Commit 59da2139 authored by Martin Schwidefsky's avatar Martin Schwidefsky
Browse files

[S390] fix system call parameter functions. 



syscall_get_nr() currently returns a valid result only if the call
chain of the traced process includes do_syscall_trace_enter(). But
collect_syscall() can be called for any sleeping task, the result of
syscall_get_nr() in general is completely bogus.

To make syscall_get_nr() work for any sleeping task the traps field
in pt_regs is replace with svcnr - the system call number the process
is executing. If svcnr == 0 the process is not on a system call path.

The syscall_get_arguments and syscall_set_arguments use regs->gprs[2]
for the first system call parameter. This is incorrect since gprs[2]
may have been overwritten with the system call number if the call
chain includes do_syscall_trace_enter. Use regs->orig_gprs2 instead.

Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
parent ed313489

arch/s390/include/asm/ptrace.h

+1 −1
Original line number Diff line number Diff line
@@ -321,8 +321,8 @@ struct pt_regs 
	psw_t psw;

	unsigned long gprs[NUM_GPRS];

	unsigned long orig_gpr2;

	unsigned short svcnr;

	unsigned short ilc;

	unsigned short trap;

};

#endif

arch/s390/include/asm/syscall.h

+16 −12
Original line number Diff line number Diff line
@@ -17,9 +17,7 @@ 
static inline long syscall_get_nr(struct task_struct *task,

				  struct pt_regs *regs)

{

	if (regs->trap != __LC_SVC_OLD_PSW)

		return -1;

	return regs->gprs[2];

	return regs->svcnr ? regs->svcnr : -1;

}



static inline void syscall_rollback(struct task_struct *task,
@@ -52,18 +50,20 @@ static inline void syscall_get_arguments(struct task_struct *task, 
					 unsigned int i, unsigned int n,

					 unsigned long *args)

{

	unsigned long mask = -1UL;



	BUG_ON(i + n > 6);

#ifdef CONFIG_COMPAT

	if (test_tsk_thread_flag(task, TIF_31BIT)) {

		if (i + n == 6)

			args[--n] = (u32) regs->args[0];

		while (n-- > 0)

			args[n] = (u32) regs->gprs[2 + i + n];

	}

	if (test_tsk_thread_flag(task, TIF_31BIT))

		mask = 0xffffffff;

#endif

	if (i + n == 6)

		args[--n] = regs->args[0];

	memcpy(args, &regs->gprs[2 + i], n * sizeof(args[0]));

		args[--n] = regs->args[0] & mask;

	while (n-- > 0)

		if (i + n > 0)

			args[n] = regs->gprs[2 + i + n] & mask;

	if (i == 0)

		args[0] = regs->orig_gpr2 & mask;

}



static inline void syscall_set_arguments(struct task_struct *task,
@@ -74,7 +74,11 @@ static inline void syscall_set_arguments(struct task_struct *task, 
	BUG_ON(i + n > 6);

	if (i + n == 6)

		regs->args[0] = args[--n];

	memcpy(&regs->gprs[2 + i], args, n * sizeof(args[0]));

	while (n-- > 0)

		if (i + n > 0)

			regs->gprs[2 + i + n] = args[n];

	if (i == 0)

		regs->orig_gpr2 = args[0];

}



#endif	/* _ASM_SYSCALL_H */

arch/s390/kernel/asm-offsets.c

+1 −1
Original line number Diff line number Diff line
@@ -32,7 +32,7 @@ int main(void) 
	DEFINE(__PT_GPRS, offsetof(struct pt_regs, gprs));

	DEFINE(__PT_ORIG_GPR2, offsetof(struct pt_regs, orig_gpr2));

	DEFINE(__PT_ILC, offsetof(struct pt_regs, ilc));

	DEFINE(__PT_TRAP, offsetof(struct pt_regs, trap));

	DEFINE(__PT_SVCNR, offsetof(struct pt_regs, svcnr));

	DEFINE(__PT_SIZE, sizeof(struct pt_regs));

	BLANK();

	DEFINE(__SF_BACKCHAIN, offsetof(struct stack_frame, back_chain));

arch/s390/kernel/compat_signal.c

+1 −1
Original line number Diff line number Diff line
@@ -340,7 +340,7 @@ static int restore_sigregs32(struct pt_regs *regs,_sigregs32 __user *sregs) 
		return err;



	restore_fp_regs(&current->thread.fp_regs);

	regs->trap = -1;	/* disable syscall checks */

	regs->svcnr = 0;	/* disable syscall checks */

	return 0;

}

arch/s390/kernel/entry.S

+11 −10
Original line number Diff line number Diff line
@@ -46,7 +46,7 @@ SP_R14 = STACK_FRAME_OVERHEAD + __PT_GPRS + 56 
SP_R15	     =	STACK_FRAME_OVERHEAD + __PT_GPRS + 60

SP_ORIG_R2   =	STACK_FRAME_OVERHEAD + __PT_ORIG_GPR2

SP_ILC	     =	STACK_FRAME_OVERHEAD + __PT_ILC

SP_TRAP      =	STACK_FRAME_OVERHEAD + __PT_TRAP

SP_SVCNR     =	STACK_FRAME_OVERHEAD + __PT_SVCNR

SP_SIZE      =	STACK_FRAME_OVERHEAD + __PT_SIZE



_TIF_WORK_SVC = (_TIF_SIGPENDING | _TIF_NOTIFY_RESUME | _TIF_NEED_RESCHED | \
@@ -183,11 +183,10 @@ STACK_SIZE = 1 << STACK_SHIFT 
	.macro	CREATE_STACK_FRAME psworg,savearea

	s	%r15,BASED(.Lc_spsize)	# make room for registers & psw

	mvc	SP_PSW(8,%r15),0(%r12)	# move user PSW to stack

	la	%r12,\psworg

	st	%r2,SP_ORIG_R2(%r15)	# store original content of gpr 2

	icm	%r12,12,__LC_SVC_ILC

	icm	%r12,3,__LC_SVC_ILC

	stm	%r0,%r11,SP_R0(%r15)	# store gprs %r0-%r11 to kernel stack

	st	%r12,SP_ILC(%r15)

	st	%r12,SP_SVCNR(%r15)

	mvc	SP_R12(16,%r15),\savearea # move %r12-%r15 to stack

	la	%r12,0

	st	%r12,__SF_BACKCHAIN(%r15)	# clear back chain
@@ -264,16 +263,17 @@ sysc_update: 
#endif

sysc_do_svc:

	l	%r9,__LC_THREAD_INFO	# load pointer to thread_info struct

	sla	%r7,2			# *4 and test for svc 0

	ltr	%r7,%r7			# test for svc 0

	bnz	BASED(sysc_nr_ok)	# svc number > 0

	# svc 0: system call number in %r1

	cl	%r1,BASED(.Lnr_syscalls)

	bnl	BASED(sysc_nr_ok)

	lr	%r7,%r1 	  # copy svc number to %r7

	sla	%r7,2		  # *4

sysc_nr_ok:

	mvc	SP_ARGS(4,%r15),SP_R7(%r15)

sysc_do_restart:

	sth	%r7,SP_SVCNR(%r15)

	sll	%r7,2		  # svc number *4

	l	%r8,BASED(.Lsysc_table)

	tm	__TI_flags+3(%r9),(_TIF_SYSCALL_TRACE|_TIF_SYSCALL_AUDIT)

	l	%r8,0(%r7,%r8)	  # get system call addr.
@@ -376,7 +376,6 @@ sysc_notify_resume: 
sysc_restart:

	ni	__TI_flags+3(%r9),255-_TIF_RESTART_SVC # clear TIF_RESTART_SVC

	l	%r7,SP_R2(%r15) 	# load new svc number

	sla	%r7,2

	mvc	SP_R2(4,%r15),SP_ORIG_R2(%r15) # restore first argument

	lm	%r2,%r6,SP_R2(%r15)	# load svc arguments

	b	BASED(sysc_do_restart)	# restart svc
@@ -386,7 +385,8 @@ sysc_restart: 
#

sysc_singlestep:

	ni	__TI_flags+3(%r9),255-_TIF_SINGLE_STEP # clear TIF_SINGLE_STEP

	mvi	SP_TRAP+1(%r15),0x28	# set trap indication to pgm check

	mvi	SP_SVCNR(%r15),0xff	# set trap indication to pgm check

	mvi	SP_SVCNR+1(%r15),0xff

	la	%r2,SP_PTREGS(%r15)	# address of register-save area

	l	%r1,BASED(.Lhandle_per)	# load adr. of per handler

	la	%r14,BASED(sysc_return)	# load adr. of system return
@@ -407,7 +407,7 @@ sysc_tracesys: 
	bnl	BASED(sysc_tracenogo)

	l	%r8,BASED(.Lsysc_table)

	lr	%r7,%r2

	sll	%r7,2			# *4

	sll	%r7,2			# svc number *4

	l	%r8,0(%r7,%r8)

sysc_tracego:

	lm	%r3,%r6,SP_R3(%r15)
@@ -586,7 +586,8 @@ pgm_svcper: 
# per was called from kernel, must be kprobes

#

kernel_per:

	mvi	SP_TRAP+1(%r15),0x28	# set trap indication to pgm check

	mvi	SP_SVCNR(%r15),0xff	# set trap indication to pgm check

	mvi	SP_SVCNR+1(%r15),0xff

	la	%r2,SP_PTREGS(%r15)	# address of register-save area

	l	%r1,BASED(.Lhandle_per)	# load adr. of per handler

	la	%r14,BASED(sysc_restore)# load adr. of system return

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