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

#include <linux/compiler.h>
#include <asm/thread_info.h>

#ifdef __ASSEMBLY__
#include <asm/asm-offsets.h>
        .macro switch_tls_none, base, tp, tpuser, tmp1, tmp2
        .endm

        .macro switch_tls_v6k, base, tp, tpuser, tmp1, tmp2
        mrc     p15, 0, \tmp2, c13, c0, 2       @ get the user r/w register
        @ TLS register update is deferred until return to user space
        mcr     p15, 0, \tpuser, c13, c0, 2     @ set the user r/w register
        str     \tmp2, [\base, #TI_TP_VALUE + 4] @ save it
        .endm

        .macro switch_tls_v6, base, tp, tpuser, tmp1, tmp2
#ifdef CONFIG_SMP
ALT_SMP(nop)
ALT_UP_B(.L0_\@)
        .subsection 1
#endif
.L0_\@:
        ldr_va  \tmp1, elf_hwcap
        mov     \tmp2, #0xffff0fff
        tst     \tmp1, #HWCAP_TLS               @ hardware TLS available?
        streq   \tp, [\tmp2, #-15]              @ set TLS value at 0xffff0ff0
        beq     .L2_\@
        mcr     p15, 0, \tp, c13, c0, 3         @ yes, set TLS register
#ifdef CONFIG_SMP
        b       .L1_\@
        .previous
#endif
.L1_\@: switch_tls_v6k \base, \tp, \tpuser, \tmp1, \tmp2
.L2_\@:
        .endm

        .macro switch_tls_software, base, tp, tpuser, tmp1, tmp2
        mov     \tmp1, #0xffff0fff
        str     \tp, [\tmp1, #-15]              @ set TLS value at 0xffff0ff0
        .endm
#else
#include <asm/smp_plat.h>
#endif

#ifdef CONFIG_TLS_REG_EMUL
#define tls_emu         1
#define has_tls_reg             1
#define defer_tls_reg_update    0
#define switch_tls      switch_tls_none
#elif defined(CONFIG_CPU_V6)
#define tls_emu         0
#define has_tls_reg             (elf_hwcap & HWCAP_TLS)
#define defer_tls_reg_update    is_smp()
#define switch_tls      switch_tls_v6
#elif defined(CONFIG_CPU_32v6K)
#define tls_emu         0
#define has_tls_reg             1
#define defer_tls_reg_update    1
#define switch_tls      switch_tls_v6k
#else
#define tls_emu         0
#define has_tls_reg             0
#define defer_tls_reg_update    0
#define switch_tls      switch_tls_software
#endif

#ifndef __ASSEMBLY__

static inline void set_tls(unsigned long val)
{
        struct thread_info *thread;

        thread = current_thread_info();

        thread->tp_value[0] = val;

        /*
         * This code runs with preemption enabled and therefore must
         * be reentrant with respect to switch_tls.
         *
         * We need to ensure ordering between the shadow state and the
         * hardware state, so that we don't corrupt the hardware state
         * with a stale shadow state during context switch.
         *
         * If we're preempted here, switch_tls will load TPIDRURO from
         * thread_info upon resuming execution and the following mcr
         * is merely redundant.
         */
        barrier();

        if (!tls_emu) {
                if (has_tls_reg && !defer_tls_reg_update) {
                        asm("mcr p15, 0, %0, c13, c0, 3"
                            : : "r" (val));
                } else if (!has_tls_reg) {
#ifdef CONFIG_KUSER_HELPERS
                        /*
                         * User space must never try to access this
                         * directly.  Expect your app to break
                         * eventually if you do so.  The user helper
                         * at 0xffff0fe0 must be used instead.  (see
                         * entry-armv.S for details)
                         */
                        *((unsigned int *)0xffff0ff0) = val;
#endif
                }

        }
}

static inline unsigned long get_tpuser(void)
{
        unsigned long reg = 0;

        if (has_tls_reg && !tls_emu)
                __asm__("mrc p15, 0, %0, c13, c0, 2" : "=r" (reg));

        return reg;
}

static inline void set_tpuser(unsigned long val)
{
        /* Since TPIDRURW is fully context-switched (unlike TPIDRURO),
         * we need not update thread_info.
         */
        if (has_tls_reg && !tls_emu) {
                asm("mcr p15, 0, %0, c13, c0, 2"
                    : : "r" (val));
        }
}

static inline void flush_tls(void)
{
        set_tls(0);
        set_tpuser(0);
}

#endif
#endif  /* __ASMARM_TLS_H */