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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 | /* SPDX-License-Identifier: GPL-2.0 */ /* * Purgatory setup code * * Copyright IBM Corp. 2018 * * Author(s): Philipp Rudo <prudo@linux.vnet.ibm.com> */ #include <linux/linkage.h> #include <asm/asm-offsets.h> #include <asm/page.h> #include <asm/sigp.h> #include <asm/ptrace.h> /* The purgatory is the code running between two kernels. It's main purpose * is to verify that the next kernel was not corrupted after load and to * start it. * * If the next kernel is a crash kernel there are some peculiarities to * consider: * * First the purgatory is called twice. Once only to verify the * sha digest. So if the crash kernel got corrupted the old kernel can try * to trigger a stand-alone dumper. And once to actually load the crash kernel. * * Second the purgatory also has to swap the crash memory region with its * destination at address 0. As the purgatory is part of crash memory this * requires some finesse. The tactic here is that the purgatory first copies * itself to the end of the destination and then swaps the rest of the * memory running from there. */ #define bufsz purgatory_end-stack .macro MEMCPY dst,src,len lgr %r0,\dst lgr %r1,\len lgr %r2,\src lgr %r3,\len 20: mvcle %r0,%r2,0 jo 20b .endm .macro MEMSWAP dst,src,buf,len 10: larl %r0,purgatory_end larl %r1,stack slgr %r0,%r1 cgr \len,%r0 jh 11f lgr %r4,\len j 12f 11: lgr %r4,%r0 12: MEMCPY \buf,\dst,%r4 MEMCPY \dst,\src,%r4 MEMCPY \src,\buf,%r4 agr \dst,%r4 agr \src,%r4 sgr \len,%r4 cghi \len,0 jh 10b .endm .macro START_NEXT_KERNEL base subcode lg %r4,kernel_entry-\base(%r13) lg %r5,load_psw_mask-\base(%r13) ogr %r4,%r5 stg %r4,0(%r0) xgr %r0,%r0 lghi %r1,\subcode diag %r0,%r1,0x308 .endm .text .align PAGE_SIZE ENTRY(purgatory_start) /* The purgatory might be called after a diag308 so better set * architecture and addressing mode. */ lhi %r1,1 sigp %r1,%r0,SIGP_SET_ARCHITECTURE sam64 larl %r5,gprregs stmg %r6,%r15,0(%r5) basr %r13,0 .base_crash: /* Setup stack */ larl %r15,purgatory_end-STACK_FRAME_OVERHEAD /* If the next kernel is KEXEC_TYPE_CRASH the purgatory is called * directly with a flag passed in %r2 whether the purgatory shall do * checksum verification only (%r2 = 0 -> verification only). * * Check now and preserve over C function call by storing in * %r10 whith * 1 -> checksum verification only * 0 -> load new kernel */ lghi %r10,0 lg %r11,kernel_type-.base_crash(%r13) cghi %r11,1 /* KEXEC_TYPE_CRASH */ jne .do_checksum_verification cghi %r2,0 /* checksum verification only */ jne .do_checksum_verification lghi %r10,1 .do_checksum_verification: brasl %r14,verify_sha256_digest cghi %r10,1 /* checksum verification only */ je .return_old_kernel cghi %r2,0 /* checksum match */ jne .disabled_wait /* If the next kernel is a crash kernel the purgatory has to swap * the mem regions first. */ cghi %r11,1 /* KEXEC_TYPE_CRASH */ je .start_crash_kernel /* start normal kernel */ START_NEXT_KERNEL .base_crash 0 .return_old_kernel: lmg %r6,%r15,gprregs-.base_crash(%r13) br %r14 .disabled_wait: lpswe disabled_wait_psw-.base_crash(%r13) .start_crash_kernel: /* Location of purgatory_start in crash memory */ larl %r0,.base_crash larl %r1,purgatory_start slgr %r0,%r1 lgr %r8,%r13 sgr %r8,%r0 /* Destination for this code i.e. end of memory to be swapped. */ larl %r0,purgatory_end larl %r1,purgatory_start slgr %r0,%r1 lg %r9,crash_size-.base_crash(%r13) sgr %r9,%r0 /* Destination in crash memory, i.e. same as r9 but in crash memory. */ lg %r10,crash_start-.base_crash(%r13) agr %r10,%r9 /* Buffer location (in crash memory) and size. As the purgatory is * behind the point of no return it can re-use the stack as buffer. */ larl %r11,purgatory_end larl %r12,stack slgr %r11,%r12 MEMCPY %r12,%r9,%r11 /* dst -> (crash) buf */ MEMCPY %r9,%r8,%r11 /* self -> dst */ /* Jump to new location. */ lgr %r7,%r9 larl %r0,.jump_to_dst larl %r1,purgatory_start slgr %r0,%r1 agr %r7,%r0 br %r7 .jump_to_dst: basr %r13,0 .base_dst: /* clear buffer */ MEMCPY %r12,%r10,%r11 /* (crash) buf -> (crash) dst */ /* Load new buffer location after jump */ larl %r7,stack lgr %r0,%r7 larl %r1,purgatory_start slgr %r0,%r1 agr %r10,%r0 MEMCPY %r10,%r7,%r11 /* (new) buf -> (crash) buf */ /* Now the code is set up to run from its designated location. Start * swapping the rest of crash memory now. * * The registers will be used as follow: * * %r0-%r4 reserved for macros defined above * %r5-%r6 tmp registers * %r7 pointer to current struct sha region * %r8 index to iterate over all sha regions * %r9 pointer in crash memory * %r10 pointer in old kernel * %r11 total size (still) to be moved * %r12 pointer to buffer */ lgr %r12,%r7 lgr %r11,%r9 lghi %r10,0 lg %r9,crash_start-.base_dst(%r13) lghi %r8,16 /* KEXEC_SEGMENTS_MAX */ larl %r7,purgatory_sha_regions j .loop_first /* Loop over all purgatory_sha_regions. */ .loop_next: aghi %r8,-1 cghi %r8,0 je .loop_out aghi %r7,__KEXEC_SHA_REGION_SIZE .loop_first: lg %r5,__KEXEC_SHA_REGION_START(%r7) cghi %r5,0 je .loop_next /* Copy [end last sha region, start current sha region) */ /* Note: kexec_sha_region->start points in crash memory */ sgr %r5,%r9 MEMCPY %r9,%r10,%r5 agr %r9,%r5 agr %r10,%r5 sgr %r11,%r5 /* Swap sha region */ lg %r6,__KEXEC_SHA_REGION_LEN(%r7) MEMSWAP %r9,%r10,%r12,%r6 sg %r11,__KEXEC_SHA_REGION_LEN(%r7) j .loop_next .loop_out: /* Copy rest of crash memory */ MEMCPY %r9,%r10,%r11 /* start crash kernel */ START_NEXT_KERNEL .base_dst 1 load_psw_mask: .long 0x00080000,0x80000000 .align 8 disabled_wait_psw: .quad 0x0002000180000000 .quad 0x0000000000000000 + .do_checksum_verification gprregs: .rept 10 .quad 0 .endr /* Macro to define a global variable with name and size (in bytes) to be * shared with C code. * * Add the .size and .type attribute to satisfy checks on the Elf_Sym during * purgatory load. */ .macro GLOBAL_VARIABLE name,size \name: .global \name .size \name,\size .type \name,object .skip \size,0 .endm GLOBAL_VARIABLE purgatory_sha256_digest,32 GLOBAL_VARIABLE purgatory_sha_regions,16*__KEXEC_SHA_REGION_SIZE GLOBAL_VARIABLE kernel_entry,8 GLOBAL_VARIABLE kernel_type,8 GLOBAL_VARIABLE crash_start,8 GLOBAL_VARIABLE crash_size,8 .align PAGE_SIZE stack: /* The buffer to move this code must be as big as the code. */ .skip stack-purgatory_start .align PAGE_SIZE purgatory_end: |