98,12 @@ struct unwindme {
};
/* Values of unwindme.flags. */
#define UWM_DEFAULT 0x0
#define UWM_THREAD 0x1 /* Unwind a separate task. */
#define UWM_REGS 0x2 /* Pass regs to test_unwind(). */
#define UWM_SP 0x4 /* Pass sp to test_unwind(). */
#define UWM_CALLER 0x8 /* Unwind starting from caller. */
#define UWM_DEFAULT 0x0
#define UWM_THREAD 0x1 /* Unwind a separate task. */
#define UWM_REGS 0x2 /* Pass regs to test_unwind(). */
#define UWM_SP 0x4 /* Pass sp to test_unwind(). */
#define UWM_CALLER 0x8 /* Unwind starting from caller. */
#define UWM_SWITCH_STACK 0x10 /* Use CALL_ON_STACK. */
static __always_inline unsigned long get_psw_addr(void)
{
@ -146,7 +147,16 @@ static noinline int unwindme_func3(struct unwindme *u)
/* This function must appear in the backtrace. */
static noinline int unwindme_func2(struct unwindme *u)
{
return unwindme_func3(u);
int rc;
if (u->flags & UWM_SWITCH_STACK) {
preempt_disable();
rc = CALL_ON_STACK(unwindme_func3, S390_lowcore.nodat_stack, 1, u);
preempt_enable();
return rc;
} else {
return unwindme_func3(u);
}
}
/* This function must follow unwindme_func2 in the backtrace. */
@ -215,9 +225,11 @@ do { \
TEST(UWM_DEFAULT);
TEST(UWM_SP);
TEST(UWM_REGS);
TEST(UWM_SWITCH_STACK);
TEST(UWM_SP | UWM_REGS);
TEST(UWM_CALLER | UWM_SP);
TEST(UWM_CALLER | UWM_SP | UWM_REGS);
TEST(UWM_CALLER | UWM_SP | UWM_REGS | UWM_SWITCH_STACK);
TEST(UWM_THREAD);
TEST(UWM_THREAD | UWM_SP);
TEST(UWM_THREAD | UWM_CALLER | UWM_SP);