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// 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);
}
}
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