/* SPDX-License-Identifier: GPL-2.0 */
#ifndef __SPARC_SWITCH_TO_H
#define __SPARC_SWITCH_TO_H

#include <asm/smp.h>

extern struct thread_info *current_set[NR_CPUS];

/*
 * Flush windows so that the VM switch which follows
 * would not pull the stack from under us.
 *
 * SWITCH_ENTER and SWITCH_DO_LAZY_FPU do not work yet (e.g. SMP does not work)
 * XXX WTF is the above comment? Found in late teen 2.4.x.
 */
#ifdef CONFIG_SMP
#define SWITCH_ENTER(prv) \
        do {                    \
        if (test_tsk_thread_flag(prv, TIF_USEDFPU)) { \
                put_psr(get_psr() | PSR_EF); \
                fpsave(&(prv)->thread.float_regs[0], &(prv)->thread.fsr, \
                       &(prv)->thread.fpqueue[0], &(prv)->thread.fpqdepth); \
                clear_tsk_thread_flag(prv, TIF_USEDFPU); \
                (prv)->thread.kregs->psr &= ~PSR_EF; \
        } \
        } while(0)

#define SWITCH_DO_LAZY_FPU(next)        /* */
#else
#define SWITCH_ENTER(prv)               /* */
#define SWITCH_DO_LAZY_FPU(nxt) \
        do {                    \
        if (last_task_used_math != (nxt))               \
                (nxt)->thread.kregs->psr&=~PSR_EF;      \
        } while(0)
#endif

#define prepare_arch_switch(next) do { \
        __asm__ __volatile__( \
        ".globl\tflush_patch_switch\nflush_patch_switch:\n\t" \
        "save %sp, -0x40, %sp; save %sp, -0x40, %sp; save %sp, -0x40, %sp\n\t" \
        "save %sp, -0x40, %sp; save %sp, -0x40, %sp; save %sp, -0x40, %sp\n\t" \
        "save %sp, -0x40, %sp\n\t" \
        "restore; restore; restore; restore; restore; restore; restore"); \
} while(0)

        /* Much care has gone into this code, do not touch it.
         *
         * We need to loadup regs l0/l1 for the newly forked child
         * case because the trap return path relies on those registers
         * holding certain values, gcc is told that they are clobbered.
         * Gcc needs registers for 3 values in and 1 value out, so we
         * clobber every non-fixed-usage register besides l2/l3/o4/o5.  -DaveM
         *
         * Hey Dave, that do not touch sign is too much of an incentive
         * - Anton & Pete
         */
#define switch_to(prev, next, last) do {                                                \
        SWITCH_ENTER(prev);                                                             \
        SWITCH_DO_LAZY_FPU(next);                                                       \
        cpumask_set_cpu(smp_processor_id(), mm_cpumask(next->active_mm));               \
        __asm__ __volatile__(                                                           \
        "sethi  %%hi(here - 0x8), %%o7\n\t"                                             \
        "mov    %%g6, %%g3\n\t"                                                         \
        "or     %%o7, %%lo(here - 0x8), %%o7\n\t"                                       \
        "rd     %%psr, %%g4\n\t"                                                        \
        "std    %%sp, [%%g6 + %4]\n\t"                                                  \
        "rd     %%wim, %%g5\n\t"                                                        \
        "wr     %%g4, 0x20, %%psr\n\t"                                                  \
        "nop\n\t"                                                                       \
        "std    %%g4, [%%g6 + %3]\n\t"                                                  \
        "ldd    [%2 + %3], %%g4\n\t"                                                    \
        "mov    %2, %%g6\n\t"                                                           \
        ".globl patchme_store_new_current\n"                                            \
"patchme_store_new_current:\n\t"                                                        \
        "st     %2, [%1]\n\t"                                                           \
        "wr     %%g4, 0x20, %%psr\n\t"                                                  \
        "nop\n\t"                                                                       \
        "nop\n\t"                                                                       \
        "nop\n\t"       /* LEON needs all 3 nops: load to %sp depends on CWP. */                \
        "ldd    [%%g6 + %4], %%sp\n\t"                                                  \
        "wr     %%g5, 0x0, %%wim\n\t"                                                   \
        "ldd    [%%sp + 0x00], %%l0\n\t"                                                \
        "ldd    [%%sp + 0x38], %%i6\n\t"                                                \
        "wr     %%g4, 0x0, %%psr\n\t"                                                   \
        "nop\n\t"                                                                       \
        "nop\n\t"                                                                       \
        "jmpl   %%o7 + 0x8, %%g0\n\t"                                                   \
        " ld    [%%g3 + %5], %0\n\t"                                                    \
        "here:\n"                                                                       \
        : "=&r" (last)                                                                  \
        : "r" (&(current_set[hard_smp_processor_id()])),        \
          "r" (task_thread_info(next)),                         \
          "i" (TI_KPSR),                                        \
          "i" (TI_KSP),                                         \
          "i" (TI_TASK)                                         \
        :       "g1", "g2", "g3", "g4", "g5",       "g7",       \
          "l0", "l1",       "l3", "l4", "l5", "l6", "l7",       \
          "i0", "i1", "i2", "i3", "i4", "i5",                   \
          "o0", "o1", "o2", "o3",                   "o7");      \
        } while(0)

void fpsave(unsigned long *fpregs, unsigned long *fsr,
            void *fpqueue, unsigned long *fpqdepth);
void synchronize_user_stack(void);

#endif /* __SPARC_SWITCH_TO_H */