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// SPDX-License-Identifier: GPL-2.0-only
/*
* Copyright 2019, Gustavo Romero, Michael Neuling, IBM Corp.
*
* This test will spawn two processes. Both will be attached to the same
* CPU (CPU 0). The child will be in a loop writing to FP register f31 and
* VMX/VEC/Altivec register vr31 a known value, called poison, calling
* sched_yield syscall after to allow the parent to switch on the CPU.
* Parent will set f31 and vr31 to 1 and in a loop will check if f31 and
* vr31 remain 1 as expected until a given timeout (2m). If the issue is
* present child's poison will leak into parent's f31 or vr31 registers,
* otherwise, poison will never leak into parent's f31 and vr31 registers.
*/
#define _GNU_SOURCE
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <inttypes.h>
#include <sched.h>
#include <sys/types.h>
#include <signal.h>
#include <inttypes.h>
#include "tm.h"
int tm_poison_test(void)
{
int cpu, pid;
cpu_set_t cpuset;
uint64_t poison = 0xdeadbeefc0dec0fe;
uint64_t unknown = 0;
bool fail_fp = false;
bool fail_vr = false;
SKIP_IF(!have_htm());
cpu = pick_online_cpu();
FAIL_IF(cpu < 0);
// Attach both Child and Parent to the same CPU
CPU_ZERO(&cpuset);
CPU_SET(cpu, &cpuset);
FAIL_IF(sched_setaffinity(0, sizeof(cpuset), &cpuset) != 0);
pid = fork();
if (!pid) {
/**
* child
*/
while (1) {
sched_yield();
asm (
"mtvsrd 31, %[poison];" // f31 = poison
"mtvsrd 63, %[poison];" // vr31 = poison
: : [poison] "r" (poison) : );
}
}
/**
* parent
*/
asm (
/*
* Set r3, r4, and f31 to known value 1 before entering
* in transaction. They won't be written after that.
*/
" li 3, 0x1 ;"
" li 4, 0x1 ;"
" mtvsrd 31, 4 ;"
/*
* The Time Base (TB) is a 64-bit counter register that is
* independent of the CPU clock and which is incremented
* at a frequency of 512000000 Hz, so every 1.953125ns.
* So it's necessary 120s/0.000000001953125s = 61440000000
* increments to get a 2 minutes timeout. Below we set that
* value in r5 and then use r6 to track initial TB value,
* updating TB values in r7 at every iteration and comparing it
* to r6. When r7 (current) - r6 (initial) > 61440000000 we bail
* out since for sure we spent already 2 minutes in the loop.
* SPR 268 is the TB register.
*/
" lis 5, 14 ;"
" ori 5, 5, 19996 ;"
" sldi 5, 5, 16 ;" // r5 = 61440000000
" mfspr 6, 268 ;" // r6 (TB initial)
"1: mfspr 7, 268 ;" // r7 (TB current)
" subf 7, 6, 7 ;" // r7 - r6 > 61440000000 ?
" cmpd 7, 5 ;"
" bgt 3f ;" // yes, exit
/*
* Main loop to check f31
*/
" tbegin. ;" // no, try again
" beq 1b ;" // restart if no timeout
" mfvsrd 3, 31 ;" // read f31
" cmpd 3, 4 ;" // f31 == 1 ?
" bne 2f ;" // broken :-(
" tabort. 3 ;" // try another transaction
"2: tend. ;" // commit transaction
"3: mr %[unknown], 3 ;" // record r3
: [unknown] "=r" (unknown)
:
: "cr0", "r3", "r4", "r5", "r6", "r7", "vs31"
);
/*
* On leak 'unknown' will contain 'poison' value from child,
* otherwise (no leak) 'unknown' will contain the same value
* as r3 before entering in transactional mode, i.e. 0x1.
*/
fail_fp = unknown != 0x1;
if (fail_fp)
printf("Unknown value %#"PRIx64" leaked into f31!\n", unknown);
else
printf("Good, no poison or leaked value into FP registers\n");
asm (
/*
* Set r3, r4, and vr31 to known value 1 before entering
* in transaction. They won't be written after that.
*/
" li 3, 0x1 ;"
" li 4, 0x1 ;"
" mtvsrd 63, 4 ;"
" lis 5, 14 ;"
" ori 5, 5, 19996 ;"
" sldi 5, 5, 16 ;" // r5 = 61440000000
" mfspr 6, 268 ;" // r6 (TB initial)
"1: mfspr 7, 268 ;" // r7 (TB current)
" subf 7, 6, 7 ;" // r7 - r6 > 61440000000 ?
" cmpd 7, 5 ;"
" bgt 3f ;" // yes, exit
/*
* Main loop to check vr31
*/
" tbegin. ;" // no, try again
" beq 1b ;" // restart if no timeout
" mfvsrd 3, 63 ;" // read vr31
" cmpd 3, 4 ;" // vr31 == 1 ?
" bne 2f ;" // broken :-(
" tabort. 3 ;" // try another transaction
"2: tend. ;" // commit transaction
"3: mr %[unknown], 3 ;" // record r3
: [unknown] "=r" (unknown)
:
: "cr0", "r3", "r4", "r5", "r6", "r7", "vs63"
);
/*
* On leak 'unknown' will contain 'poison' value from child,
* otherwise (no leak) 'unknown' will contain the same value
* as r3 before entering in transactional mode, i.e. 0x1.
*/
fail_vr = unknown != 0x1;
if (fail_vr)
printf("Unknown value %#"PRIx64" leaked into vr31!\n", unknown);
else
printf("Good, no poison or leaked value into VEC registers\n");
kill(pid, SIGKILL);
return (fail_fp | fail_vr);
}
int main(int argc, char *argv[])
{
/* Test completes in about 4m */
test_harness_set_timeout(250);
return test_harness(tm_poison_test, "tm_poison_test");
}
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