[linux-block.git] / arch / s390 / kernel / jump_label.c

// SPDX-License-Identifier: GPL-2.0
/*
 * Jump label s390 support
 *
 * Copyright IBM Corp. 2011
 * Author(s): Jan Glauber <jang@linux.vnet.ibm.com>
 */
#include <linux/uaccess.h>
#include <linux/jump_label.h>
#include <linux/module.h>
#include <asm/text-patching.h>
#include <asm/ipl.h>

struct insn {
	u16 opcode;
	s32 offset;
} __packed;

static void jump_label_make_nop(struct jump_entry *entry, struct insn *insn)
{
	/* brcl 0,offset */
	insn->opcode = 0xc004;
	insn->offset = (jump_entry_target(entry) - jump_entry_code(entry)) >> 1;
}

static void jump_label_make_branch(struct jump_entry *entry, struct insn *insn)
{
	/* brcl 15,offset */
	insn->opcode = 0xc0f4;
	insn->offset = (jump_entry_target(entry) - jump_entry_code(entry)) >> 1;
}

static void jump_label_bug(struct jump_entry *entry, struct insn *expected,
			   struct insn *new)
{
	unsigned char *ipc = (unsigned char *)jump_entry_code(entry);
	unsigned char *ipe = (unsigned char *)expected;
	unsigned char *ipn = (unsigned char *)new;

	pr_emerg("Jump label code mismatch at %pS [%px]\n", ipc, ipc);
	pr_emerg("Found:    %6ph\n", ipc);
	pr_emerg("Expected: %6ph\n", ipe);
	pr_emerg("New:      %6ph\n", ipn);
	panic("Corrupted kernel text");
}

static void jump_label_transform(struct jump_entry *entry,
				 enum jump_label_type type)
{
	void *code = (void *)jump_entry_code(entry);
	struct insn old, new;

	if (type == JUMP_LABEL_JMP) {
		jump_label_make_nop(entry, &old);
		jump_label_make_branch(entry, &new);
	} else {
		jump_label_make_branch(entry, &old);
		jump_label_make_nop(entry, &new);
	}
	if (memcmp(code, &old, sizeof(old)))
		jump_label_bug(entry, &old, &new);
	s390_kernel_write(code, &new, sizeof(new));
}

void arch_jump_label_transform(struct jump_entry *entry,
			       enum jump_label_type type)
{
	jump_label_transform(entry, type);
	text_poke_sync();
}

bool arch_jump_label_transform_queue(struct jump_entry *entry,
				     enum jump_label_type type)
{
	jump_label_transform(entry, type);
	return true;
}

void arch_jump_label_transform_apply(void)
{
	text_poke_sync();
}
Commit	Line	Data
	1	// SPDX-License-Identifier: GPL-2.0
	2	/*
	3	* Jump label s390 support
	4	*
	5	* Copyright IBM Corp. 2011
	6	* Author(s): Jan Glauber <jang@linux.vnet.ibm.com>
	7	*/
	8	#include <linux/uaccess.h>
	9	#include <linux/jump_label.h>
	10	#include <linux/module.h>
	11	#include <asm/text-patching.h>
	12	#include <asm/ipl.h>
	13
	14	struct insn {
	15	u16 opcode;
	16	s32 offset;
	17	} __packed;
	18
	19	static void jump_label_make_nop(struct jump_entry entry, struct insn insn)
	20	{
	21	/* brcl 0,offset */
	22	insn->opcode = 0xc004;
	23	insn->offset = (jump_entry_target(entry) - jump_entry_code(entry)) >> 1;
	24	}
	25
	26	static void jump_label_make_branch(struct jump_entry entry, struct insn insn)
	27	{
	28	/* brcl 15,offset */
	29	insn->opcode = 0xc0f4;
	30	insn->offset = (jump_entry_target(entry) - jump_entry_code(entry)) >> 1;
	31	}
	32
	33	static void jump_label_bug(struct jump_entry entry, struct insn expected,
	34	struct insn *new)
	35	{
	36	unsigned char ipc = (unsigned char )jump_entry_code(entry);
	37	unsigned char ipe = (unsigned char )expected;
	38	unsigned char ipn = (unsigned char )new;
	39
	40	pr_emerg("Jump label code mismatch at %pS [%px]\n", ipc, ipc);
	41	pr_emerg("Found: %6ph\n", ipc);
	42	pr_emerg("Expected: %6ph\n", ipe);
	43	pr_emerg("New: %6ph\n", ipn);
	44	panic("Corrupted kernel text");
	45	}
	46
	47	static void jump_label_transform(struct jump_entry *entry,
	48	enum jump_label_type type)
	49	{
	50	void code = (void )jump_entry_code(entry);
	51	struct insn old, new;
	52
	53	if (type == JUMP_LABEL_JMP) {
	54	jump_label_make_nop(entry, &old);
	55	jump_label_make_branch(entry, &new);
	56	} else {
	57	jump_label_make_branch(entry, &old);
	58	jump_label_make_nop(entry, &new);
	59	}
	60	if (memcmp(code, &old, sizeof(old)))
	61	jump_label_bug(entry, &old, &new);
	62	s390_kernel_write(code, &new, sizeof(new));
	63	}
	64
	65	void arch_jump_label_transform(struct jump_entry *entry,
	66	enum jump_label_type type)
	67	{
	68	jump_label_transform(entry, type);
	69	text_poke_sync();
	70	}
	71
	72	bool arch_jump_label_transform_queue(struct jump_entry *entry,
	73	enum jump_label_type type)
	74	{
	75	jump_label_transform(entry, type);
	76	return true;
	77	}
	78
	79	void arch_jump_label_transform_apply(void)
	80	{
	81	text_poke_sync();
	82	}