1/* SPDX-License-Identifier: GPL-2.0-or-later */
2/*
3 * HPMC (High Priority Machine Check) handler.
4 *
5 * Copyright (C) 1999 Philipp Rumpf <prumpf@tux.org>
6 * Copyright (C) 1999 Hewlett-Packard (Frank Rowand)
7 * Copyright (C) 2000 Hewlett-Packard (John Marvin)
8 */
9
10
11/*
12 * This HPMC handler retrieves the HPMC pim data, resets IO and
13 * returns to the default trap handler with code set to 1 (HPMC).
14 * The default trap handler calls handle interruption, which
15 * does a stack and register dump. This at least allows kernel
16 * developers to get back to C code in virtual mode, where they
17 * have the option to examine and print values from memory that
18 * would help in debugging an HPMC caused by a software bug.
19 *
20 * There is more to do here:
21 *
22 *      1) On MP systems we need to synchronize processors
23 *         before calling pdc/iodc.
24 *      2) We should be checking the system state and not
25 *         returning to the fault handler if things are really
26 *         bad.
27 *
28 */
29
30	.level		1.1
31
32#include <asm/assembly.h>
33#include <asm/pdc.h>
34#include <asm/psw.h>
35
36#include <linux/linkage.h>
37#include <linux/init.h>
38
39	/*
40	 * stack for os_hpmc, the HPMC handler.
41	 * buffer for IODC procedures (for the HPMC handler).
42	 *
43	 * IODC requires 7K byte stack.  That leaves 1K byte for os_hpmc.
44	 */
45
46	.import toc_stack,data
47#define hpmc_stack	toc_stack	/* re-use the TOC stack */
48
49#define HPMC_IODC_BUF_SIZE 0x8000
50
51	__PAGE_ALIGNED_BSS
52	.align 4096
53hpmc_iodc_buf:
54	.block HPMC_IODC_BUF_SIZE
55
56	.section .bss
57	.align 8
58hpmc_raddr:
59	.block 128
60
61#define HPMC_PIM_DATA_SIZE 896 /* Enough to hold all architected 2.0 state */
62
63	.section .bss
64	.align 8
65ENTRY(hpmc_pim_data)
66	.block HPMC_PIM_DATA_SIZE
67END(hpmc_pim_data)
68
69	.text
70
71	.import intr_save, code
72	.align 16
73ENTRY(os_hpmc)
74.os_hpmc:
75
76	/*
77	 * registers modified:
78	 *
79	 *   Using callee saves registers without saving them.  The
80	 *   original values are in the pim dump if we need them.
81	 *
82	 *   r2   (rp)  return pointer
83	 *   r3   address of PDCE_PROC
84	 *   r4   scratch
85	 *   r5   scratch
86	 *   r23  (arg3) procedure arg
87	 *   r24  (arg2) procedure arg
88	 *   r25  (arg1) procedure arg
89	 *   r26  (arg0) procedure arg
90	 *   r30  (sp)   stack pointer
91	 *
92	 * registers read:
93	 *
94	 *   r26  contains address of PDCE_PROC on entry
95	 *   r28  (ret0) return value from procedure
96	 */
97
98	copy    arg0, %r3       /* save address of PDCE_PROC */
99
100	/*
101	 *  disable nested HPMCs
102	 *
103	 * Increment os_hpmc checksum to invalidate it.
104	 * Do this before turning the PSW M bit off.
105	 */
106
107	mfctl   %cr14, %r4
108	ldw     52(%r4),%r5
109	addi    1,%r5,%r5
110	stw     %r5,52(%r4)
111
112	/* MP_FIXME: synchronize all processors. */
113
114	/* Setup stack pointer. */
115
116	load32	PA(hpmc_stack),sp
117
118	ldo     128(sp),sp /* leave room for arguments */
119
120	/*
121	 * Most PDC routines require that the M bit be off.
122	 * So turn on the Q bit and turn off the M bit.
123	 */
124
125	ldi     PSW_SM_Q,%r4                   /* PSW Q on, PSW M off */
126	mtctl   %r4,ipsw
127	mtctl   %r0,pcsq
128	mtctl   %r0,pcsq
129	load32	PA(os_hpmc_1),%r4
130	mtctl   %r4,pcoq
131	ldo     4(%r4),%r4
132	mtctl   %r4,pcoq
133	rfi
134	nop
135
136os_hpmc_1:
137
138	/* Call PDC_PIM to get HPMC pim info */
139
140	/*
141	 * Note that on some newer boxes, PDC_PIM must be called
142	 * before PDC_IO if you want IO to be reset. PDC_PIM sets
143	 * a flag that PDC_IO examines.
144	 */
145
146	ldo     PDC_PIM(%r0), arg0
147	ldo     PDC_PIM_HPMC(%r0),arg1          /* Transfer HPMC data */
148	load32	PA(hpmc_raddr),arg2
149	load32	PA(hpmc_pim_data),arg3
150	load32	HPMC_PIM_DATA_SIZE,%r4
151	stw     %r4,-52(sp)
152
153	ldil    L%PA(os_hpmc_2), rp
154	bv      (r3)                            /* call pdce_proc */
155	ldo     R%PA(os_hpmc_2)(rp), rp
156
157os_hpmc_2:
158	comib,<>  0,ret0, os_hpmc_fail
159
160	/* Reset IO by calling the hversion dependent PDC_IO routine */
161
162	ldo     PDC_IO(%r0),arg0
163	ldo     0(%r0),arg1                     /* log IO errors */
164	ldo     0(%r0),arg2                     /* reserved */
165	ldo     0(%r0),arg3                     /* reserved */
166	stw     %r0,-52(sp)                     /* reserved */
167
168	ldil    L%PA(os_hpmc_3),rp
169	bv      (%r3)                           /* call pdce_proc */
170	ldo     R%PA(os_hpmc_3)(rp),rp
171
172os_hpmc_3:
173
174	/* FIXME? Check for errors from PDC_IO (-1 might be OK) */
175
176	/*
177	 * Initialize the IODC console device (HPA,SPA, path etc.
178	 * are stored on page 0.
179	 */
180
181	/*
182	 * Load IODC into hpmc_iodc_buf by calling PDC_IODC.
183	 * Note that PDC_IODC handles flushing the appropriate
184	 * data and instruction cache lines.
185	 */
186
187	ldo     PDC_IODC(%r0),arg0
188	ldo     PDC_IODC_READ(%r0),arg1
189	load32	PA(hpmc_raddr),arg2
190	ldw     BOOT_CONSOLE_HPA_OFFSET(%r0),arg3 /* console hpa */
191	ldo     PDC_IODC_RI_INIT(%r0),%r4
192	stw     %r4,-52(sp)
193	load32	PA(hpmc_iodc_buf),%r4
194	stw     %r4,-56(sp)
195	load32	HPMC_IODC_BUF_SIZE,%r4
196	stw     %r4,-60(sp)
197
198	ldil    L%PA(os_hpmc_4),rp
199	bv      (%r3)                            /* call pdce_proc */
200	ldo     R%PA(os_hpmc_4)(rp),rp
201
202os_hpmc_4:
203	comib,<>  0,ret0,os_hpmc_fail
204
205	/* Call the entry init (just loaded by PDC_IODC) */
206
207	ldw     BOOT_CONSOLE_HPA_OFFSET(%r0),arg0  /* console hpa */
208	ldo     ENTRY_INIT_MOD_DEV(%r0), arg1
209	ldw     BOOT_CONSOLE_SPA_OFFSET(%r0),arg2  /* console spa */
210	depi    0,31,11,arg2                       /* clear bits 21-31    */
211	ldo     BOOT_CONSOLE_PATH_OFFSET(%r0),arg3 /* console path */
212	load32	PA(hpmc_raddr),%r4
213	stw     %r4, -52(sp)
214	stw     %r0, -56(sp)                    /* HV                  */
215	stw     %r0, -60(sp)                    /* HV                  */
216	stw     %r0, -64(sp)                    /* HV                  */
217	stw     %r0, -68(sp)                    /* lang, must be zero  */
218
219	load32	PA(hpmc_iodc_buf),%r5
220	ldil    L%PA(os_hpmc_5),rp
221	bv      (%r5)
222	ldo     R%PA(os_hpmc_5)(rp),rp
223
224os_hpmc_5:
225	comib,<>  0,ret0,os_hpmc_fail
226
227	/* Prepare to call intr_save */
228
229	/*
230	 * Load kernel page directory (load into user also, since
231	 * we don't intend to ever return to user land anyway)
232	 */
233
234	load32		PA(swapper_pg_dir),%r4
235	mtctl		%r4,%cr24	/* Initialize kernel root pointer */
236	mtctl		%r4,%cr25	/* Initialize user root pointer */
237
238	/* Clear sr4-sr7 */
239
240	mtsp	%r0, %sr4
241	mtsp	%r0, %sr5
242	mtsp	%r0, %sr6
243	mtsp	%r0, %sr7
244
245	tovirt_r1 %r30      /* make sp virtual */
246
247	rsm     PSW_SM_Q,%r0           /* Clear Q bit */
248	ldi     1,%r8       /* Set trap code to "1" for HPMC */
249	load32	PA(intr_save),%r1
250	be      0(%sr7,%r1)
251	nop
252
253os_hpmc_fail:
254
255	/*
256	 * Reset the system
257	 *
258	 * Some systems may lockup from a broadcast reset, so try the
259	 * hversion PDC_BROADCAST_RESET() first.
260	 * MP_FIXME: reset all processors if more than one central bus.
261	 */
262
263	/* PDC_BROADCAST_RESET() */
264
265	ldo     PDC_BROADCAST_RESET(%r0),arg0
266	ldo     0(%r0),arg1                     /* do reset */
267
268	ldil    L%PA(os_hpmc_6),rp
269	bv      (%r3)                           /* call pdce_proc */
270	ldo     R%PA(os_hpmc_6)(rp),rp
271
272os_hpmc_6:
273
274	/*
275	 * possible return values:
276	 *  -1  non-existent procedure
277	 *  -2  non-existent option
278	 *  -16 unaligned stack
279	 *
280	 * If call returned, do a broadcast reset.
281	 */
282
283	ldil    L%0xfffc0000,%r4        /* IO_BROADCAST */
284	ldo     5(%r0),%r5
285	stw     %r5,48(%r4)             /*  CMD_RESET to IO_COMMAND offset */
286
287	b .
288	nop
289	.align 16	/* make function length multiple of 16 bytes */
290