1/* SPDX-License-Identifier: GPL-2.0-or-later */ 2#include <linux/objtool.h> 3#include <asm/asm-offsets.h> 4#include <asm/code-patching-asm.h> 5#include <asm/mmu.h> 6#include <asm/ppc_asm.h> 7#include <asm/kup.h> 8#include <asm/thread_info.h> 9 10.section ".text","ax",@progbits 11 12#ifdef CONFIG_PPC_BOOK3S_64 13/* 14 * Cancel all explict user streams as they will have no use after context 15 * switch and will stop the HW from creating streams itself 16 */ 17#define STOP_STREAMS \ 18 DCBT_BOOK3S_STOP_ALL_STREAM_IDS(r6) 19 20#define FLUSH_COUNT_CACHE \ 211: nop; \ 22 patch_site 1b, patch__call_flush_branch_caches1; \ 231: nop; \ 24 patch_site 1b, patch__call_flush_branch_caches2; \ 251: nop; \ 26 patch_site 1b, patch__call_flush_branch_caches3 27 28.macro nops number 29 .rept \number 30 nop 31 .endr 32.endm 33 34.balign 32 35.global flush_branch_caches 36flush_branch_caches: 37 /* Save LR into r9 */ 38 mflr r9 39 40 // Flush the link stack 41 .rept 64 42 ANNOTATE_INTRA_FUNCTION_CALL 43 bl .+4 44 .endr 45 b 1f 46 nops 6 47 48 .balign 32 49 /* Restore LR */ 501: mtlr r9 51 52 // If we're just flushing the link stack, return here 533: nop 54 patch_site 3b patch__flush_link_stack_return 55 56 li r9,0x7fff 57 mtctr r9 58 59 PPC_BCCTR_FLUSH 60 612: nop 62 patch_site 2b patch__flush_count_cache_return 63 64 nops 3 65 66 .rept 278 67 .balign 32 68 PPC_BCCTR_FLUSH 69 nops 7 70 .endr 71 72 blr 73 74#ifdef CONFIG_PPC_64S_HASH_MMU 75.balign 32 76/* 77 * New stack pointer in r8, old stack pointer in r1, must not clobber r3 78 */ 79pin_stack_slb: 80BEGIN_FTR_SECTION 81 clrrdi r6,r8,28 /* get its ESID */ 82 clrrdi r9,r1,28 /* get current sp ESID */ 83FTR_SECTION_ELSE 84 clrrdi r6,r8,40 /* get its 1T ESID */ 85 clrrdi r9,r1,40 /* get current sp 1T ESID */ 86ALT_MMU_FTR_SECTION_END_IFCLR(MMU_FTR_1T_SEGMENT) 87 clrldi. r0,r6,2 /* is new ESID c00000000? */ 88 cmpd cr1,r6,r9 /* or is new ESID the same as current ESID? */ 89 cror eq,4*cr1+eq,eq 90 beq 2f /* if yes, don't slbie it */ 91 92 /* Bolt in the new stack SLB entry */ 93 ld r7,KSP_VSID(r4) /* Get new stack's VSID */ 94 oris r0,r6,(SLB_ESID_V)@h 95 ori r0,r0,(SLB_NUM_BOLTED-1)@l 96BEGIN_FTR_SECTION 97 li r9,MMU_SEGSIZE_1T /* insert B field */ 98 oris r6,r6,(MMU_SEGSIZE_1T << SLBIE_SSIZE_SHIFT)@h 99 rldimi r7,r9,SLB_VSID_SSIZE_SHIFT,0 100END_MMU_FTR_SECTION_IFSET(MMU_FTR_1T_SEGMENT) 101 102 /* Update the last bolted SLB. No write barriers are needed 103 * here, provided we only update the current CPU's SLB shadow 104 * buffer. 105 */ 106 ld r9,PACA_SLBSHADOWPTR(r13) 107 li r12,0 108 std r12,SLBSHADOW_STACKESID(r9) /* Clear ESID */ 109 li r12,SLBSHADOW_STACKVSID 110 STDX_BE r7,r12,r9 /* Save VSID */ 111 li r12,SLBSHADOW_STACKESID 112 STDX_BE r0,r12,r9 /* Save ESID */ 113 114 /* No need to check for MMU_FTR_NO_SLBIE_B here, since when 115 * we have 1TB segments, the only CPUs known to have the errata 116 * only support less than 1TB of system memory and we'll never 117 * actually hit this code path. 118 */ 119 120 isync 121 slbie r6 122BEGIN_FTR_SECTION 123 slbie r6 /* Workaround POWER5 < DD2.1 issue */ 124END_FTR_SECTION_IFCLR(CPU_FTR_ARCH_207S) 125 slbmte r7,r0 126 isync 1272: blr 128 .size pin_stack_slb,.-pin_stack_slb 129#endif /* CONFIG_PPC_64S_HASH_MMU */ 130 131#else 132#define STOP_STREAMS 133#define FLUSH_COUNT_CACHE 134#endif /* CONFIG_PPC_BOOK3S_64 */ 135 136/* 137 * do_switch_32/64 have the same calling convention as _switch, i.e., r3,r4 138 * are prev and next thread_struct *, and returns prev task_struct * in r3. 139 140 * This switches the stack, current, and does other task switch housekeeping. 141 */ 142.macro do_switch_32 143 tophys(r0,r4) 144 mtspr SPRN_SPRG_THREAD,r0 /* Update current THREAD phys addr */ 145 lwz r1,KSP(r4) /* Load new stack pointer */ 146 147 /* save the old current 'last' for return value */ 148 mr r3,r2 149 addi r2,r4,-THREAD /* Update current */ 150.endm 151 152.macro do_switch_64 153 ld r8,KSP(r4) /* Load new stack pointer */ 154 155 kuap_check_amr r9, r10 156 157 FLUSH_COUNT_CACHE /* Clobbers r9, ctr */ 158 159 STOP_STREAMS /* Clobbers r6 */ 160 161 addi r3,r3,-THREAD /* old thread -> task_struct for return value */ 162 addi r6,r4,-THREAD /* new thread -> task_struct */ 163 std r6,PACACURRENT(r13) /* Set new task_struct to 'current' */ 164#if defined(CONFIG_STACKPROTECTOR) 165 ld r6, TASK_CANARY(r6) 166 std r6, PACA_CANARY(r13) 167#endif 168 /* Set new PACAKSAVE */ 169 clrrdi r7,r8,THREAD_SHIFT /* base of new stack */ 170 addi r7,r7,THREAD_SIZE-SWITCH_FRAME_SIZE 171 std r7,PACAKSAVE(r13) 172 173#ifdef CONFIG_PPC_64S_HASH_MMU 174BEGIN_MMU_FTR_SECTION 175 bl pin_stack_slb 176END_MMU_FTR_SECTION_IFCLR(MMU_FTR_TYPE_RADIX) 177#endif 178 /* 179 * PMU interrupts in radix may come in here. They will use r1, not 180 * PACAKSAVE, so this stack switch will not cause a problem. They 181 * will store to the process stack, which may then be migrated to 182 * another CPU. However the rq lock release on this CPU paired with 183 * the rq lock acquire on the new CPU before the stack becomes 184 * active on the new CPU, will order those stores. 185 */ 186 mr r1,r8 /* start using new stack pointer */ 187.endm 188 189/* 190 * This routine switches between two different tasks. The process 191 * state of one is saved on its kernel stack. Then the state 192 * of the other is restored from its kernel stack. The memory 193 * management hardware is updated to the second process's state. 194 * Finally, we can return to the second process. 195 * On entry, r3 points to the THREAD for the current task, r4 196 * points to the THREAD for the new task. 197 * 198 * This routine is always called with interrupts disabled. 199 * 200 * Note: there are two ways to get to the "going out" portion 201 * of this code; either by coming in via the entry (_switch) 202 * or via "fork" which must set up an environment equivalent 203 * to the "_switch" path. If you change this , you'll have to 204 * change the fork code also. 205 * 206 * The code which creates the new task context is in 'copy_thread' 207 * in arch/ppc/kernel/process.c 208 * 209 * Note: this uses SWITCH_FRAME_SIZE rather than USER_INT_FRAME_SIZE 210 * because we don't need to leave the redzone ABI gap at the top of 211 * the kernel stack. 212 */ 213_GLOBAL(_switch) 214 PPC_CREATE_STACK_FRAME(SWITCH_FRAME_SIZE) 215 PPC_STL r1,KSP(r3) /* Set old stack pointer */ 216 SAVE_NVGPRS(r1) /* volatiles are caller-saved -- Cort */ 217 PPC_STL r0,_NIP(r1) /* Return to switch caller */ 218 mfcr r0 219 stw r0,_CCR(r1) 220 221 /* 222 * On SMP kernels, care must be taken because a task may be 223 * scheduled off CPUx and on to CPUy. Memory ordering must be 224 * considered. 225 * 226 * Cacheable stores on CPUx will be visible when the task is 227 * scheduled on CPUy by virtue of the core scheduler barriers 228 * (see "Notes on Program-Order guarantees on SMP systems." in 229 * kernel/sched/core.c). 230 * 231 * Uncacheable stores in the case of involuntary preemption must 232 * be taken care of. The smp_mb__after_spinlock() in __schedule() 233 * is implemented as hwsync on powerpc, which orders MMIO too. So 234 * long as there is an hwsync in the context switch path, it will 235 * be executed on the source CPU after the task has performed 236 * all MMIO ops on that CPU, and on the destination CPU before the 237 * task performs any MMIO ops there. 238 */ 239 240 /* 241 * The kernel context switch path must contain a spin_lock, 242 * which contains larx/stcx, which will clear any reservation 243 * of the task being switched. 244 */ 245 246#ifdef CONFIG_PPC32 247 do_switch_32 248#else 249 do_switch_64 250#endif 251 252 lwz r0,_CCR(r1) 253 mtcrf 0xFF,r0 254 REST_NVGPRS(r1) /* volatiles are destroyed -- Cort */ 255 PPC_LL r0,_NIP(r1) /* Return to _switch caller in new task */ 256 mtlr r0 257 addi r1,r1,SWITCH_FRAME_SIZE 258 blr 259
