s390/uprobes: implement arch_uretprobe_is_alive()

Implement s390 specific arch_uretprobe_is_alive() to avoid SIGSEGVs
observed with uretprobes in combination with setjmp/longjmp.

See commit 2dea1d9c38e4 ("powerpc/uprobes: Implement
arch_uretprobe_is_alive()") for more details.

With this implemented all test cases referenced in the above commit
pass.

Reported-by: Ziqian SUN <zsun@redhat.com>
Cc: <stable@vger.kernel.org> # v4.3+
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

diff --git a/arch/s390/kernel/uprobes.c b/arch/s390/kernel/uprobes.c
index d9d1f512f019415ed36912e7afd81156fbd284ae..5007fac01bb5e215392362768898cc829cc121d0 100644 (file)
--- a/arch/s390/kernel/uprobes.c
+++ b/arch/s390/kernel/uprobes.c
@@ -150,6 +150,15 @@ unsigned long arch_uretprobe_hijack_return_addr(unsigned long trampoline,
        return orig;
 }
 
+bool arch_uretprobe_is_alive(struct return_instance *ret, enum rp_check ctx,
+                            struct pt_regs *regs)
+{
+       if (ctx == RP_CHECK_CHAIN_CALL)
+               return user_stack_pointer(regs) <= ret->stack;
+       else
+               return user_stack_pointer(regs) < ret->stack;
+}
+
 /* Instruction Emulation */
 
 static void adjust_psw_addr(psw_t *psw, unsigned long len)