[linux-2.6-block.git] / arch / s390 / kernel / alternative.c

// SPDX-License-Identifier: GPL-2.0

#ifndef pr_fmt
#define pr_fmt(fmt)	"alt: " fmt
#endif

#include <linux/uaccess.h>
#include <linux/printk.h>
#include <asm/nospec-branch.h>
#include <asm/abs_lowcore.h>
#include <asm/alternative.h>
#include <asm/facility.h>
#include <asm/sections.h>
#include <asm/machine.h>

#ifndef a_debug
#define a_debug		pr_debug
#endif

#ifndef __kernel_va
#define __kernel_va(x)	(void *)(x)
#endif

unsigned long __bootdata_preserved(machine_features[1]);

struct alt_debug {
	unsigned long facilities[MAX_FACILITY_BIT / BITS_PER_LONG];
	unsigned long mfeatures[MAX_MFEATURE_BIT / BITS_PER_LONG];
	int spec;
};

static struct alt_debug __bootdata_preserved(alt_debug);

static void alternative_dump(u8 *old, u8 *new, unsigned int len, unsigned int type, unsigned int data)
{
	char oinsn[33], ninsn[33];
	unsigned long kptr;
	unsigned int pos;

	for (pos = 0; pos < len && 2 * pos < sizeof(oinsn) - 3; pos++)
		hex_byte_pack(&oinsn[2 * pos], old[pos]);
	oinsn[2 * pos] = 0;
	for (pos = 0; pos < len && 2 * pos < sizeof(ninsn) - 3; pos++)
		hex_byte_pack(&ninsn[2 * pos], new[pos]);
	ninsn[2 * pos] = 0;
	kptr = (unsigned long)__kernel_va(old);
	a_debug("[%d/%3d] %016lx: %s -> %s\n", type, data, kptr, oinsn, ninsn);
}

void __apply_alternatives(struct alt_instr *start, struct alt_instr *end, unsigned int ctx)
{
	struct alt_debug *d;
	struct alt_instr *a;
	bool debug, replace;
	u8 *old, *new;

	/*
	 * The scan order should be from start to end. A later scanned
	 * alternative code can overwrite previously scanned alternative code.
	 */
	d = &alt_debug;
	for (a = start; a < end; a++) {
		if (!(a->ctx & ctx))
			continue;
		switch (a->type) {
		case ALT_TYPE_FACILITY:
			replace = test_facility(a->data);
			debug = __test_facility(a->data, d->facilities);
			break;
		case ALT_TYPE_FEATURE:
			replace = test_machine_feature(a->data);
			debug = __test_machine_feature(a->data, d->mfeatures);
			break;
		case ALT_TYPE_SPEC:
			replace = nobp_enabled();
			debug = d->spec;
			break;
		default:
			replace = false;
			debug = false;
		}
		if (!replace)
			continue;
		old = (u8 *)&a->instr_offset + a->instr_offset;
		new = (u8 *)&a->repl_offset + a->repl_offset;
		if (debug)
			alternative_dump(old, new, a->instrlen, a->type, a->data);
		s390_kernel_write(old, new, a->instrlen);
	}
}
Commit	Line	Data
9fa1db4c	1	// SPDX-License-Identifier: GPL-2.0
b3e0c5f7	2
f0f6db9f HC	3	#ifndef pr_fmt
	4	#define pr_fmt(fmt) "alt: " fmt
	5	#endif
	6
b3e0c5f7	7	#include <linux/uaccess.h>
f0f6db9f	8	#include <linux/printk.h>
47837a5c	9	#include <asm/nospec-branch.h>
5ade5be4	10	#include <asm/abs_lowcore.h>
686140a1 VG	11	#include <asm/alternative.h>
686140a1 VG	12	#include <asm/facility.h>
b7e81efc HC	13	#include <asm/sections.h>
	14	#include <asm/machine.h>
	15
f0f6db9f HC	16	#ifndef a_debug
	17	#define a_debug pr_debug
	18	#endif
	19
	20	#ifndef __kernel_va
	21	#define __kernel_va(x) (void *)(x)
	22	#endif
	23
b7e81efc	24	unsigned long __bootdata_preserved(machine_features[1]);
686140a1	25
f0f6db9f HC	26	struct alt_debug {
	27	unsigned long facilities[MAX_FACILITY_BIT / BITS_PER_LONG];
	28	unsigned long mfeatures[MAX_MFEATURE_BIT / BITS_PER_LONG];
	29	int spec;
	30	};
	31
	32	static struct alt_debug __bootdata_preserved(alt_debug);
	33
	34	static void alternative_dump(u8 old, u8 new, unsigned int len, unsigned int type, unsigned int data)
	35	{
	36	char oinsn[33], ninsn[33];
	37	unsigned long kptr;
	38	unsigned int pos;
	39
	40	for (pos = 0; pos < len && 2 * pos < sizeof(oinsn) - 3; pos++)
	41	hex_byte_pack(&oinsn[2 * pos], old[pos]);
	42	oinsn[2 * pos] = 0;
	43	for (pos = 0; pos < len && 2 * pos < sizeof(ninsn) - 3; pos++)
	44	hex_byte_pack(&ninsn[2 * pos], new[pos]);
	45	ninsn[2 * pos] = 0;
	46	kptr = (unsigned long)__kernel_va(old);
	47	a_debug("[%d/%3d] %016lx: %s -> %s\n", type, data, kptr, oinsn, ninsn);
	48	}
	49
b3e0c5f7	50	void __apply_alternatives(struct alt_instr start, struct alt_instr end, unsigned int ctx)
686140a1	51	{
f0f6db9f	52	struct alt_debug *d;
b3e0c5f7	53	struct alt_instr *a;
f0f6db9f HC	54	bool debug, replace;
f0f6db9f HC	55	u8 old, new;
686140a1 VG	56
	57	/*
	58	* The scan order should be from start to end. A later scanned
	59	* alternative code can overwrite previously scanned alternative code.
	60	*/
f0f6db9f	61	d = &alt_debug;
686140a1	62	for (a = start; a < end; a++) {
b3e0c5f7 HC	63	if (!(a->ctx & ctx))
	64	continue;
	65	switch (a->type) {
	66	case ALT_TYPE_FACILITY:
beb8cee0	67	replace = test_facility(a->data);
f0f6db9f	68	debug = __test_facility(a->data, d->facilities);
b3e0c5f7	69	break;
b7e81efc HC	70	case ALT_TYPE_FEATURE:
b7e81efc HC	71	replace = test_machine_feature(a->data);
f0f6db9f	72	debug = __test_machine_feature(a->data, d->mfeatures);
b7e81efc	73	break;
47837a5c HC	74	case ALT_TYPE_SPEC:
47837a5c HC	75	replace = nobp_enabled();
f0f6db9f	76	debug = d->spec;
47837a5c	77	break;
b3e0c5f7 HC	78	default:
b3e0c5f7 HC	79	replace = false;
f0f6db9f	80	debug = false;
b3e0c5f7 HC	81	}
	82	if (!replace)
	83	continue;
f0f6db9f HC	84	old = (u8 *)&a->instr_offset + a->instr_offset;
	85	new = (u8 *)&a->repl_offset + a->repl_offset;
	86	if (debug)
	87	alternative_dump(old, new, a->instrlen, a->type, a->data);
	88	s390_kernel_write(old, new, a->instrlen);
686140a1 VG	89	}
686140a1 VG	90	}