1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Alternative live-patching for parisc.
4 * Copyright (C) 2018 Helge Deller <deller@gmx.de>
5 *
6 */
7
8 #include <asm/processor.h>
9 #include <asm/sections.h>
10 #include <asm/alternative.h>
11 #include <asm/cacheflush.h>
12
13 #include <linux/module.h>
14
15 static int no_alternatives;
16 static int __init setup_no_alternatives(char *str)
17 {
18 no_alternatives = 1;
19 return 1;
20 }
21 __setup("no-alternatives", setup_no_alternatives);
22
23 void __init_or_module apply_alternatives(struct alt_instr *start,
24 struct alt_instr *end, const char *module_name)
25 {
26 struct alt_instr *entry;
27 int index = 0, applied = 0;
28 int num_cpus = num_present_cpus();
29 u16 cond_check;
30
31 cond_check = ALT_COND_ALWAYS |
32 ((num_cpus == 1) ? ALT_COND_NO_SMP : 0) |
33 ((cache_info.dc_size == 0) ? ALT_COND_NO_DCACHE : 0) |
34 ((cache_info.ic_size == 0) ? ALT_COND_NO_ICACHE : 0) |
35 (running_on_qemu ? ALT_COND_RUN_ON_QEMU : 0) |
36 ((split_tlb == 0) ? ALT_COND_NO_SPLIT_TLB : 0) |
37 /*
38 * If the PDC_MODEL capabilities has Non-coherent IO-PDIR bit
39 * set (bit #61, big endian), we have to flush and sync every
40 * time IO-PDIR is changed in Ike/Astro.
41 */
42 (((boot_cpu_data.cpu_type > pcxw_) &&
43 ((boot_cpu_data.pdc.capabilities & PDC_MODEL_IOPDIR_FDC) == 0))
44 ? ALT_COND_NO_IOC_FDC : 0);
45
46 for (entry = start; entry < end; entry++, index++) {
47
48 u32 *from, replacement;
49 u16 cond;
50 s16 len;
51
52 from = (u32 *)((ulong)&entry->orig_offset + entry->orig_offset);
53 len = entry->len;
54 cond = entry->cond;
55 replacement = entry->replacement;
56
57 WARN_ON(!cond);
58
59 if ((cond & ALT_COND_ALWAYS) == 0 && no_alternatives)
60 continue;
61
62 pr_debug("Check %d: Cond 0x%x, Replace %02d instructions @ 0x%px with 0x%08x\n",
63 index, cond, len, from, replacement);
64
65 /* Bounce out if none of the conditions are true. */
66 if ((cond & cond_check) == 0)
67 continue;
68
69 /* Want to replace pdtlb by a pdtlb,l instruction? */
70 if (replacement == INSN_PxTLB) {
71 replacement = *from;
72 if (boot_cpu_data.cpu_type >= pcxu) /* >= pa2.0 ? */
73 replacement |= (1 << 10); /* set el bit */
74 }
75
76 /*
77 * Replace instruction with NOPs?
78 * For long distance insert a branch instruction instead.
79 */
80 if (replacement == INSN_NOP && len > 1)
81 replacement = 0xe8000002 + (len-2)*8; /* "b,n .+8" */
82
83 pr_debug("ALTERNATIVE %3d: Cond %2x, Replace %2d instructions to 0x%08x @ 0x%px (%pS)\n",
84 index, cond, len, replacement, from, from);
85
86 if (len < 0) {
87 /* Replace multiple instruction by new code */
88 u32 *source;
89 len = -len;
90 source = (u32 *)((ulong)&entry->replacement + entry->replacement);
91 memcpy(from, source, 4 * len);
92 } else {
93 /* Replace by one instruction */
94 *from = replacement;
95 }
96 applied++;
97 }
98
99 pr_info("%s%salternatives: applied %d out of %d patches\n",
100 module_name ? : "", module_name ? " " : "",
101 applied, index);
102 }
103
104
105 void __init apply_alternatives_all(void)
106 {
107 set_kernel_text_rw(1);
108
109 apply_alternatives((struct alt_instr *) &__alt_instructions,
110 (struct alt_instr *) &__alt_instructions_end, NULL);
111
112 if (cache_info.dc_size == 0 && cache_info.ic_size == 0) {
113 pr_info("alternatives: optimizing cache-flushes.\n");
114 static_branch_disable(&parisc_has_cache);
115 }
116 if (cache_info.dc_size == 0)
117 static_branch_disable(&parisc_has_dcache);
118 if (cache_info.ic_size == 0)
119 static_branch_disable(&parisc_has_icache);
120
121 set_kernel_text_rw(0);
122 }
123
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