xref: /openbmc/linux/arch/hexagon/kernel/vm_entry.S (revision 9a6b55ac)
1/* SPDX-License-Identifier: GPL-2.0-only */
2/*
3 * Event entry/exit for Hexagon
4 *
5 * Copyright (c) 2010-2013, The Linux Foundation. All rights reserved.
6 */
7
8#include <asm/asm-offsets.h>  /*  assembly-safer versions of C defines */
9#include <asm/mem-layout.h>   /*  sigh, except for page_offset  */
10#include <asm/hexagon_vm.h>
11#include <asm/thread_info.h>
12
13/*
14 * Entry into guest-mode Linux under Hexagon Virtual Machine.
15 * Stack pointer points to event record - build pt_regs on top of it,
16 * set up a plausible C stack frame, and dispatch to the C handler.
17 * On return, do vmrte virtual instruction with SP where we started.
18 *
19 * VM Spec 0.5 uses a trap to fetch HVM record now.
20 */
21
22/*
23 * Save full register state, while setting up thread_info struct
24 * pointer derived from kernel stack pointer in THREADINFO_REG
25 * register, putting prior thread_info.regs pointer in a callee-save
26 * register (R24, which had better not ever be assigned to THREADINFO_REG),
27 * and updating thread_info.regs to point to current stack frame,
28 * so as to support nested events in kernel mode.
29 *
30 * As this is common code, we set the pt_regs system call number
31 * to -1 for all events.  It will be replaced with the system call
32 * number in the case where we decode a system call (trap0(#1)).
33 */
34
35#if CONFIG_HEXAGON_ARCH_VERSION < 4
36#define save_pt_regs()\
37 memd(R0 + #_PT_R3130) = R31:30; \
38 { memw(R0 + #_PT_R2928) = R28; \
39   R31 = memw(R0 + #_PT_ER_VMPSP); }\
40 { memw(R0 + #(_PT_R2928 + 4)) = R31; \
41   R31 = ugp; } \
42 { memd(R0 + #_PT_R2726) = R27:26; \
43   R30 = gp ; } \
44 memd(R0 + #_PT_R2524) = R25:24; \
45 memd(R0 + #_PT_R2322) = R23:22; \
46 memd(R0 + #_PT_R2120) = R21:20; \
47 memd(R0 + #_PT_R1918) = R19:18; \
48 memd(R0 + #_PT_R1716) = R17:16; \
49 memd(R0 + #_PT_R1514) = R15:14; \
50 memd(R0 + #_PT_R1312) = R13:12; \
51 { memd(R0 + #_PT_R1110) = R11:10; \
52   R15 = lc0; } \
53 { memd(R0 + #_PT_R0908) = R9:8; \
54   R14 = sa0; } \
55 { memd(R0 + #_PT_R0706) = R7:6; \
56   R13 = lc1; } \
57 { memd(R0 + #_PT_R0504) = R5:4; \
58   R12 = sa1; } \
59 { memd(R0 + #_PT_GPUGP) = R31:30; \
60   R11 = m1; \
61   R2.H = #HI(_THREAD_SIZE); } \
62 { memd(R0 + #_PT_LC0SA0) = R15:14; \
63   R10 = m0; \
64   R2.L = #LO(_THREAD_SIZE); } \
65 { memd(R0 + #_PT_LC1SA1) = R13:12; \
66   R15 = p3:0; \
67   R2 = neg(R2); } \
68 { memd(R0 + #_PT_M1M0) = R11:10; \
69   R14  = usr; \
70   R2 = and(R0,R2); } \
71 { memd(R0 + #_PT_PREDSUSR) =  R15:14; \
72   THREADINFO_REG = R2; } \
73 { r24 = memw(THREADINFO_REG + #_THREAD_INFO_PT_REGS); \
74   memw(THREADINFO_REG + #_THREAD_INFO_PT_REGS) = R0; \
75   R2 = #-1; } \
76 { memw(R0 + #_PT_SYSCALL_NR) = R2; \
77   R30 = #0; }
78#else
79/* V4+ */
80/* the # ## # syntax inserts a literal ## */
81#define save_pt_regs()\
82	{ memd(R0 + #_PT_R3130) = R31:30; \
83		R30 = memw(R0 + #_PT_ER_VMPSP); }\
84	{ memw(R0 + #_PT_R2928) = R28; \
85		memw(R0 + #(_PT_R2928 + 4)) = R30; }\
86	{ R31:30 = C11:10; \
87		memd(R0 + #_PT_R2726) = R27:26; \
88		memd(R0 + #_PT_R2524) = R25:24; }\
89	{ memd(R0 + #_PT_R2322) = R23:22; \
90		memd(R0 + #_PT_R2120) = R21:20; }\
91	{ memd(R0 + #_PT_R1918) = R19:18; \
92		memd(R0 + #_PT_R1716) = R17:16; }\
93	{ memd(R0 + #_PT_R1514) = R15:14; \
94		memd(R0 + #_PT_R1312) = R13:12; \
95		R17:16 = C13:12; }\
96	{ memd(R0 + #_PT_R1110) = R11:10; \
97		memd(R0 + #_PT_R0908) = R9:8; \
98	  R15:14 = C1:0; } \
99	{ memd(R0 + #_PT_R0706) = R7:6; \
100		memd(R0 + #_PT_R0504) = R5:4; \
101    R13:12 = C3:2; } \
102	{ memd(R0 + #_PT_GPUGP) = R31:30; \
103		memd(R0 + #_PT_LC0SA0) = R15:14; \
104	  R11:10 = C7:6; }\
105	{	THREADINFO_REG = and(R0, # ## #-_THREAD_SIZE); \
106		memd(R0 + #_PT_LC1SA1) = R13:12; \
107	  R15 = p3:0; }\
108	{ memd(R0 + #_PT_M1M0) = R11:10; \
109		memw(R0 + #_PT_PREDSUSR + 4) =  R15; }\
110	{ r24 = memw(THREADINFO_REG + #_THREAD_INFO_PT_REGS); \
111	  memw(THREADINFO_REG + #_THREAD_INFO_PT_REGS) = R0; \
112	  R2 = #-1; } \
113	{ memw(R0 + #_PT_SYSCALL_NR) = R2; \
114		memd(R0 + #_PT_CS1CS0) = R17:16; \
115	  R30 = #0; }
116#endif
117
118/*
119 * Restore registers and thread_info.regs state. THREADINFO_REG
120 * is assumed to still be sane, and R24 to have been correctly
121 * preserved. Don't restore R29 (SP) until later.
122 */
123
124#if CONFIG_HEXAGON_ARCH_VERSION < 4
125#define restore_pt_regs() \
126	{ memw(THREADINFO_REG + #_THREAD_INFO_PT_REGS) = R24; \
127	  R15:14 = memd(R0 + #_PT_PREDSUSR); } \
128	{ R11:10 = memd(R0 + #_PT_M1M0); \
129	  p3:0 = R15; } \
130	{ R13:12 = memd(R0 + #_PT_LC1SA1); \
131	  usr = R14; } \
132	{ R15:14 = memd(R0 + #_PT_LC0SA0); \
133	  m1 = R11; } \
134	{ R3:2 = memd(R0 + #_PT_R0302); \
135	  m0 = R10; } \
136	{ R5:4 = memd(R0 + #_PT_R0504); \
137	  lc1 = R13; } \
138	{ R7:6 = memd(R0 + #_PT_R0706); \
139	  sa1 = R12; } \
140	{ R9:8 = memd(R0 + #_PT_R0908); \
141	  lc0 = R15; } \
142	{ R11:10 = memd(R0 + #_PT_R1110); \
143	  sa0 = R14; } \
144	{ R13:12 = memd(R0 + #_PT_R1312); \
145	  R15:14 = memd(R0 + #_PT_R1514); } \
146	{ R17:16 = memd(R0 + #_PT_R1716); \
147	  R19:18 = memd(R0 + #_PT_R1918); } \
148	{ R21:20 = memd(R0 + #_PT_R2120); \
149	  R23:22 = memd(R0 + #_PT_R2322); } \
150	{ R25:24 = memd(R0 + #_PT_R2524); \
151	  R27:26 = memd(R0 + #_PT_R2726); } \
152	R31:30 = memd(R0 + #_PT_GPUGP); \
153	{ R28 = memw(R0 + #_PT_R2928); \
154	  ugp = R31; } \
155	{ R31:30 = memd(R0 + #_PT_R3130); \
156	  gp = R30; }
157#else
158/* V4+ */
159#define restore_pt_regs() \
160	{ memw(THREADINFO_REG + #_THREAD_INFO_PT_REGS) = R24; \
161	  R15:14 = memd(R0 + #_PT_PREDSUSR); } \
162	{ R11:10 = memd(R0 + #_PT_M1M0); \
163		R13:12 = memd(R0 + #_PT_LC1SA1); \
164		p3:0 = R15; } \
165	{ R15:14 = memd(R0 + #_PT_LC0SA0); \
166		R3:2 = memd(R0 + #_PT_R0302); \
167		usr = R14; } \
168	{ R5:4 = memd(R0 + #_PT_R0504); \
169		R7:6 = memd(R0 + #_PT_R0706); \
170		C7:6 = R11:10; }\
171	{ R9:8 = memd(R0 + #_PT_R0908); \
172		R11:10 = memd(R0 + #_PT_R1110); \
173    C3:2 = R13:12; }\
174	{ R13:12 = memd(R0 + #_PT_R1312); \
175	  R15:14 = memd(R0 + #_PT_R1514); \
176		C1:0 = R15:14; }\
177	{ R17:16 = memd(R0 + #_PT_R1716); \
178	  R19:18 = memd(R0 + #_PT_R1918); } \
179	{ R21:20 = memd(R0 + #_PT_R2120); \
180	  R23:22 = memd(R0 + #_PT_R2322); } \
181	{ R25:24 = memd(R0 + #_PT_R2524); \
182	  R27:26 = memd(R0 + #_PT_R2726); } \
183	R31:30 = memd(R0 + #_PT_CS1CS0); \
184	{ C13:12 = R31:30; \
185		R31:30 = memd(R0 + #_PT_GPUGP) ; \
186		R28 = memw(R0 + #_PT_R2928); }\
187	{ C11:10 = R31:30; \
188		R31:30 = memd(R0 + #_PT_R3130); }
189#endif
190
191	/*
192	 * Clears off enough space for the rest of pt_regs; evrec is a part
193	 * of pt_regs in HVM mode.  Save R0/R1, set handler's address in R1.
194	 * R0 is the address of pt_regs and is the parameter to save_pt_regs.
195	 */
196
197/*
198 * Since the HVM isn't automagically pushing the EVREC onto the stack anymore,
199 * we'll subract the entire size out and then fill it in ourselves.
200 * Need to save off R0, R1, R2, R3 immediately.
201 */
202
203#if CONFIG_HEXAGON_ARCH_VERSION < 4
204#define	vm_event_entry(CHandler) \
205	{ \
206		R29 = add(R29, #-(_PT_REGS_SIZE)); \
207		memd(R29 + #(_PT_R0100 + -_PT_REGS_SIZE)) = R1:0; \
208	} \
209	{ \
210		memd(R29 +#_PT_R0302) = R3:2; \
211	} \
212	trap1(#HVM_TRAP1_VMGETREGS); \
213	{ \
214		memd(R29 + #_PT_ER_VMEL) = R1:0; \
215		R0 = R29; \
216		R1.L = #LO(CHandler); \
217	} \
218	{ \
219		memd(R29 + #_PT_ER_VMPSP) = R3:2; \
220		R1.H = #HI(CHandler); \
221		jump event_dispatch; \
222	}
223#else
224/* V4+ */
225/* turn on I$ prefetch early */
226/* the # ## # syntax inserts a literal ## */
227#define	vm_event_entry(CHandler) \
228	{ \
229		R29 = add(R29, #-(_PT_REGS_SIZE)); \
230		memd(R29 + #(_PT_R0100 + -_PT_REGS_SIZE)) = R1:0; \
231		memd(R29 + #(_PT_R0302 + -_PT_REGS_SIZE)) = R3:2; \
232		R0 = usr; \
233	} \
234	{ \
235		memw(R29 + #_PT_PREDSUSR) = R0; \
236		R0 = setbit(R0, #16); \
237	} \
238	usr = R0; \
239	R1:0 = G1:0; \
240	{ \
241		memd(R29 + #_PT_ER_VMEL) = R1:0; \
242		R1 = # ## #(CHandler); \
243		R3:2 = G3:2; \
244	} \
245	{ \
246		R0 = R29; \
247		memd(R29 + #_PT_ER_VMPSP) = R3:2; \
248		jump event_dispatch; \
249	}
250#endif
251
252.text
253	/*
254	 * Do bulk save/restore in one place.
255	 * Adds a jump to dispatch latency, but
256	 * saves hundreds of bytes.
257	 */
258
259event_dispatch:
260	save_pt_regs()
261	callr	r1
262
263	/*
264	 * Coming back from the C-world, our thread info pointer
265	 * should be in the designated register (usually R19)
266	 *
267	 * If we were in kernel mode, we don't need to check scheduler
268	 * or signals if CONFIG_PREEMPT is not set.  If set, then it has
269	 * to jump to a need_resched kind of block.
270	 * BTW, CONFIG_PREEMPT is not supported yet.
271	 */
272
273#ifdef CONFIG_PREEMPT
274	R0 = #VM_INT_DISABLE
275	trap1(#HVM_TRAP1_VMSETIE)
276#endif
277
278	/*  "Nested control path" -- if the previous mode was kernel  */
279	{
280		R0 = memw(R29 + #_PT_ER_VMEST);
281		R26.L = #LO(do_work_pending);
282	}
283	{
284		P0 = tstbit(R0, #HVM_VMEST_UM_SFT);
285		if (!P0.new) jump:nt restore_all;
286		R26.H = #HI(do_work_pending);
287		R0 = #VM_INT_DISABLE;
288	}
289
290	/*
291	 * Check also the return from fork/system call, normally coming back from
292	 * user mode
293	 *
294	 * R26 needs to have do_work_pending, and R0 should have VM_INT_DISABLE
295	 */
296
297check_work_pending:
298	/*  Disable interrupts while checking TIF  */
299	trap1(#HVM_TRAP1_VMSETIE)
300	{
301		R0 = R29;  /*  regs should still be at top of stack  */
302		R1 = memw(THREADINFO_REG + #_THREAD_INFO_FLAGS);
303		callr R26;
304	}
305
306	{
307		P0 = cmp.eq(R0, #0); if (!P0.new) jump:nt check_work_pending;
308		R0 = #VM_INT_DISABLE;
309	}
310
311restore_all:
312	/*
313	 * Disable interrupts, if they weren't already, before reg restore.
314	 * R0 gets preloaded with #VM_INT_DISABLE before we get here.
315	 */
316	trap1(#HVM_TRAP1_VMSETIE)
317
318	/*  do the setregs here for VM 0.5  */
319	/*  R29 here should already be pointing at pt_regs  */
320	{
321		R1:0 = memd(R29 + #_PT_ER_VMEL);
322		R3:2 = memd(R29 + #_PT_ER_VMPSP);
323	}
324#if CONFIG_HEXAGON_ARCH_VERSION < 4
325	trap1(#HVM_TRAP1_VMSETREGS);
326#else
327	G1:0 = R1:0;
328	G3:2 = R3:2;
329#endif
330
331	R0 = R29
332	restore_pt_regs()
333	{
334		R1:0 = memd(R29 + #_PT_R0100);
335		R29 = add(R29, #_PT_REGS_SIZE);
336	}
337	trap1(#HVM_TRAP1_VMRTE)
338	/* Notreached */
339
340
341	.globl _K_enter_genex
342_K_enter_genex:
343	vm_event_entry(do_genex)
344
345	.globl _K_enter_interrupt
346_K_enter_interrupt:
347	vm_event_entry(arch_do_IRQ)
348
349	.globl _K_enter_trap0
350_K_enter_trap0:
351	vm_event_entry(do_trap0)
352
353	.globl _K_enter_machcheck
354_K_enter_machcheck:
355	vm_event_entry(do_machcheck)
356
357	.globl _K_enter_debug
358_K_enter_debug:
359	vm_event_entry(do_debug_exception)
360
361	.globl ret_from_fork
362ret_from_fork:
363	{
364		call schedule_tail
365		R26.H = #HI(do_work_pending);
366	}
367	{
368		P0 = cmp.eq(R24, #0);
369		R26.L = #LO(do_work_pending);
370		R0 = #VM_INT_DISABLE;
371	}
372	if (P0) jump check_work_pending
373	{
374		R0 = R25;
375		callr R24
376	}
377	{
378		jump check_work_pending
379		R0 = #VM_INT_DISABLE;
380	}
381