// SPDX-License-Identifier: GPL-2.0-only
// Copyright (C) 2021-2 ARM Limited.
// Original author: Mark Brown <broonie@kernel.org>
//
// Scalable Matrix Extension ZT context switch test
// Repeatedly writes unique test patterns into ZT0
// and reads them back to verify integrity.

#include <asm/unistd.h>
#include "assembler.h"
#include "asm-offsets.h"
#include "sme-inst.h"

.arch_extension sve

#define ZT_SZ   512
#define ZT_B    (ZT_SZ / 8)

// Declare some storage space to shadow ZT register contents and a
// scratch buffer.
.pushsection .text
.data
.align 4
ztref:
        .space  ZT_B
scratch:
        .space  ZT_B
.popsection


// Generate a test pattern for storage in ZT
// x0: pid
// x1: generation

// These values are used to construct a 32-bit pattern that is repeated in the
// scratch buffer as many times as will fit:
// bits 31:24   generation number (increments once per test_loop)
// bits 23: 8   pid
// bits  7: 0   32-bit lane index

function pattern
        mov     w3, wzr
        bfi     w3, w0, #8, #16         // PID
        bfi     w3, w1, #24, #8         // Generation

        ldr     x0, =scratch
        mov     w1, #ZT_B / 4

0:      str     w3, [x0], #4
        add     w3, w3, #1              // Lane
        subs    w1, w1, #1
        b.ne    0b

        ret
endfunction

// Set up test pattern in a ZT horizontal vector
// x0: pid
// x1: generation
function setup_zt
        mov     x4, x30

        bl      pattern                 // Get pattern in scratch buffer
        ldr     x0, =ztref
        ldr     x1, =scratch
        mov     x2, #ZT_B
        bl      memcpy

        ldr     x0, =ztref
        _ldr_zt 0                       // load zt0 from pointer x0

        ret     x4
endfunction

// Trivial memory compare: compare x2 bytes starting at address x0 with
// bytes starting at address x1.
// Returns only if all bytes match; otherwise, the program is aborted.
// Clobbers x0-x5.
function memcmp
        cbz     x2, 2f

        stp     x0, x1, [sp, #-0x20]!
        str     x2, [sp, #0x10]

        mov     x5, #0
0:      ldrb    w3, [x0, x5]
        ldrb    w4, [x1, x5]
        add     x5, x5, #1
        cmp     w3, w4
        b.ne    1f
        subs    x2, x2, #1
        b.ne    0b

1:      ldr     x2, [sp, #0x10]
        ldp     x0, x1, [sp], #0x20
        b.ne    barf

2:      ret
endfunction

// Verify that a ZT vector matches its shadow in memory, else abort
// Clobbers x0-x3
function check_zt
        mov     x3, x30

        ldr     x0, =scratch            // Poison scratch
        mov     x1, #ZT_B
        bl      memfill_ae

        ldr     x0, =scratch
        _str_zt 0

        ldr     x0, =ztref
        ldr     x1, =scratch
        mov     x2, #ZT_B
        mov     x30, x3
        b       memcmp
endfunction

// Modify the live SME register state, signal return will undo our changes
function irritator_handler
        // Increment the irritation signal count (x23):
        ldr     x0, [x2, #ucontext_regs + 8 * 23]
        add     x0, x0, #1
        str     x0, [x2, #ucontext_regs + 8 * 23]

        // This will reset ZT to all bits 0
        smstop
        smstart_za

        ret
endfunction

function tickle_handler
        // Increment the signal count (x23):
        ldr     x0, [x2, #ucontext_regs + 8 * 23]
        add     x0, x0, #1
        str     x0, [x2, #ucontext_regs + 8 * 23]

        ret
endfunction

function terminate_handler
        mov     w21, w0
        mov     x20, x2

        puts    "Terminated by signal "
        mov     w0, w21
        bl      putdec
        puts    ", no error, iterations="
        ldr     x0, [x20, #ucontext_regs + 8 * 22]
        bl      putdec
        puts    ", signals="
        ldr     x0, [x20, #ucontext_regs + 8 * 23]
        bl      putdecn

        mov     x0, #0
        mov     x8, #__NR_exit
        svc     #0
endfunction

// w0: signal number
// x1: sa_action
// w2: sa_flags
// Clobbers x0-x6,x8
function setsignal
        str     x30, [sp, #-((sa_sz + 15) / 16 * 16 + 16)]!

        mov     w4, w0
        mov     x5, x1
        mov     w6, w2

        add     x0, sp, #16
        mov     x1, #sa_sz
        bl      memclr

        mov     w0, w4
        add     x1, sp, #16
        str     w6, [x1, #sa_flags]
        str     x5, [x1, #sa_handler]
        mov     x2, #0
        mov     x3, #sa_mask_sz
        mov     x8, #__NR_rt_sigaction
        svc     #0

        cbz     w0, 1f

        puts    "sigaction failure\n"
        b       .Labort

1:      ldr     x30, [sp], #((sa_sz + 15) / 16 * 16 + 16)
        ret
endfunction

// Main program entry point
.globl _start
function _start
        enable_gcs

        mov     x23, #0         // signal count

        mov     w0, #SIGINT
        adr     x1, terminate_handler
        mov     w2, #SA_SIGINFO
        bl      setsignal

        mov     w0, #SIGTERM
        adr     x1, terminate_handler
        mov     w2, #SA_SIGINFO
        bl      setsignal

        mov     w0, #SIGUSR1
        adr     x1, irritator_handler
        mov     w2, #SA_SIGINFO
        orr     w2, w2, #SA_NODEFER
        bl      setsignal

        mov     w0, #SIGUSR2
        adr     x1, tickle_handler
        mov     w2, #SA_SIGINFO
        orr     w2, w2, #SA_NODEFER
        bl      setsignal

        smstart_za

        // Obtain our PID, to ensure test pattern uniqueness between processes
        mov     x8, #__NR_getpid
        svc     #0
        mov     x20, x0

        puts    "PID:\t"
        mov     x0, x20
        bl      putdecn

        mov     x22, #0         // generation number, increments per iteration
.Ltest_loop:
        mov     x0, x20
        mov     x1, x22
        bl      setup_zt

        mov     x8, #__NR_sched_yield   // Encourage preemption
        svc     #0

        mrs     x0, S3_3_C4_C2_2        // SVCR should have ZA=1,SM=0
        and     x1, x0, #3
        cmp     x1, #2
        b.ne    svcr_barf

        bl      check_zt

        add     x22, x22, #1    // Everything still working
        b       .Ltest_loop

.Labort:
        mov     x0, #0
        mov     x1, #SIGABRT
        mov     x8, #__NR_kill
        svc     #0
endfunction

function barf
// fpsimd.c acitivty log dump hack
//      ldr     w0, =0xdeadc0de
//      mov     w8, #__NR_exit
//      svc     #0
// end hack

        mrs     x13, S3_3_C4_C2_2
        smstop
        mov     x10, x0 // expected data
        mov     x11, x1 // actual data
        mov     x12, x2 // data size

        puts    "Mismatch: PID="
        mov     x0, x20
        bl      putdec
        puts    ", iteration="
        mov     x0, x22
        bl      putdecn
        puts    "\tExpected ["
        mov     x0, x10
        mov     x1, x12
        bl      dumphex
        puts    "]\n\tGot      ["
        mov     x0, x11
        mov     x1, x12
        bl      dumphex
        puts    "]\n"
        puts    "\tSVCR: "
        mov     x0, x13
        bl      putdecn

        mov     x8, #__NR_getpid
        svc     #0
// fpsimd.c acitivty log dump hack
//      ldr     w0, =0xdeadc0de
//      mov     w8, #__NR_exit
//      svc     #0
// ^ end of hack
        mov     x1, #SIGABRT
        mov     x8, #__NR_kill
        svc     #0
//      mov     x8, #__NR_exit
//      mov     x1, #1
//      svc     #0
endfunction

function svcr_barf
        mov     x10, x0

        puts    "Bad SVCR: "
        mov     x0, x10
        bl      putdecn

        mov     x8, #__NR_exit
        mov     x1, #1
        svc     #0
endfunction