cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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tm-signal-context-chk-gpr.c (3304B)

      1// SPDX-License-Identifier: GPL-2.0-or-later
      2/*
      3 * Copyright 2016, Cyril Bur, IBM Corp.
      4 *
      5 * Test the kernel's signal frame code.
      6 *
      7 * The kernel sets up two sets of ucontexts if the signal was to be
      8 * delivered while the thread was in a transaction (referred too as
      9 * first and second contexts).
     10 * Expected behaviour is that the checkpointed state is in the user
     11 * context passed to the signal handler (first context). The speculated
     12 * state can be accessed with the uc_link pointer (second context).
     13 *
     14 * The rationale for this is that if TM unaware code (which linked
     15 * against TM libs) installs a signal handler it will not know of the
     16 * speculative nature of the 'live' registers and may infer the wrong
     17 * thing.
     18 */
     19
     20#include <stdlib.h>
     21#include <stdio.h>
     22#include <signal.h>
     23#include <unistd.h>
     24
     25#include <altivec.h>
     26
     27#include "utils.h"
     28#include "tm.h"
     29
     30#define MAX_ATTEMPT 500000
     31
     32#define NV_GPR_REGS 18 /* Number of non-volatile GPR registers */
     33#define R14 14 /* First non-volatile register to check in r14-r31 subset */
     34
     35long tm_signal_self_context_load(pid_t pid, long *gprs, double *fps, vector int *vms, vector int *vss);
     36
     37static sig_atomic_t fail, broken;
     38
     39/* Test only non-volatile general purpose registers, i.e. r14-r31 */
     40static long gprs[] = {
     41	/* First context will be set with these values, i.e. non-speculative */
     42	/* R14, R15, ... */
     43	 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18,
     44	/* Second context will be set with these values, i.e. speculative */
     45	/* R14, R15, ... */
     46	-1,-2,-3,-4,-5,-6,-7,-8,-9,-10,-11,-12,-13,-14,-15,-16,-17,-18
     47};
     48
     49static void signal_usr1(int signum, siginfo_t *info, void *uc)
     50{
     51	int i;
     52	ucontext_t *ucp = uc;
     53	ucontext_t *tm_ucp = ucp->uc_link;
     54
     55	/* Check first context. Print all mismatches. */
     56	for (i = 0; i < NV_GPR_REGS; i++) {
     57		fail = (ucp->uc_mcontext.gp_regs[R14 + i] != gprs[i]);
     58		if (fail) {
     59			broken = 1;
     60			printf("GPR%d (1st context) == %lu instead of %lu (expected)\n",
     61				R14 + i, ucp->uc_mcontext.gp_regs[R14 + i], gprs[i]);
     62		}
     63	}
     64
     65	/* Check second context. Print all mismatches. */
     66	for (i = 0; i < NV_GPR_REGS; i++) {
     67		fail = (tm_ucp->uc_mcontext.gp_regs[R14 + i] != gprs[NV_GPR_REGS + i]);
     68		if (fail) {
     69			broken = 1;
     70			printf("GPR%d (2nd context) == %lu instead of %lu (expected)\n",
     71				R14 + i, tm_ucp->uc_mcontext.gp_regs[R14 + i], gprs[NV_GPR_REGS + i]);
     72		}
     73	}
     74}
     75
     76static int tm_signal_context_chk_gpr()
     77{
     78	struct sigaction act;
     79	int i;
     80	long rc;
     81	pid_t pid = getpid();
     82
     83	SKIP_IF(!have_htm());
     84	SKIP_IF(htm_is_synthetic());
     85
     86	act.sa_sigaction = signal_usr1;
     87	sigemptyset(&act.sa_mask);
     88	act.sa_flags = SA_SIGINFO;
     89	if (sigaction(SIGUSR1, &act, NULL) < 0) {
     90		perror("sigaction sigusr1");
     91		exit(1);
     92	}
     93
     94	i = 0;
     95	while (i < MAX_ATTEMPT && !broken) {
     96                /*
     97                 * tm_signal_self_context_load will set both first and second
     98                 * contexts accordingly to the values passed through non-NULL
     99                 * array pointers to it, in that case 'gprs', and invoke the
    100                 * signal handler installed for SIGUSR1.
    101                 */
    102		rc = tm_signal_self_context_load(pid, gprs, NULL, NULL, NULL);
    103		FAIL_IF(rc != pid);
    104		i++;
    105	}
    106
    107	return broken;
    108}
    109
    110int main(void)
    111{
    112	return test_harness(tm_signal_context_chk_gpr, "tm_signal_context_chk_gpr");
    113}