mirror of https://github.com/torvalds/linux.git
91 lines
2.3 KiB
C
91 lines
2.3 KiB
C
// SPDX-License-Identifier: GPL-2.0
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#ifndef pr_fmt
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#define pr_fmt(fmt) "alt: " fmt
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#endif
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#include <linux/uaccess.h>
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#include <linux/printk.h>
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#include <asm/nospec-branch.h>
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#include <asm/abs_lowcore.h>
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#include <asm/alternative.h>
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#include <asm/facility.h>
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#include <asm/sections.h>
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#include <asm/machine.h>
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#ifndef a_debug
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#define a_debug pr_debug
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#endif
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#ifndef __kernel_va
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#define __kernel_va(x) (void *)(x)
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#endif
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unsigned long __bootdata_preserved(machine_features[1]);
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struct alt_debug {
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unsigned long facilities[MAX_FACILITY_BIT / BITS_PER_LONG];
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unsigned long mfeatures[MAX_MFEATURE_BIT / BITS_PER_LONG];
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int spec;
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};
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static struct alt_debug __bootdata_preserved(alt_debug);
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static void alternative_dump(u8 *old, u8 *new, unsigned int len, unsigned int type, unsigned int data)
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{
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char oinsn[33], ninsn[33];
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unsigned long kptr;
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unsigned int pos;
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for (pos = 0; pos < len && 2 * pos < sizeof(oinsn) - 3; pos++)
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hex_byte_pack(&oinsn[2 * pos], old[pos]);
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oinsn[2 * pos] = 0;
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for (pos = 0; pos < len && 2 * pos < sizeof(ninsn) - 3; pos++)
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hex_byte_pack(&ninsn[2 * pos], new[pos]);
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ninsn[2 * pos] = 0;
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kptr = (unsigned long)__kernel_va(old);
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a_debug("[%d/%3d] %016lx: %s -> %s\n", type, data, kptr, oinsn, ninsn);
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}
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void __apply_alternatives(struct alt_instr *start, struct alt_instr *end, unsigned int ctx)
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{
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struct alt_debug *d;
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struct alt_instr *a;
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bool debug, replace;
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u8 *old, *new;
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/*
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* The scan order should be from start to end. A later scanned
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* alternative code can overwrite previously scanned alternative code.
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*/
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d = &alt_debug;
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for (a = start; a < end; a++) {
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if (!(a->ctx & ctx))
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continue;
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switch (a->type) {
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case ALT_TYPE_FACILITY:
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replace = test_facility(a->data);
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debug = __test_facility(a->data, d->facilities);
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break;
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case ALT_TYPE_FEATURE:
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replace = test_machine_feature(a->data);
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debug = __test_machine_feature(a->data, d->mfeatures);
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break;
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case ALT_TYPE_SPEC:
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replace = nobp_enabled();
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debug = d->spec;
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break;
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default:
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replace = false;
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debug = false;
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}
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if (!replace)
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continue;
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old = (u8 *)&a->instr_offset + a->instr_offset;
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new = (u8 *)&a->repl_offset + a->repl_offset;
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if (debug)
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alternative_dump(old, new, a->instrlen, a->type, a->data);
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s390_kernel_write(old, new, a->instrlen);
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}
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}
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