cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
Log | Files | Refs | README | LICENSE | sfeed.txt

tm-signal-context-chk-fpu.c (3197B)

      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_FPU_REGS 18 /* Number of non-volatile FP registers */
     33#define FPR14 14 /* First non-volatile FP register to check in f14-31 subset */
     34
     35long tm_signal_self_context_load(pid_t pid, long *gprs, double *fps, vector int *vms, vector int *vss);
     36
     37/* Test only non-volatile registers, i.e. 18 fpr registers from f14 to f31 */
     38static double fps[] = {
     39	/* First context will be set with these values, i.e. non-speculative */
     40	 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18,
     41	/* Second context will be set with these values, i.e. speculative */
     42	-1,-2,-3,-4,-5,-6,-7,-8,-9,-10,-11,-12,-13,-14,-15,-16,-17,-18
     43};
     44
     45static sig_atomic_t fail, broken;
     46
     47static void signal_usr1(int signum, siginfo_t *info, void *uc)
     48{
     49	int i;
     50	ucontext_t *ucp = uc;
     51	ucontext_t *tm_ucp = ucp->uc_link;
     52
     53	for (i = 0; i < NV_FPU_REGS; i++) {
     54		/* Check first context. Print all mismatches. */
     55		fail = (ucp->uc_mcontext.fp_regs[FPR14 + i] != fps[i]);
     56		if (fail) {
     57			broken = 1;
     58			printf("FPR%d (1st context) == %g instead of %g (expected)\n",
     59				FPR14 + i, ucp->uc_mcontext.fp_regs[FPR14 + i], fps[i]);
     60		}
     61	}
     62
     63	for (i = 0; i < NV_FPU_REGS; i++) {
     64		/* Check second context. Print all mismatches. */
     65		fail = (tm_ucp->uc_mcontext.fp_regs[FPR14 + i] != fps[NV_FPU_REGS + i]);
     66		if (fail) {
     67			broken = 1;
     68			printf("FPR%d (2nd context) == %g instead of %g (expected)\n",
     69				FPR14 + i, tm_ucp->uc_mcontext.fp_regs[FPR14 + i], fps[NV_FPU_REGS + i]);
     70		}
     71	}
     72}
     73
     74static int tm_signal_context_chk_fpu()
     75{
     76	struct sigaction act;
     77	int i;
     78	long rc;
     79	pid_t pid = getpid();
     80
     81	SKIP_IF(!have_htm());
     82	SKIP_IF(htm_is_synthetic());
     83
     84	act.sa_sigaction = signal_usr1;
     85	sigemptyset(&act.sa_mask);
     86	act.sa_flags = SA_SIGINFO;
     87	if (sigaction(SIGUSR1, &act, NULL) < 0) {
     88		perror("sigaction sigusr1");
     89		exit(1);
     90	}
     91
     92	i = 0;
     93	while (i < MAX_ATTEMPT && !broken) {
     94		/*
     95		 * tm_signal_self_context_load will set both first and second
     96		 * contexts accordingly to the values passed through non-NULL
     97		 * array pointers to it, in that case 'fps', and invoke the
     98		 * signal handler installed for SIGUSR1.
     99		 */
    100		rc = tm_signal_self_context_load(pid, NULL, fps, NULL, NULL);
    101		FAIL_IF(rc != pid);
    102		i++;
    103	}
    104
    105	return (broken);
    106}
    107
    108int main(void)
    109{
    110	return test_harness(tm_signal_context_chk_fpu, "tm_signal_context_chk_fpu");
    111}