Commit 062e5279 authored by Heiko Carstens's avatar Heiko Carstens
Browse files

s390/mm: add debug user asce support 



Verify on exit to user space that always
- the primary ASCE (cr1) is set to kernel ASCE
- the secondary ASCE (cr7) is set to user ASCE

If this is not the case: panic since something went terribly wrong.

Reviewed-by: default avatarSven Schnelle <svens@linux.ibm.com>
Signed-off-by: default avatarHeiko Carstens <hca@linux.ibm.com>
parent 0290c9e3

arch/s390/Kconfig.debug

+8 −0
Original line number Diff line number Diff line
@@ -5,3 +5,11 @@ config TRACE_IRQFLAGS_SUPPORT 


config EARLY_PRINTK

	def_bool y



config DEBUG_USER_ASCE

	bool "Debug User ASCE"

	help

	  Check on exit to user space that address space control

	  elements are setup correctly.



	  If unsure, say N.

arch/s390/configs/debug_defconfig

+1 −0
Original line number Diff line number Diff line
@@ -826,6 +826,7 @@ CONFIG_FTRACE_SYSCALLS=y 
CONFIG_BLK_DEV_IO_TRACE=y

CONFIG_BPF_KPROBE_OVERRIDE=y

CONFIG_HIST_TRIGGERS=y

CONFIG_DEBUG_USER_ASCE=y

CONFIG_NOTIFIER_ERROR_INJECTION=m

CONFIG_NETDEV_NOTIFIER_ERROR_INJECT=m

CONFIG_FAULT_INJECTION=y

arch/s390/include/asm/uaccess.h

+2 −0
Original line number Diff line number Diff line
@@ -18,6 +18,8 @@ 
#include <asm/extable.h>

#include <asm/facility.h>



void debug_user_asce(void);



static inline int __range_ok(unsigned long addr, unsigned long size)

{

	return 1;

arch/s390/kernel/entry.S

+8 −0
Original line number Diff line number Diff line
@@ -90,6 +90,12 @@ _LPP_OFFSET = __LC_LPP 
#endif

	.endm



	.macro	DEBUG_USER_ASCE

#ifdef CONFIG_DEBUG_USER_ASCE

	brasl	%r14,debug_user_asce

#endif

	.endm



	.macro	CHECK_VMAP_STACK savearea,oklabel

#ifdef CONFIG_VMAP_STACK

	lgr	%r14,%r15
@@ -428,6 +434,7 @@ ENTRY(system_call) 
	jnz	.Lsysc_work

	TSTMSK	__TI_flags(%r12),_TIF_WORK

	jnz	.Lsysc_work			# check for work

	DEBUG_USER_ASCE

	lctlg	%c1,%c1,__LC_USER_ASCE

	BPEXIT	__TI_flags(%r12),_TIF_ISOLATE_BP

	TSTMSK	__LC_CPU_FLAGS, _CIF_FPU
@@ -793,6 +800,7 @@ ENTRY(io_int_handler) 
	mvc	__LC_RETURN_PSW(16),__PT_PSW(%r11)

	tm	__PT_PSW+1(%r11),0x01	# returning to user ?

	jno	.Lio_exit_kernel

	DEBUG_USER_ASCE

	lctlg	%c1,%c1,__LC_USER_ASCE

	BPEXIT	__TI_flags(%r12),_TIF_ISOLATE_BP

	stpt	__LC_EXIT_TIMER

arch/s390/lib/uaccess.c

+16 −0
Original line number Diff line number Diff line
@@ -16,6 +16,22 @@ 
#include <asm/mmu_context.h>

#include <asm/facility.h>



#ifdef CONFIG_DEBUG_USER_ASCE

void debug_user_asce(void)

{

	unsigned long cr1, cr7;



	__ctl_store(cr1, 1, 1);

	__ctl_store(cr7, 7, 7);

	if (cr1 == S390_lowcore.kernel_asce && cr7 == S390_lowcore.user_asce)

		return;

	panic("incorrect ASCE on kernel exit\n"

	      "cr1:    %016lx cr7:  %016lx\n"

	      "kernel: %016llx user: %016llx\n",

	      cr1, cr7, S390_lowcore.kernel_asce, S390_lowcore.user_asce);

}

#endif /*CONFIG_DEBUG_USER_ASCE */



#ifndef CONFIG_HAVE_MARCH_Z10_FEATURES

static DEFINE_STATIC_KEY_FALSE(have_mvcos);