1/*
  2 * Copyright 2010 Tilera Corporation. All Rights Reserved.
  3 *
  4 *   This program is free software; you can redistribute it and/or
  5 *   modify it under the terms of the GNU General Public License
  6 *   as published by the Free Software Foundation, version 2.
  7 *
  8 *   This program is distributed in the hope that it will be useful, but
  9 *   WITHOUT ANY WARRANTY; without even the implied warranty of
 10 *   MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
 11 *   NON INFRINGEMENT.  See the GNU General Public License for
 12 *   more details.
 13 */
 14
 15#include <linux/linkage.h>
 16#include <asm/ptrace.h>
 17#include <asm/asm-offsets.h>
 18#include <arch/spr_def.h>
 19#include <asm/processor.h>
 20#include <asm/switch_to.h>
 21
 22/*
 23 * See <asm/system.h>; called with prev and next task_struct pointers.
 24 * "prev" is returned in r0 for _switch_to and also for ret_from_fork.
 25 *
 26 * We want to save pc/sp in "prev", and get the new pc/sp from "next".
 27 * We also need to save all the callee-saved registers on the stack.
 28 *
 29 * Intel enables/disables access to the hardware cycle counter in
 30 * seccomp (secure computing) environments if necessary, based on
 31 * has_secure_computing().  We might want to do this at some point,
 32 * though it would require virtualizing the other SPRs under WORLD_ACCESS.
 33 *
 34 * Since we're saving to the stack, we omit sp from this list.
 35 * And for parallels with other architectures, we save lr separately,
 36 * in the thread_struct itself (as the "pc" field).
 37 *
 38 * This code also needs to be aligned with process.c copy_thread()
 39 */
 40
 41#if CALLEE_SAVED_REGS_COUNT != 24
 42# error Mismatch between <asm/system.h> and kernel/entry.S
 43#endif
 44#define FRAME_SIZE ((2 + CALLEE_SAVED_REGS_COUNT) * 4)
 45
 46#define SAVE_REG(r) { sw r12, r; addi r12, r12, 4 }
 47#define LOAD_REG(r) { lw r, r12; addi r12, r12, 4 }
 48#define FOR_EACH_CALLEE_SAVED_REG(f)					\
 49							f(r30); f(r31); \
 50	f(r32); f(r33); f(r34); f(r35);	f(r36); f(r37); f(r38); f(r39); \
 51	f(r40); f(r41); f(r42); f(r43); f(r44); f(r45); f(r46); f(r47); \
 52	f(r48); f(r49); f(r50); f(r51); f(r52);
 53
 54STD_ENTRY_SECTION(__switch_to, .sched.text)
 55	{
 56	  move r10, sp
 57	  sw sp, lr
 58	  addi sp, sp, -FRAME_SIZE
 59	}
 60	{
 61	  addi r11, sp, 4
 62	  addi r12, sp, 8
 63	}
 64	{
 65	  sw r11, r10
 66	  addli r4, r1, TASK_STRUCT_THREAD_KSP_OFFSET
 67	}
 68	{
 69	  lw r13, r4   /* Load new sp to a temp register early. */
 70	  addli r3, r0, TASK_STRUCT_THREAD_KSP_OFFSET
 71	}
 72	FOR_EACH_CALLEE_SAVED_REG(SAVE_REG)
 73	{
 74	  sw r3, sp
 75	  addli r3, r0, TASK_STRUCT_THREAD_PC_OFFSET
 76	}
 77	{
 78	  sw r3, lr
 79	  addli r4, r1, TASK_STRUCT_THREAD_PC_OFFSET
 80	}
 81	{
 82	  lw lr, r4
 83	  addi r12, r13, 8
 84	}
 85	{
 86	  /* Update sp and ksp0 simultaneously to avoid backtracer warnings. */
 87	  move sp, r13
 88	  mtspr SPR_SYSTEM_SAVE_K_0, r2
 89	}
 90	FOR_EACH_CALLEE_SAVED_REG(LOAD_REG)
 91.L__switch_to_pc:
 92	{
 93	  addi sp, sp, FRAME_SIZE
 94	  jrp lr   /* r0 is still valid here, so return it */
 95	}
 96	STD_ENDPROC(__switch_to)
 97
 98/* Return a suitable address for the backtracer for suspended threads */
 99STD_ENTRY_SECTION(get_switch_to_pc, .sched.text)
100	lnk r0
101	{
102	  addli r0, r0, .L__switch_to_pc - .
103	  jrp lr
104	}
105	STD_ENDPROC(get_switch_to_pc)
106
107STD_ENTRY(get_pt_regs)
108	.irp reg, r0, r1, r2, r3, r4, r5, r6, r7, \
109		 r8, r9, r10, r11, r12, r13, r14, r15, \
110		 r16, r17, r18, r19, r20, r21, r22, r23, \
111		 r24, r25, r26, r27, r28, r29, r30, r31, \
112		 r32, r33, r34, r35, r36, r37, r38, r39, \
113		 r40, r41, r42, r43, r44, r45, r46, r47, \
114		 r48, r49, r50, r51, r52, tp, sp
115	{
116	 sw r0, \reg
117	 addi r0, r0, 4
118	}
119	.endr
120	{
121	 sw r0, lr
122	 addi r0, r0, PTREGS_OFFSET_PC - PTREGS_OFFSET_LR
123	}
124	lnk r1
125	{
126	 sw r0, r1
127	 addi r0, r0, PTREGS_OFFSET_EX1 - PTREGS_OFFSET_PC
128	}
129	mfspr r1, INTERRUPT_CRITICAL_SECTION
130	shli r1, r1, SPR_EX_CONTEXT_1_1__ICS_SHIFT
131	ori r1, r1, KERNEL_PL
132	{
133	 sw r0, r1
134	 addi r0, r0, PTREGS_OFFSET_FAULTNUM - PTREGS_OFFSET_EX1
135	}
136	{
137	 sw r0, zero       /* clear faultnum */
138	 addi r0, r0, PTREGS_OFFSET_ORIG_R0 - PTREGS_OFFSET_FAULTNUM
139	}
140	{
141	 sw r0, zero       /* clear orig_r0 */
142	 addli r0, r0, -PTREGS_OFFSET_ORIG_R0    /* restore r0 to base */
143	}
144	jrp lr
145	STD_ENDPROC(get_pt_regs)