Commit b94c0ebb authored by Heiko Carstens's avatar Heiko Carstens Committed by Vasily Gorbik
Browse files

s390: enable HAVE_ARCH_STACKLEAK 



Add support for the stackleak feature. Whenever the kernel returns to user
space the kernel stack is filled with a poison value.

Enabling this feature is quite expensive: e.g. after instrumenting the
getpid() system call function to have a 4kb stack the result is an
increased runtime of the system call by a factor of 3.

Reviewed-by: default avatarVasily Gorbik <gor@linux.ibm.com>
Signed-off-by: default avatarHeiko Carstens <hca@linux.ibm.com>
Signed-off-by: default avatarVasily Gorbik <gor@linux.ibm.com>
parent 22ca1e77

arch/s390/Kconfig

+1 −0
Original line number Diff line number Diff line
@@ -155,6 +155,7 @@ config S390 
	select HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET

	select HAVE_ARCH_SECCOMP_FILTER

	select HAVE_ARCH_SOFT_DIRTY

	select HAVE_ARCH_STACKLEAK

	select HAVE_ARCH_TRACEHOOK

	select HAVE_ARCH_TRANSPARENT_HUGEPAGE

	select HAVE_ARCH_VMAP_STACK

arch/s390/kernel/entry.S

+10 −0
Original line number Diff line number Diff line
@@ -150,6 +150,12 @@ _LPP_OFFSET = __LC_LPP 
	.endm

#endif



	.macro STACKLEAK_ERASE

#ifdef CONFIG_GCC_PLUGIN_STACKLEAK

	brasl	%r14,stackleak_erase_on_task_stack

#endif

	.endm



	GEN_BR_THUNK %r14



	.section .kprobes.text, "ax"
@@ -300,6 +306,7 @@ ENTRY(system_call) 
	MBEAR	%r2

	lgr	%r3,%r14

	brasl	%r14,__do_syscall

	STACKLEAK_ERASE

	lctlg	%c1,%c1,__LC_USER_ASCE

	mvc	__LC_RETURN_PSW(16),STACK_FRAME_OVERHEAD+__PT_PSW(%r15)

	BPON
@@ -315,6 +322,7 @@ ENDPROC(system_call) 
ENTRY(ret_from_fork)

	lgr	%r3,%r11

	brasl	%r14,__ret_from_fork

	STACKLEAK_ERASE

	lctlg	%c1,%c1,__LC_USER_ASCE

	mvc	__LC_RETURN_PSW(16),STACK_FRAME_OVERHEAD+__PT_PSW(%r15)

	BPON
@@ -375,6 +383,7 @@ ENTRY(pgm_check_handler) 
	brasl	%r14,__do_pgm_check

	tmhh	%r8,0x0001		# returning to user space?

	jno	.Lpgm_exit_kernel

	STACKLEAK_ERASE

	lctlg	%c1,%c1,__LC_USER_ASCE

	BPON

	stpt	__LC_EXIT_TIMER
@@ -440,6 +449,7 @@ ENTRY(\name) 
	mvc	__LC_RETURN_PSW(16),__PT_PSW(%r11)

	tmhh	%r8,0x0001		# returning to user ?

	jno	2f

	STACKLEAK_ERASE

	lctlg	%c1,%c1,__LC_USER_ASCE

	BPON

	stpt	__LC_EXIT_TIMER