| 1 | |
| 2 |
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| 3 | #ifndef pr_fmt
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| 4 | #define pr_fmt(fmt) "alt: " fmt
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| 5 | #endif
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| 6 |
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| 7 | #include <linux/hex.h>
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| 8 | #include <linux/uaccess.h>
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| 9 | #include <linux/printk.h>
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| 10 | #include <asm/nospec-branch.h>
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| 11 | #include <asm/abs_lowcore.h>
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| 12 | #include <asm/alternative.h>
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| 13 | #include <asm/facility.h>
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| 14 | #include <asm/sections.h>
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| 15 | #include <asm/machine.h>
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| 16 |
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| 17 | #ifndef a_debug
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| 18 | #define a_debug pr_debug
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| 19 | #endif
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| 20 |
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| 21 | #ifndef __kernel_va
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| 22 | #define __kernel_va(x) (void *)(x)
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| 23 | #endif
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| 24 |
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| 25 | unsigned long __bootdata_preserved(machine_features[1]);
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| 26 |
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| 27 | struct alt_debug {
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| 28 | unsigned long facilities[MAX_FACILITY_BIT / BITS_PER_LONG];
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| 29 | unsigned long mfeatures[MAX_MFEATURE_BIT / BITS_PER_LONG];
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| 30 | int spec;
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| 31 | };
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| 32 |
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| 33 | static struct alt_debug __bootdata_preserved(alt_debug);
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| 34 |
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| 35 | static void alternative_dump(u8 *old, u8 *new, unsigned int len, unsigned int type, unsigned int data)
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| 36 | {
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| 37 | char oinsn[33], ninsn[33];
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| 38 | unsigned long kptr;
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| 39 | unsigned int pos;
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| 40 |
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| 41 | for (pos = 0; pos < len && 2 * pos < sizeof(oinsn) - 3; pos++)
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| 42 | hex_byte_pack(&oinsn[2 * pos], old[pos]);
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| 43 | oinsn[2 * pos] = 0;
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| 44 | for (pos = 0; pos < len && 2 * pos < sizeof(ninsn) - 3; pos++)
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| 45 | hex_byte_pack(&ninsn[2 * pos], new[pos]);
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| 46 | ninsn[2 * pos] = 0;
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| 47 | kptr = (unsigned long)__kernel_va(old);
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| 48 | a_debug("[%d/%3d] %016lx: %s -> %s\n", type, data, kptr, oinsn, ninsn);
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| 49 | }
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| 50 |
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| 51 | void __apply_alternatives(struct alt_instr *start, struct alt_instr *end, unsigned int ctx)
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| 52 | {
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| 53 | struct alt_debug *d;
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| 54 | struct alt_instr *a;
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| 55 | bool debug, replace;
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| 56 | u8 *old, *new;
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| 57 |
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| 58 | |
| 59 | * The scan order should be from start to end. A later scanned
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| 60 | * alternative code can overwrite previously scanned alternative code.
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| 61 |
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| 62 | d = &alt_debug;
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| 63 | for (a = start; a < end; a++) {
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| 64 | if (!(a->ctx & ctx))
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| 65 | continue;
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| 66 | switch (a->type) {
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| 67 | case ALT_TYPE_FACILITY:
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| 68 | replace = test_facility(a->data);
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| 69 | debug = __test_facility(a->data, d->facilities);
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| 70 | break;
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| 71 | case ALT_TYPE_FEATURE:
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| 72 | replace = test_machine_feature(a->data);
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| 73 | debug = __test_machine_feature(a->data, d->mfeatures);
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| 74 | break;
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| 75 | case ALT_TYPE_SPEC:
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| 76 | replace = nobp_enabled();
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| 77 | debug = d->spec;
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| 78 | break;
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| 79 | default:
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| 80 | replace = false;
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| 81 | debug = false;
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| 82 | }
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| 83 | if (!replace)
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| 84 | continue;
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| 85 | old = (u8 *)&a->instr_offset + a->instr_offset;
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| 86 | new = (u8 *)&a->repl_offset + a->repl_offset;
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| 87 | if (debug)
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| 88 | alternative_dump(old, new, a->instrlen, a->type, a->data);
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| 89 | s390_kernel_write(old, new, a->instrlen);
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| 90 | }
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| 91 | }
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