Commit 1389f179 authored by Heiko Carstens's avatar Heiko Carstens Committed by Vasily Gorbik
Browse files

s390/ftrace: fix arch_ftrace_get_regs implementation 



arch_ftrace_get_regs is supposed to return a struct pt_regs pointer
only if the pt_regs structure contains all register contents, which
means it must have been populated when created via ftrace_regs_caller.

If it was populated via ftrace_caller the contents are not complete
(the psw mask part is missing), and therefore a NULL pointer needs be
returned.

The current code incorrectly always returns a struct pt_regs pointer.

Fix this by adding another pt_regs flag which indicates if the
contents are complete, and fix arch_ftrace_get_regs accordingly.

Fixes: 89497968 ("s390/ftrace: provide separate ftrace_caller/ftrace_regs_caller implementations")
Reported-by: default avatarChristophe Leroy <christophe.leroy@csgroup.eu>
Reported-by: default avatarNaveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Reviewed-by: default avatarSven Schnelle <svens@linux.ibm.com>
Acked-by: default avatarIlya Leoshkevich <iii@linux.ibm.com>
Signed-off-by: default avatarHeiko Carstens <hca@linux.ibm.com>
Signed-off-by: default avatarVasily Gorbik <gor@linux.ibm.com>
parent 9fa881f7

arch/s390/include/asm/ftrace.h

+6 −4
Original line number Diff line number Diff line
@@ -47,15 +47,17 @@ struct ftrace_regs { 


static __always_inline struct pt_regs *arch_ftrace_get_regs(struct ftrace_regs *fregs)

{

	return &fregs->regs;

	struct pt_regs *regs = &fregs->regs;



	if (test_pt_regs_flag(regs, PIF_FTRACE_FULL_REGS))

		return regs;

	return NULL;

}



static __always_inline void ftrace_instruction_pointer_set(struct ftrace_regs *fregs,

							   unsigned long ip)

{

	struct pt_regs *regs = arch_ftrace_get_regs(fregs);



	regs->psw.addr = ip;

	fregs->regs.psw.addr = ip;

}



/*

arch/s390/include/asm/ptrace.h

+2 −0
Original line number Diff line number Diff line
@@ -15,11 +15,13 @@ 
#define PIF_EXECVE_PGSTE_RESTART	1	/* restart execve for PGSTE binaries */

#define PIF_SYSCALL_RET_SET		2	/* return value was set via ptrace */

#define PIF_GUEST_FAULT			3	/* indicates program check in sie64a */

#define PIF_FTRACE_FULL_REGS		4	/* all register contents valid (ftrace) */



#define _PIF_SYSCALL			BIT(PIF_SYSCALL)

#define _PIF_EXECVE_PGSTE_RESTART	BIT(PIF_EXECVE_PGSTE_RESTART)

#define _PIF_SYSCALL_RET_SET		BIT(PIF_SYSCALL_RET_SET)

#define _PIF_GUEST_FAULT		BIT(PIF_GUEST_FAULT)

#define _PIF_FTRACE_FULL_REGS		BIT(PIF_FTRACE_FULL_REGS)



#ifndef __ASSEMBLY__

arch/s390/kernel/ftrace.c

+1 −1
Original line number Diff line number Diff line
@@ -326,7 +326,7 @@ void kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip, 


	regs = ftrace_get_regs(fregs);

	p = get_kprobe((kprobe_opcode_t *)ip);

	if (unlikely(!p) || kprobe_disabled(p))

	if (!regs || unlikely(!p) || kprobe_disabled(p))

		goto out;



	if (kprobe_running()) {

arch/s390/kernel/mcount.S

+9 −0
Original line number Diff line number Diff line
@@ -27,6 +27,7 @@ ENDPROC(ftrace_stub) 
#define STACK_PTREGS_GPRS	(STACK_PTREGS + __PT_GPRS)

#define STACK_PTREGS_PSW	(STACK_PTREGS + __PT_PSW)

#define STACK_PTREGS_ORIG_GPR2	(STACK_PTREGS + __PT_ORIG_GPR2)

#define STACK_PTREGS_FLAGS	(STACK_PTREGS + __PT_FLAGS)

#ifdef __PACK_STACK

/* allocate just enough for r14, r15 and backchain */

#define TRACED_FUNC_FRAME_SIZE	24
@@ -57,6 +58,14 @@ ENDPROC(ftrace_stub) 
	.if \allregs == 1

	stg	%r14,(STACK_PTREGS_PSW)(%r15)

	stosm	(STACK_PTREGS_PSW)(%r15),0

#ifdef CONFIG_HAVE_MARCH_Z10_FEATURES

	mvghi	STACK_PTREGS_FLAGS(%r15),_PIF_FTRACE_FULL_REGS

#else

	lghi	%r14,_PIF_FTRACE_FULL_REGS

	stg	%r14,STACK_PTREGS_FLAGS(%r15)

#endif

	.else

	xc	STACK_PTREGS_FLAGS(8,%r15),STACK_PTREGS_FLAGS(%r15)

	.endif



	lg	%r14,(__SF_GPRS+8*8)(%r1)	# restore original return address