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 <string.h>
23 #include <signal.h>
24 #include <unistd.h>
25 
26 #include <altivec.h>
27 
28 #include "utils.h"
29 #include "tm.h"
30 
31 #define MAX_ATTEMPT 500000
32 
33 #define NV_VSX_REGS 12 /* Number of VSX registers to check. */
34 #define VSX20 20 /* First VSX register to check in vsr20-vsr31 subset */
35 #define FPR20 20 /* FPR20 overlaps VSX20 most significant doubleword */
36 
37 long tm_signal_self_context_load(pid_t pid, long *gprs, double *fps, vector int *vms, vector int *vss);
38 
39 static sig_atomic_t fail, broken;
40 
41 /* Test only 12 vsx registers from vsr20 to vsr31 */
42 vector int vsxs[] = {
43 	/* First context will be set with these values, i.e. non-speculative */
44 	/* VSX20     ,  VSX21      , ... */
45 	{ 1, 2, 3, 4},{ 5, 6, 7, 8},{ 9,10,11,12},
46 	{13,14,15,16},{17,18,19,20},{21,22,23,24},
47 	{25,26,27,28},{29,30,31,32},{33,34,35,36},
48 	{37,38,39,40},{41,42,43,44},{45,46,47,48},
49 	/* Second context will be set with these values, i.e. speculative */
50 	/* VSX20         ,  VSX21          , ... */
51 	{-1, -2, -3, -4 },{-5, -6, -7, -8 },{-9, -10,-11,-12},
52 	{-13,-14,-15,-16},{-17,-18,-19,-20},{-21,-22,-23,-24},
53 	{-25,-26,-27,-28},{-29,-30,-31,-32},{-33,-34,-35,-36},
54 	{-37,-38,-39,-40},{-41,-42,-43,-44},{-45,-46,-47,-48}
55 };
56 
signal_usr1(int signum,siginfo_t * info,void * uc)57 static void signal_usr1(int signum, siginfo_t *info, void *uc)
58 {
59 	int i, j;
60 	uint8_t vsx[sizeof(vector int)];
61 	uint8_t vsx_tm[sizeof(vector int)];
62 	ucontext_t *ucp = uc;
63 	ucontext_t *tm_ucp = ucp->uc_link;
64 
65 	/*
66 	 * FP registers and VMX registers overlap the VSX registers.
67 	 *
68 	 * FP registers (f0-31) overlap the most significant 64 bits of VSX
69 	 * registers vsr0-31, whilst VMX registers vr0-31, being 128-bit like
70 	 * the VSX registers, overlap fully the other half of VSX registers,
71 	 * i.e. vr0-31 overlaps fully vsr32-63.
72 	 *
73 	 * Due to compatibility and historical reasons (VMX/Altivec support
74 	 * appeared first on the architecture), VMX registers vr0-31 (so VSX
75 	 * half vsr32-63 too) are stored right after the v_regs pointer, in an
76 	 * area allocated for 'vmx_reverse' array (please see
77 	 * arch/powerpc/include/uapi/asm/sigcontext.h for details about the
78 	 * mcontext_t structure on Power).
79 	 *
80 	 * The other VSX half (vsr0-31) is hence stored below vr0-31/vsr32-63
81 	 * registers, but only the least significant 64 bits of vsr0-31. The
82 	 * most significant 64 bits of vsr0-31 (f0-31), as it overlaps the FP
83 	 * registers, is kept in fp_regs.
84 	 *
85 	 * v_regs is a 16 byte aligned pointer at the start of vmx_reserve
86 	 * (vmx_reserve may or may not be 16 aligned) where the v_regs structure
87 	 * exists, so v_regs points to where vr0-31 / vsr32-63 registers are
88 	 * fully stored. Since v_regs type is elf_vrregset_t, v_regs + 1
89 	 * skips all the slots used to store vr0-31 / vsr32-64 and points to
90 	 * part of one VSX half, i.e. v_regs + 1 points to the least significant
91 	 * 64 bits of vsr0-31. The other part of this half (the most significant
92 	 * part of vsr0-31) is stored in fp_regs.
93 	 *
94 	 */
95 	/* Get pointer to least significant doubleword of vsr0-31 */
96 	long *vsx_ptr = (long *)(ucp->uc_mcontext.v_regs + 1);
97 	long *tm_vsx_ptr = (long *)(tm_ucp->uc_mcontext.v_regs + 1);
98 
99 	/* Check first context. Print all mismatches. */
100 	for (i = 0; i < NV_VSX_REGS; i++) {
101 		/*
102 		 * Copy VSX most significant doubleword from fp_regs and
103 		 * copy VSX least significant one from 64-bit slots below
104 		 * saved VMX registers.
105 		 */
106 		memcpy(vsx, &ucp->uc_mcontext.fp_regs[FPR20 + i], 8);
107 		memcpy(vsx + 8, &vsx_ptr[VSX20 + i], 8);
108 
109 		fail = memcmp(vsx, &vsxs[i], sizeof(vector int));
110 
111 		if (fail) {
112 			broken = 1;
113 			printf("VSX%d (1st context) == 0x", VSX20 + i);
114 			for (j = 0; j < 16; j++)
115 				printf("%02x", vsx[j]);
116 			printf(" instead of 0x");
117 			for (j = 0; j < 4; j++)
118 				printf("%08x", vsxs[i][j]);
119 			printf(" (expected)\n");
120 		}
121 	}
122 
123 	/* Check second context. Print all mismatches. */
124 	for (i = 0; i < NV_VSX_REGS; i++) {
125 		/*
126 		 * Copy VSX most significant doubleword from fp_regs and
127 		 * copy VSX least significant one from 64-bit slots below
128 		 * saved VMX registers.
129 		 */
130 		memcpy(vsx_tm, &tm_ucp->uc_mcontext.fp_regs[FPR20 + i], 8);
131 		memcpy(vsx_tm + 8, &tm_vsx_ptr[VSX20 + i], 8);
132 
133 		fail = memcmp(vsx_tm, &vsxs[NV_VSX_REGS + i], sizeof(vector int));
134 
135 		if (fail) {
136 			broken = 1;
137 			printf("VSX%d (2nd context) == 0x", VSX20 + i);
138 			for (j = 0; j < 16; j++)
139 				printf("%02x", vsx_tm[j]);
140 			printf(" instead of 0x");
141 			for (j = 0; j < 4; j++)
142 				printf("%08x", vsxs[NV_VSX_REGS + i][j]);
143 			printf("(expected)\n");
144 		}
145 	}
146 }
147 
tm_signal_context_chk()148 static int tm_signal_context_chk()
149 {
150 	struct sigaction act;
151 	int i;
152 	long rc;
153 	pid_t pid = getpid();
154 
155 	SKIP_IF(!have_htm());
156 	SKIP_IF(htm_is_synthetic());
157 
158 	act.sa_sigaction = signal_usr1;
159 	sigemptyset(&act.sa_mask);
160 	act.sa_flags = SA_SIGINFO;
161 	if (sigaction(SIGUSR1, &act, NULL) < 0) {
162 		perror("sigaction sigusr1");
163 		exit(1);
164 	}
165 
166 	i = 0;
167 	while (i < MAX_ATTEMPT && !broken) {
168                /*
169                 * tm_signal_self_context_load will set both first and second
170                 * contexts accordingly to the values passed through non-NULL
171                 * array pointers to it, in that case 'vsxs', and invoke the
172                 * signal handler installed for SIGUSR1.
173                 */
174 		rc = tm_signal_self_context_load(pid, NULL, NULL, NULL, vsxs);
175 		FAIL_IF(rc != pid);
176 		i++;
177 	}
178 
179 	return (broken);
180 }
181 
main(void)182 int main(void)
183 {
184 	return test_harness(tm_signal_context_chk, "tm_signal_context_chk_vsx");
185 }
186