LXR linux/arch/sparc/include/asm/switch_to

   1/* SPDX-License-Identifier: GPL-2.0 */
   2#ifndef __SPARC_SWITCH_TO_H
   3#define __SPARC_SWITCH_TO_H
   4
   5#include <asm/smp.h>
   6
   7extern struct thread_info *current_set[NR_CPUS];
   8
   9/*
  10 * Flush windows so that the VM switch which follows
  11 * would not pull the stack from under us.
  12 *
  13 * SWITCH_ENTER and SWITCH_DO_LAZY_FPU do not work yet (e.g. SMP does not work)
  14 * XXX WTF is the above comment? Found in late teen 2.4.x.
  15 */
  16#ifdef CONFIG_SMP
  17#define SWITCH_ENTER(prv) \
  18        do {                    \
  19        if (test_tsk_thread_flag(prv, TIF_USEDFPU)) { \
  20                put_psr(get_psr() | PSR_EF); \
  21                fpsave(&(prv)->thread.float_regs[0], &(prv)->thread.fsr, \
  22                       &(prv)->thread.fpqueue[0], &(prv)->thread.fpqdepth); \
  23                clear_tsk_thread_flag(prv, TIF_USEDFPU); \
  24                (prv)->thread.kregs->psr &= ~PSR_EF; \
  25        } \
  26        } while(0)
  27
  28#define SWITCH_DO_LAZY_FPU(next)        /* */
  29#else
  30#define SWITCH_ENTER(prv)               /* */
  31#define SWITCH_DO_LAZY_FPU(nxt) \
  32        do {                    \
  33        if (last_task_used_math != (nxt))               \
  34                (nxt)->thread.kregs->psr&=~PSR_EF;      \
  35        } while(0)
  36#endif
  37
  38#define prepare_arch_switch(next) do { \
  39        __asm__ __volatile__( \
  40        ".globl\tflush_patch_switch\nflush_patch_switch:\n\t" \
  41        "save %sp, -0x40, %sp; save %sp, -0x40, %sp; save %sp, -0x40, %sp\n\t" \
  42        "save %sp, -0x40, %sp; save %sp, -0x40, %sp; save %sp, -0x40, %sp\n\t" \
  43        "save %sp, -0x40, %sp\n\t" \
  44        "restore; restore; restore; restore; restore; restore; restore"); \
  45} while(0)
  46
  47        /* Much care has gone into this code, do not touch it.
  48         *
  49         * We need to loadup regs l0/l1 for the newly forked child
  50         * case because the trap return path relies on those registers
  51         * holding certain values, gcc is told that they are clobbered.
  52         * Gcc needs registers for 3 values in and 1 value out, so we
  53         * clobber every non-fixed-usage register besides l2/l3/o4/o5.  -DaveM
  54         *
  55         * Hey Dave, that do not touch sign is too much of an incentive
  56         * - Anton & Pete
  57         */
  58#define switch_to(prev, next, last) do {                                                \
  59        SWITCH_ENTER(prev);                                                             \
  60        SWITCH_DO_LAZY_FPU(next);                                                       \
  61        cpumask_set_cpu(smp_processor_id(), mm_cpumask(next->active_mm));               \
  62        __asm__ __volatile__(                                                           \
  63        "sethi  %%hi(here - 0x8), %%o7\n\t"                                             \
  64        "mov    %%g6, %%g3\n\t"                                                         \
  65        "or     %%o7, %%lo(here - 0x8), %%o7\n\t"                                       \
  66        "rd     %%psr, %%g4\n\t"                                                        \
  67        "std    %%sp, [%%g6 + %4]\n\t"                                                  \
  68        "rd     %%wim, %%g5\n\t"                                                        \
  69        "wr     %%g4, 0x20, %%psr\n\t"                                                  \
  70        "nop\n\t"                                                                       \
  71        "std    %%g4, [%%g6 + %3]\n\t"                                                  \
  72        "ldd    [%2 + %3], %%g4\n\t"                                                    \
  73        "mov    %2, %%g6\n\t"                                                           \
  74        ".globl patchme_store_new_current\n"                                            \
  75"patchme_store_new_current:\n\t"                                                        \
  76        "st     %2, [%1]\n\t"                                                           \
  77        "wr     %%g4, 0x20, %%psr\n\t"                                                  \
  78        "nop\n\t"                                                                       \
  79        "nop\n\t"                                                                       \
  80        "nop\n\t"       /* LEON needs all 3 nops: load to %sp depends on CWP. */                \
  81        "ldd    [%%g6 + %4], %%sp\n\t"                                                  \
  82        "wr     %%g5, 0x0, %%wim\n\t"                                                   \
  83        "ldd    [%%sp + 0x00], %%l0\n\t"                                                \
  84        "ldd    [%%sp + 0x38], %%i6\n\t"                                                \
  85        "wr     %%g4, 0x0, %%psr\n\t"                                                   \
  86        "nop\n\t"                                                                       \
  87        "nop\n\t"                                                                       \
  88        "jmpl   %%o7 + 0x8, %%g0\n\t"                                                   \
  89        " ld    [%%g3 + %5], %0\n\t"                                                    \
  90        "here:\n"                                                                       \
  91        : "=&r" (last)                                                                  \
  92        : "r" (&(current_set[hard_smp_processor_id()])),        \
  93          "r" (task_thread_info(next)),                         \
  94          "i" (TI_KPSR),                                        \
  95          "i" (TI_KSP),                                         \
  96          "i" (TI_TASK)                                         \
  97        :       "g1", "g2", "g3", "g4", "g5",       "g7",       \
  98          "l0", "l1",       "l3", "l4", "l5", "l6", "l7",       \
  99          "i0", "i1", "i2", "i3", "i4", "i5",                   \
 100          "o0", "o1", "o2", "o3",                   "o7");      \
 101        } while(0)
 102
 103void fpsave(unsigned long *fpregs, unsigned long *fsr,
 104            void *fpqueue, unsigned long *fpqdepth);
 105void synchronize_user_stack(void);
 106
 107#endif /* __SPARC_SWITCH_TO_H */
 108