Commit 657480d9 authored by Sven Schnelle's avatar Sven Schnelle Committed by Vasily Gorbik
Browse files

s390: support KPROBES_ON_FTRACE 



Instead of using our own kprobes-on-ftrace handling convert the
code to support KPROBES_ON_FTRACE.

Signed-off-by: default avatarSven Schnelle <svens@linux.ibm.com>
Signed-off-by: default avatarVasily Gorbik <gor@linux.ibm.com>
parent 5f490a52

Documentation/features/debug/kprobes-on-ftrace/arch-support.txt

+1 −1
Original line number Diff line number Diff line
@@ -24,7 +24,7 @@ 
    |      parisc: |  ok  |

    |     powerpc: |  ok  |

    |       riscv: | TODO |

    |        s390: | TODO |

    |        s390: |  ok  |

    |          sh: | TODO |

    |       sparc: | TODO |

    |          um: | TODO |

arch/s390/Kconfig

+1 −0
Original line number Diff line number Diff line
@@ -156,6 +156,7 @@ config S390 
	select HAVE_KERNEL_UNCOMPRESSED

	select HAVE_KERNEL_XZ

	select HAVE_KPROBES

	select HAVE_KPROBES_ON_FTRACE

	select HAVE_KRETPROBES

	select HAVE_KVM

	select HAVE_LIVEPATCH

arch/s390/include/asm/kprobes.h

+0 −1
Original line number Diff line number Diff line
@@ -54,7 +54,6 @@ typedef u16 kprobe_opcode_t; 
struct arch_specific_insn {

	/* copy of original instruction */

	kprobe_opcode_t *insn;

	unsigned int is_ftrace_insn : 1;

};



struct prev_kprobe {

arch/s390/kernel/ftrace.c

+46 −34
Original line number Diff line number Diff line
@@ -72,15 +72,6 @@ static inline void ftrace_generate_orig_insn(struct ftrace_insn *insn) 
#endif

}



static inline int is_kprobe_on_ftrace(struct ftrace_insn *insn)

{

#ifdef CONFIG_KPROBES

	if (insn->opc == BREAKPOINT_INSTRUCTION)

		return 1;

#endif

	return 0;

}



static inline void ftrace_generate_kprobe_nop_insn(struct ftrace_insn *insn)

{

#ifdef CONFIG_KPROBES
@@ -114,16 +105,6 @@ int ftrace_make_nop(struct module *mod, struct dyn_ftrace *rec, 
		/* Initial code replacement */

		ftrace_generate_orig_insn(&orig);

		ftrace_generate_nop_insn(&new);

	} else if (is_kprobe_on_ftrace(&old)) {

		/*

		 * If we find a breakpoint instruction, a kprobe has been

		 * placed at the beginning of the function. We write the

		 * constant KPROBE_ON_FTRACE_NOP into the remaining four

		 * bytes of the original instruction so that the kprobes

		 * handler can execute a nop, if it reaches this breakpoint.

		 */

		ftrace_generate_kprobe_call_insn(&orig);

		ftrace_generate_kprobe_nop_insn(&new);

	} else {

		/* Replace ftrace call with a nop. */

		ftrace_generate_call_insn(&orig, rec->ip);
@@ -142,21 +123,10 @@ int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr) 


	if (probe_kernel_read(&old, (void *) rec->ip, sizeof(old)))

		return -EFAULT;

	if (is_kprobe_on_ftrace(&old)) {

		/*

		 * If we find a breakpoint instruction, a kprobe has been

		 * placed at the beginning of the function. We write the

		 * constant KPROBE_ON_FTRACE_CALL into the remaining four

		 * bytes of the original instruction so that the kprobes

		 * handler can execute a brasl if it reaches this breakpoint.

		 */

		ftrace_generate_kprobe_nop_insn(&orig);

		ftrace_generate_kprobe_call_insn(&new);

	} else {

	/* Replace nop with an ftrace call. */

	ftrace_generate_nop_insn(&orig);

	ftrace_generate_call_insn(&new, rec->ip);

	}



	/* Verify that the to be replaced code matches what we expect. */

	if (memcmp(&orig, &old, sizeof(old)))

		return -EINVAL;
@@ -241,3 +211,45 @@ int ftrace_disable_ftrace_graph_caller(void) 
}



#endif /* CONFIG_FUNCTION_GRAPH_TRACER */



#ifdef CONFIG_KPROBES_ON_FTRACE

void kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip,

		struct ftrace_ops *ops, struct pt_regs *regs)

{

	struct kprobe_ctlblk *kcb;

	struct kprobe *p = get_kprobe((kprobe_opcode_t *)ip);



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

		return;



	if (kprobe_running()) {

		kprobes_inc_nmissed_count(p);

		return;

	}



	__this_cpu_write(current_kprobe, p);



	kcb = get_kprobe_ctlblk();

	kcb->kprobe_status = KPROBE_HIT_ACTIVE;



	instruction_pointer_set(regs, ip);



	if (!p->pre_handler || !p->pre_handler(p, regs)) {



		instruction_pointer_set(regs, ip + MCOUNT_INSN_SIZE);



		if (unlikely(p->post_handler)) {

			kcb->kprobe_status = KPROBE_HIT_SSDONE;

			p->post_handler(p, regs, 0);

		}

	}

	__this_cpu_write(current_kprobe, NULL);

}

NOKPROBE_SYMBOL(kprobe_ftrace_handler);



int arch_prepare_kprobe_ftrace(struct kprobe *p)

{

	p->ainsn.insn = NULL;

	return 0;

}

#endif

arch/s390/kernel/kprobes.c

+5 −56
Original line number Diff line number Diff line
@@ -56,20 +56,9 @@ struct kprobe_insn_cache kprobe_s390_insn_slots = { 


static void copy_instruction(struct kprobe *p)

{

	unsigned long ip = (unsigned long) p->addr;

	s64 disp, new_disp;

	u64 addr, new_addr;



	if (ftrace_location(ip) == ip) {

		/*

		 * If kprobes patches the instruction that is morphed by

		 * ftrace make sure that kprobes always sees the branch

		 * "jg .+24" that skips the mcount block or the "brcl 0,0"

		 * in case of hotpatch.

		 */

		ftrace_generate_nop_insn((struct ftrace_insn *)p->ainsn.insn);

		p->ainsn.is_ftrace_insn = 1;

	} else

	memcpy(p->ainsn.insn, p->addr, insn_length(*p->addr >> 8));

	p->opcode = p->ainsn.insn[0];

	if (!probe_is_insn_relative_long(p->ainsn.insn))
@@ -136,11 +125,6 @@ int arch_prepare_kprobe(struct kprobe *p) 
}

NOKPROBE_SYMBOL(arch_prepare_kprobe);



int arch_check_ftrace_location(struct kprobe *p)

{

	return 0;

}



struct swap_insn_args {

	struct kprobe *p;

	unsigned int arm_kprobe : 1;
@@ -149,28 +133,11 @@ struct swap_insn_args { 
static int swap_instruction(void *data)

{

	struct swap_insn_args *args = data;

	struct ftrace_insn new_insn, *insn;

	struct kprobe *p = args->p;

	size_t len;



	new_insn.opc = args->arm_kprobe ? BREAKPOINT_INSTRUCTION : p->opcode;

	len = sizeof(new_insn.opc);

	if (!p->ainsn.is_ftrace_insn)

		goto skip_ftrace;

	len = sizeof(new_insn);

	insn = (struct ftrace_insn *) p->addr;

	if (args->arm_kprobe) {

		if (is_ftrace_nop(insn))

			new_insn.disp = KPROBE_ON_FTRACE_NOP;

		else

			new_insn.disp = KPROBE_ON_FTRACE_CALL;

	} else {

		ftrace_generate_call_insn(&new_insn, (unsigned long)p->addr);

		if (insn->disp == KPROBE_ON_FTRACE_NOP)

			ftrace_generate_nop_insn(&new_insn);

	}

skip_ftrace:

	s390_kernel_write(p->addr, &new_insn, len);

	u16 opc;



	opc = args->arm_kprobe ? BREAKPOINT_INSTRUCTION : p->opcode;

	s390_kernel_write(p->addr, &opc, sizeof(opc));

	return 0;

}

NOKPROBE_SYMBOL(swap_instruction);
@@ -464,24 +431,6 @@ static void resume_execution(struct kprobe *p, struct pt_regs *regs) 
	unsigned long ip = regs->psw.addr;

	int fixup = probe_get_fixup_type(p->ainsn.insn);



	/* Check if the kprobes location is an enabled ftrace caller */

	if (p->ainsn.is_ftrace_insn) {

		struct ftrace_insn *insn = (struct ftrace_insn *) p->addr;

		struct ftrace_insn call_insn;



		ftrace_generate_call_insn(&call_insn, (unsigned long) p->addr);

		/*

		 * A kprobe on an enabled ftrace call site actually single

		 * stepped an unconditional branch (ftrace nop equivalent).

		 * Now we need to fixup things and pretend that a brasl r0,...

		 * was executed instead.

		 */

		if (insn->disp == KPROBE_ON_FTRACE_CALL) {

			ip += call_insn.disp * 2 - MCOUNT_INSN_SIZE;

			regs->gprs[0] = (unsigned long)p->addr + sizeof(*insn);

		}

	}



	if (fixup & FIXUP_PSW_NORMAL)

		ip += (unsigned long) p->addr - (unsigned long) p->ainsn.insn;