/* SPDX-License-Identifier: GPL-2.0 */
#include <linux/errno.h>
#include <linux/linkage.h>
#include <asm/asm-offsets.h>
#include <asm/assembler.h>
#include <asm/smp.h>

        .text
/*
 * Implementation of MPIDR_EL1 hash algorithm through shifting
 * and OR'ing.
 *
 * @dst: register containing hash result
 * @rs0: register containing affinity level 0 bit shift
 * @rs1: register containing affinity level 1 bit shift
 * @rs2: register containing affinity level 2 bit shift
 * @rs3: register containing affinity level 3 bit shift
 * @mpidr: register containing MPIDR_EL1 value
 * @mask: register containing MPIDR mask
 *
 * Pseudo C-code:
 *
 *u32 dst;
 *
 *compute_mpidr_hash(u32 rs0, u32 rs1, u32 rs2, u32 rs3, u64 mpidr, u64 mask) {
 *      u32 aff0, aff1, aff2, aff3;
 *      u64 mpidr_masked = mpidr & mask;
 *      aff0 = mpidr_masked & 0xff;
 *      aff1 = mpidr_masked & 0xff00;
 *      aff2 = mpidr_masked & 0xff0000;
 *      aff3 = mpidr_masked & 0xff00000000;
 *      dst = (aff0 >> rs0 | aff1 >> rs1 | aff2 >> rs2 | aff3 >> rs3);
 *}
 * Input registers: rs0, rs1, rs2, rs3, mpidr, mask
 * Output register: dst
 * Note: input and output registers must be disjoint register sets
         (eg: a macro instance with mpidr = x1 and dst = x1 is invalid)
 */
        .macro compute_mpidr_hash dst, rs0, rs1, rs2, rs3, mpidr, mask
        and     \mpidr, \mpidr, \mask           // mask out MPIDR bits
        and     \dst, \mpidr, #0xff             // mask=aff0
        lsr     \dst ,\dst, \rs0                // dst=aff0>>rs0
        and     \mask, \mpidr, #0xff00          // mask = aff1
        lsr     \mask ,\mask, \rs1
        orr     \dst, \dst, \mask               // dst|=(aff1>>rs1)
        and     \mask, \mpidr, #0xff0000        // mask = aff2
        lsr     \mask ,\mask, \rs2
        orr     \dst, \dst, \mask               // dst|=(aff2>>rs2)
        and     \mask, \mpidr, #0xff00000000    // mask = aff3
        lsr     \mask ,\mask, \rs3
        orr     \dst, \dst, \mask               // dst|=(aff3>>rs3)
        .endm
/*
 * Save CPU state in the provided sleep_stack_data area, and publish its
 * location for cpu_resume()'s use in sleep_save_stash.
 *
 * cpu_resume() will restore this saved state, and return. Because the
 * link-register is saved and restored, it will appear to return from this
 * function. So that the caller can tell the suspend/resume paths apart,
 * __cpu_suspend_enter() will always return a non-zero value, whereas the
 * path through cpu_resume() will return 0.
 *
 *  x0 = struct sleep_stack_data area
 */
SYM_FUNC_START(__cpu_suspend_enter)
        stp     x29, lr, [x0, #SLEEP_STACK_DATA_CALLEE_REGS]
        stp     x19, x20, [x0,#SLEEP_STACK_DATA_CALLEE_REGS+16]
        stp     x21, x22, [x0,#SLEEP_STACK_DATA_CALLEE_REGS+32]
        stp     x23, x24, [x0,#SLEEP_STACK_DATA_CALLEE_REGS+48]
        stp     x25, x26, [x0,#SLEEP_STACK_DATA_CALLEE_REGS+64]
        stp     x27, x28, [x0,#SLEEP_STACK_DATA_CALLEE_REGS+80]

        /* save the sp in cpu_suspend_ctx */
        mov     x2, sp
        str     x2, [x0, #SLEEP_STACK_DATA_SYSTEM_REGS + CPU_CTX_SP]

        /* find the mpidr_hash */
        ldr_l   x1, sleep_save_stash
        mrs     x7, mpidr_el1
        adr_l   x9, mpidr_hash
        ldr     x10, [x9, #MPIDR_HASH_MASK]
        /*
         * Following code relies on the struct mpidr_hash
         * members size.
         */
        ldp     w3, w4, [x9, #MPIDR_HASH_SHIFTS]
        ldp     w5, w6, [x9, #(MPIDR_HASH_SHIFTS + 8)]
        compute_mpidr_hash x8, x3, x4, x5, x6, x7, x10
        add     x1, x1, x8, lsl #3

        str     x0, [x1]
        add     x0, x0, #SLEEP_STACK_DATA_SYSTEM_REGS
        stp     x29, lr, [sp, #-16]!
        bl      cpu_do_suspend
        ldp     x29, lr, [sp], #16
        mov     x0, #1
        ret
SYM_FUNC_END(__cpu_suspend_enter)

        .pushsection ".idmap.text", "a"
SYM_CODE_START(cpu_resume)
        mov     x0, xzr
        bl      init_kernel_el
        mov     x19, x0                 // preserve boot mode
        bl      __cpu_setup
        /* enable the MMU early - so we can access sleep_save_stash by va */
        adrp    x1, swapper_pg_dir
        adrp    x2, idmap_pg_dir
        bl      __enable_mmu
        ldr     x8, =_cpu_resume
        br      x8
SYM_CODE_END(cpu_resume)
        .ltorg
        .popsection

SYM_FUNC_START(_cpu_resume)
        mov     x0, x19
        bl      finalise_el2

        mrs     x1, mpidr_el1
        adr_l   x8, mpidr_hash          // x8 = struct mpidr_hash virt address

        /* retrieve mpidr_hash members to compute the hash */
        ldr     x2, [x8, #MPIDR_HASH_MASK]
        ldp     w3, w4, [x8, #MPIDR_HASH_SHIFTS]
        ldp     w5, w6, [x8, #(MPIDR_HASH_SHIFTS + 8)]
        compute_mpidr_hash x7, x3, x4, x5, x6, x1, x2

        /* x7 contains hash index, let's use it to grab context pointer */
        ldr_l   x0, sleep_save_stash
        ldr     x0, [x0, x7, lsl #3]
        add     x29, x0, #SLEEP_STACK_DATA_CALLEE_REGS
        add     x0, x0, #SLEEP_STACK_DATA_SYSTEM_REGS
        /* load sp from context */
        ldr     x2, [x0, #CPU_CTX_SP]
        mov     sp, x2
        /*
         * cpu_do_resume expects x0 to contain context address pointer
         */
        bl      cpu_do_resume

#if defined(CONFIG_KASAN) && defined(CONFIG_KASAN_STACK)
        mov     x0, sp
        bl      kasan_unpoison_task_stack_below
#endif

        ldp     x19, x20, [x29, #16]
        ldp     x21, x22, [x29, #32]
        ldp     x23, x24, [x29, #48]
        ldp     x25, x26, [x29, #64]
        ldp     x27, x28, [x29, #80]
        ldp     x29, lr, [x29]
        mov     x0, #0
        ret
SYM_FUNC_END(_cpu_resume)