// SPDX-License-Identifier: GPL-2.0

#define _GNU_SOURCE
#include <err.h>
#include <errno.h>
#include <setjmp.h>
#include <stdio.h>
#include <string.h>
#include <stdbool.h>
#include <unistd.h>
#include <x86intrin.h>

#include <sys/auxv.h>
#include <sys/mman.h>
#include <sys/shm.h>
#include <sys/syscall.h>
#include <sys/wait.h>

#include "helpers.h"
#include "xstate.h"

#ifndef __x86_64__
# error This test is 64-bit only
#endif

/* err() exits and will not return */
#define fatal_error(msg, ...)   err(1, "[FAIL]\t" msg, ##__VA_ARGS__)

#define XFEATURE_MASK_XTILECFG  (1 << XFEATURE_XTILECFG)
#define XFEATURE_MASK_XTILEDATA (1 << XFEATURE_XTILEDATA)
#define XFEATURE_MASK_XTILE     (XFEATURE_MASK_XTILECFG | XFEATURE_MASK_XTILEDATA)

struct xstate_info xtiledata;

/* The helpers for managing XSAVE buffer and tile states: */

struct xsave_buffer *stashed_xsave;

static void init_stashed_xsave(void)
{
        stashed_xsave = alloc_xbuf();
        if (!stashed_xsave)
                fatal_error("failed to allocate stashed_xsave\n");
        clear_xstate_header(stashed_xsave);
}

static void free_stashed_xsave(void)
{
        free(stashed_xsave);
}

/* Work around printf() being unsafe in signals: */
#define SIGNAL_BUF_LEN 1000
char signal_message_buffer[SIGNAL_BUF_LEN];
void sig_print(char *msg)
{
        int left = SIGNAL_BUF_LEN - strlen(signal_message_buffer) - 1;

        strncat(signal_message_buffer, msg, left);
}

static volatile bool noperm_signaled;
static int noperm_errs;
/*
 * Signal handler for when AMX is used but
 * permission has not been obtained.
 */
static void handle_noperm(int sig, siginfo_t *si, void *ctx_void)
{
        ucontext_t *ctx = (ucontext_t *)ctx_void;
        void *xbuf = ctx->uc_mcontext.fpregs;
        struct _fpx_sw_bytes *sw_bytes;
        uint64_t features;

        /* Reset the signal message buffer: */
        signal_message_buffer[0] = '\0';
        sig_print("\tAt SIGILL handler,\n");

        if (si->si_code != ILL_ILLOPC) {
                noperm_errs++;
                sig_print("[FAIL]\tInvalid signal code.\n");
        } else {
                sig_print("[OK]\tValid signal code (ILL_ILLOPC).\n");
        }

        sw_bytes = get_fpx_sw_bytes(xbuf);
        /*
         * Without permission, the signal XSAVE buffer should not
         * have room for AMX register state (aka. xtiledata).
         * Check that the size does not overlap with where xtiledata
         * will reside.
         *
         * This also implies that no state components *PAST*
         * XTILEDATA (features >=19) can be present in the buffer.
         */
        if (sw_bytes->xstate_size <= xtiledata.xbuf_offset) {
                sig_print("[OK]\tValid xstate size\n");
        } else {
                noperm_errs++;
                sig_print("[FAIL]\tInvalid xstate size\n");
        }

        features = get_fpx_sw_bytes_features(xbuf);
        /*
         * Without permission, the XTILEDATA feature
         * bit should not be set.
         */
        if ((features & XFEATURE_MASK_XTILEDATA) == 0) {
                sig_print("[OK]\tValid xstate mask\n");
        } else {
                noperm_errs++;
                sig_print("[FAIL]\tInvalid xstate mask\n");
        }

        noperm_signaled = true;
        ctx->uc_mcontext.gregs[REG_RIP] += 3; /* Skip the faulting XRSTOR */
}

/* Return true if XRSTOR is successful; otherwise, false. */
static inline bool xrstor_safe(struct xsave_buffer *xbuf, uint64_t mask)
{
        noperm_signaled = false;
        xrstor(xbuf, mask);

        /* Print any messages produced by the signal code: */
        printf("%s", signal_message_buffer);
        /*
         * Reset the buffer to make sure any future printing
         * only outputs new messages:
         */
        signal_message_buffer[0] = '\0';

        if (noperm_errs)
                fatal_error("saw %d errors in noperm signal handler\n", noperm_errs);

        return !noperm_signaled;
}

/*
 * Use XRSTOR to populate the XTILEDATA registers with
 * random data.
 *
 * Return true if successful; otherwise, false.
 */
static inline bool load_rand_tiledata(struct xsave_buffer *xbuf)
{
        clear_xstate_header(xbuf);
        set_xstatebv(xbuf, XFEATURE_MASK_XTILEDATA);
        set_rand_data(&xtiledata, xbuf);
        return xrstor_safe(xbuf, XFEATURE_MASK_XTILEDATA);
}

enum expected_result { FAIL_EXPECTED, SUCCESS_EXPECTED };

/* arch_prctl() and sigaltstack() test */

#define ARCH_GET_XCOMP_SUPP     0x1021
#define ARCH_GET_XCOMP_PERM     0x1022
#define ARCH_REQ_XCOMP_PERM     0x1023

static void req_xtiledata_perm(void)
{
        syscall(SYS_arch_prctl, ARCH_REQ_XCOMP_PERM, XFEATURE_XTILEDATA);
}

static void validate_req_xcomp_perm(enum expected_result exp)
{
        unsigned long bitmask, expected_bitmask;
        long rc;

        rc = syscall(SYS_arch_prctl, ARCH_GET_XCOMP_PERM, &bitmask);
        if (rc) {
                fatal_error("prctl(ARCH_GET_XCOMP_PERM) error: %ld", rc);
        } else if (!(bitmask & XFEATURE_MASK_XTILECFG)) {
                fatal_error("ARCH_GET_XCOMP_PERM returns XFEATURE_XTILECFG off.");
        }

        rc = syscall(SYS_arch_prctl, ARCH_REQ_XCOMP_PERM, XFEATURE_XTILEDATA);
        if (exp == FAIL_EXPECTED) {
                if (rc) {
                        printf("[OK]\tARCH_REQ_XCOMP_PERM saw expected failure..\n");
                        return;
                }

                fatal_error("ARCH_REQ_XCOMP_PERM saw unexpected success.\n");
        } else if (rc) {
                fatal_error("ARCH_REQ_XCOMP_PERM saw unexpected failure.\n");
        }

        expected_bitmask = bitmask | XFEATURE_MASK_XTILEDATA;

        rc = syscall(SYS_arch_prctl, ARCH_GET_XCOMP_PERM, &bitmask);
        if (rc) {
                fatal_error("prctl(ARCH_GET_XCOMP_PERM) error: %ld", rc);
        } else if (bitmask != expected_bitmask) {
                fatal_error("ARCH_REQ_XCOMP_PERM set a wrong bitmask: %lx, expected: %lx.\n",
                            bitmask, expected_bitmask);
        } else {
                printf("\tARCH_REQ_XCOMP_PERM is successful.\n");
        }
}

static void validate_xcomp_perm(enum expected_result exp)
{
        bool load_success = load_rand_tiledata(stashed_xsave);

        if (exp == FAIL_EXPECTED) {
                if (load_success) {
                        noperm_errs++;
                        printf("[FAIL]\tLoad tiledata succeeded.\n");
                } else {
                        printf("[OK]\tLoad tiledata failed.\n");
                }
        } else if (exp == SUCCESS_EXPECTED) {
                if (load_success) {
                        printf("[OK]\tLoad tiledata succeeded.\n");
                } else {
                        noperm_errs++;
                        printf("[FAIL]\tLoad tiledata failed.\n");
                }
        }
}

#ifndef AT_MINSIGSTKSZ
#  define AT_MINSIGSTKSZ        51
#endif

static void *alloc_altstack(unsigned int size)
{
        void *altstack;

        altstack = mmap(NULL, size, PROT_READ | PROT_WRITE,
                        MAP_PRIVATE | MAP_ANONYMOUS | MAP_STACK, -1, 0);

        if (altstack == MAP_FAILED)
                fatal_error("mmap() for altstack");

        return altstack;
}

static void setup_altstack(void *addr, unsigned long size, enum expected_result exp)
{
        stack_t ss;
        int rc;

        memset(&ss, 0, sizeof(ss));
        ss.ss_size = size;
        ss.ss_sp = addr;

        rc = sigaltstack(&ss, NULL);

        if (exp == FAIL_EXPECTED) {
                if (rc) {
                        printf("[OK]\tsigaltstack() failed.\n");
                } else {
                        fatal_error("sigaltstack() succeeded unexpectedly.\n");
                }
        } else if (rc) {
                fatal_error("sigaltstack()");
        }
}

static void test_dynamic_sigaltstack(void)
{
        unsigned int small_size, enough_size;
        unsigned long minsigstksz;
        void *altstack;

        minsigstksz = getauxval(AT_MINSIGSTKSZ);
        printf("\tAT_MINSIGSTKSZ = %lu\n", minsigstksz);
        /*
         * getauxval() itself can return 0 for failure or
         * success.  But, in this case, AT_MINSIGSTKSZ
         * will always return a >=0 value if implemented.
         * Just check for 0.
         */
        if (minsigstksz == 0) {
                printf("no support for AT_MINSIGSTKSZ, skipping sigaltstack tests\n");
                return;
        }

        enough_size = minsigstksz * 2;

        altstack = alloc_altstack(enough_size);
        printf("\tAllocate memory for altstack (%u bytes).\n", enough_size);

        /*
         * Try setup_altstack() with a size which can not fit
         * XTILEDATA.  ARCH_REQ_XCOMP_PERM should fail.
         */
        small_size = minsigstksz - xtiledata.size;
        printf("\tAfter sigaltstack() with small size (%u bytes).\n", small_size);
        setup_altstack(altstack, small_size, SUCCESS_EXPECTED);
        validate_req_xcomp_perm(FAIL_EXPECTED);

        /*
         * Try setup_altstack() with a size derived from
         * AT_MINSIGSTKSZ.  It should be more than large enough
         * and thus ARCH_REQ_XCOMP_PERM should succeed.
         */
        printf("\tAfter sigaltstack() with enough size (%u bytes).\n", enough_size);
        setup_altstack(altstack, enough_size, SUCCESS_EXPECTED);
        validate_req_xcomp_perm(SUCCESS_EXPECTED);

        /*
         * Try to coerce setup_altstack() to again accept a
         * too-small altstack.  This ensures that big-enough
         * sigaltstacks can not shrink to a too-small value
         * once XTILEDATA permission is established.
         */
        printf("\tThen, sigaltstack() with small size (%u bytes).\n", small_size);
        setup_altstack(altstack, small_size, FAIL_EXPECTED);
}

static void test_dynamic_state(void)
{
        pid_t parent, child, grandchild;

        parent = fork();
        if (parent < 0) {
                /* fork() failed */
                fatal_error("fork");
        } else if (parent > 0) {
                int status;
                /* fork() succeeded.  Now in the parent. */

                wait(&status);
                if (!WIFEXITED(status) || WEXITSTATUS(status))
                        fatal_error("arch_prctl test parent exit");
                return;
        }
        /* fork() succeeded.  Now in the child . */

        printf("[RUN]\tCheck ARCH_REQ_XCOMP_PERM around process fork() and sigaltack() test.\n");

        printf("\tFork a child.\n");
        child = fork();
        if (child < 0) {
                fatal_error("fork");
        } else if (child > 0) {
                int status;

                wait(&status);
                if (!WIFEXITED(status) || WEXITSTATUS(status))
                        fatal_error("arch_prctl test child exit");
                _exit(0);
        }

        /*
         * The permission request should fail without an
         * XTILEDATA-compatible signal stack
         */
        printf("\tTest XCOMP_PERM at child.\n");
        validate_xcomp_perm(FAIL_EXPECTED);

        /*
         * Set up an XTILEDATA-compatible signal stack and
         * also obtain permission to populate XTILEDATA.
         */
        printf("\tTest dynamic sigaltstack at child:\n");
        test_dynamic_sigaltstack();

        /* Ensure that XTILEDATA can be populated. */
        printf("\tTest XCOMP_PERM again at child.\n");
        validate_xcomp_perm(SUCCESS_EXPECTED);

        printf("\tFork a grandchild.\n");
        grandchild = fork();
        if (grandchild < 0) {
                /* fork() failed */
                fatal_error("fork");
        } else if (!grandchild) {
                /* fork() succeeded.  Now in the (grand)child. */
                printf("\tTest XCOMP_PERM at grandchild.\n");

                /*
                 * Ensure that the grandchild inherited
                 * permission and a compatible sigaltstack:
                 */
                validate_xcomp_perm(SUCCESS_EXPECTED);
        } else {
                int status;
                /* fork() succeeded.  Now in the parent. */

                wait(&status);
                if (!WIFEXITED(status) || WEXITSTATUS(status))
                        fatal_error("fork test grandchild");
        }

        _exit(0);
}

static inline int __compare_tiledata_state(struct xsave_buffer *xbuf1, struct xsave_buffer *xbuf2)
{
        return memcmp(&xbuf1->bytes[xtiledata.xbuf_offset],
                      &xbuf2->bytes[xtiledata.xbuf_offset],
                      xtiledata.size);
}

/*
 * Save current register state and compare it to @xbuf1.'
 *
 * Returns false if @xbuf1 matches the registers.
 * Returns true  if @xbuf1 differs from the registers.
 */
static inline bool __validate_tiledata_regs(struct xsave_buffer *xbuf1)
{
        struct xsave_buffer *xbuf2;
        int ret;

        xbuf2 = alloc_xbuf();
        if (!xbuf2)
                fatal_error("failed to allocate XSAVE buffer\n");

        xsave(xbuf2, XFEATURE_MASK_XTILEDATA);
        ret = __compare_tiledata_state(xbuf1, xbuf2);

        free(xbuf2);

        if (ret == 0)
                return false;
        return true;
}

static inline void validate_tiledata_regs_changed(struct xsave_buffer *xbuf)
{
        int ret = __validate_tiledata_regs(xbuf);

        if (ret == 0)
                fatal_error("TILEDATA registers did not change");
}

/* tiledata inheritance test */

static void test_fork(void)
{
        pid_t child, grandchild;

        child = fork();
        if (child < 0) {
                /* fork() failed */
                fatal_error("fork");
        } else if (child > 0) {
                /* fork() succeeded.  Now in the parent. */
                int status;

                wait(&status);
                if (!WIFEXITED(status) || WEXITSTATUS(status))
                        fatal_error("fork test child");
                return;
        }
        /* fork() succeeded.  Now in the child. */
        printf("[RUN]\tCheck tile data inheritance.\n\tBefore fork(), load tiledata\n");

        load_rand_tiledata(stashed_xsave);

        grandchild = fork();
        if (grandchild < 0) {
                /* fork() failed */
                fatal_error("fork");
        } else if (grandchild > 0) {
                /* fork() succeeded.  Still in the first child. */
                int status;

                wait(&status);
                if (!WIFEXITED(status) || WEXITSTATUS(status))
                        fatal_error("fork test grand child");
                _exit(0);
        }
        /* fork() succeeded.  Now in the (grand)child. */

        /*
         * TILEDATA registers are not preserved across fork().
         * Ensure that their value has changed:
         */
        validate_tiledata_regs_changed(stashed_xsave);

        _exit(0);
}

int main(void)
{
        unsigned long features;
        long rc;

        rc = syscall(SYS_arch_prctl, ARCH_GET_XCOMP_SUPP, &features);
        if (rc || (features & XFEATURE_MASK_XTILE) != XFEATURE_MASK_XTILE) {
                ksft_print_msg("no AMX support\n");
                return KSFT_SKIP;
        }

        xtiledata = get_xstate_info(XFEATURE_XTILEDATA);
        if (!xtiledata.size || !xtiledata.xbuf_offset) {
                fatal_error("xstate cpuid: invalid tile data size/offset: %d/%d",
                            xtiledata.size, xtiledata.xbuf_offset);
        }

        init_stashed_xsave();
        sethandler(SIGILL, handle_noperm, 0);

        test_dynamic_state();

        /* Request permission for the following tests */
        req_xtiledata_perm();

        test_fork();

        /*
         * Perform generic xstate tests for context switching, ptrace,
         * and signal.
         */
        test_xstate(XFEATURE_XTILEDATA);

        clearhandler(SIGILL);
        free_stashed_xsave();

        return 0;
}