1 /*
2  * This file is subject to the terms and conditions of the GNU General Public
3  * License.  See the file "COPYING" in the main directory of this archive
4  * for more details.
5  *
6  * Copyright (C) 2001 - 2008 Tensilica Inc.
7  * Copyright (C) 2015 Cadence Design Systems Inc.
8  */
9 
10 #ifndef _XTENSA_PROCESSOR_H
11 #define _XTENSA_PROCESSOR_H
12 
13 #include <asm/core.h>
14 
15 #include <linux/compiler.h>
16 #include <linux/stringify.h>
17 #include <asm/ptrace.h>
18 #include <asm/types.h>
19 #include <asm/regs.h>
20 
21 /* Assertions. */
22 
23 #if (XCHAL_HAVE_WINDOWED != 1)
24 # error Linux requires the Xtensa Windowed Registers Option.
25 #endif
26 
27 /* Xtensa ABI requires stack alignment to be at least 16 */
28 
29 #define STACK_ALIGN (XCHAL_DATA_WIDTH > 16 ? XCHAL_DATA_WIDTH : 16)
30 
31 #define ARCH_SLAB_MINALIGN STACK_ALIGN
32 
33 /*
34  * User space process size: 1 GB.
35  * Windowed call ABI requires caller and callee to be located within the same
36  * 1 GB region. The C compiler places trampoline code on the stack for sources
37  * that take the address of a nested C function (a feature used by glibc), so
38  * the 1 GB requirement applies to the stack as well.
39  */
40 
41 #ifdef CONFIG_MMU
42 #define TASK_SIZE	__XTENSA_UL_CONST(0x40000000)
43 #else
44 #define TASK_SIZE	__XTENSA_UL_CONST(0xffffffff)
45 #endif
46 
47 #define STACK_TOP	TASK_SIZE
48 #define STACK_TOP_MAX	STACK_TOP
49 
50 /*
51  * General exception cause assigned to fake NMI. Fake NMI needs to be handled
52  * differently from other interrupts, but it uses common kernel entry/exit
53  * code.
54  */
55 
56 #define EXCCAUSE_MAPPED_NMI	62
57 
58 /*
59  * General exception cause assigned to debug exceptions. Debug exceptions go
60  * to their own vector, rather than the general exception vectors (user,
61  * kernel, double); and their specific causes are reported via DEBUGCAUSE
62  * rather than EXCCAUSE.  However it is sometimes convenient to redirect debug
63  * exceptions to the general exception mechanism.  To do this, an otherwise
64  * unused EXCCAUSE value was assigned to debug exceptions for this purpose.
65  */
66 
67 #define EXCCAUSE_MAPPED_DEBUG	63
68 
69 /*
70  * We use DEPC also as a flag to distinguish between double and regular
71  * exceptions. For performance reasons, DEPC might contain the value of
72  * EXCCAUSE for regular exceptions, so we use this definition to mark a
73  * valid double exception address.
74  * (Note: We use it in bgeui, so it should be 64, 128, or 256)
75  */
76 
77 #define VALID_DOUBLE_EXCEPTION_ADDRESS	64
78 
79 #define XTENSA_INT_LEVEL(intno) _XTENSA_INT_LEVEL(intno)
80 #define _XTENSA_INT_LEVEL(intno) XCHAL_INT##intno##_LEVEL
81 
82 #define XTENSA_INTLEVEL_MASK(level) _XTENSA_INTLEVEL_MASK(level)
83 #define _XTENSA_INTLEVEL_MASK(level) (XCHAL_INTLEVEL##level##_MASK)
84 
85 #define XTENSA_INTLEVEL_ANDBELOW_MASK(l) _XTENSA_INTLEVEL_ANDBELOW_MASK(l)
86 #define _XTENSA_INTLEVEL_ANDBELOW_MASK(l) (XCHAL_INTLEVEL##l##_ANDBELOW_MASK)
87 
88 #define PROFILING_INTLEVEL XTENSA_INT_LEVEL(XCHAL_PROFILING_INTERRUPT)
89 
90 /* LOCKLEVEL defines the interrupt level that masks all
91  * general-purpose interrupts.
92  */
93 #if defined(CONFIG_XTENSA_FAKE_NMI) && defined(XCHAL_PROFILING_INTERRUPT)
94 #define LOCKLEVEL (PROFILING_INTLEVEL - 1)
95 #else
96 #define LOCKLEVEL XCHAL_EXCM_LEVEL
97 #endif
98 
99 #define TOPLEVEL XCHAL_EXCM_LEVEL
100 #define XTENSA_FAKE_NMI (LOCKLEVEL < TOPLEVEL)
101 
102 /* WSBITS and WBBITS are the width of the WINDOWSTART and WINDOWBASE
103  * registers
104  */
105 #define WSBITS  (XCHAL_NUM_AREGS / 4)      /* width of WINDOWSTART in bits */
106 #define WBBITS  (XCHAL_NUM_AREGS_LOG2 - 2) /* width of WINDOWBASE in bits */
107 
108 #ifndef __ASSEMBLY__
109 
110 /* Build a valid return address for the specified call winsize.
111  * winsize must be 1 (call4), 2 (call8), or 3 (call12)
112  */
113 #define MAKE_RA_FOR_CALL(ra,ws)   (((ra) & 0x3fffffff) | (ws) << 30)
114 
115 /* Convert return address to a valid pc
116  * Note: We assume that the stack pointer is in the same 1GB ranges as the ra
117  */
118 #define MAKE_PC_FROM_RA(ra,sp)    (((ra) & 0x3fffffff) | ((sp) & 0xc0000000))
119 
120 /* Spill slot location for the register reg in the spill area under the stack
121  * pointer sp. reg must be in the range [0..4).
122  */
123 #define SPILL_SLOT(sp, reg) (*(((unsigned long *)(sp)) - 4 + (reg)))
124 
125 /* Spill slot location for the register reg in the spill area under the stack
126  * pointer sp for the call8. reg must be in the range [4..8).
127  */
128 #define SPILL_SLOT_CALL8(sp, reg) (*(((unsigned long *)(sp)) - 12 + (reg)))
129 
130 /* Spill slot location for the register reg in the spill area under the stack
131  * pointer sp for the call12. reg must be in the range [4..12).
132  */
133 #define SPILL_SLOT_CALL12(sp, reg) (*(((unsigned long *)(sp)) - 16 + (reg)))
134 
135 typedef struct {
136 	unsigned long seg;
137 } mm_segment_t;
138 
139 struct thread_struct {
140 
141 	/* kernel's return address and stack pointer for context switching */
142 	unsigned long ra; /* kernel's a0: return address and window call size */
143 	unsigned long sp; /* kernel's a1: stack pointer */
144 
145 	mm_segment_t current_ds;    /* see uaccess.h for example uses */
146 
147 	/* struct xtensa_cpuinfo info; */
148 
149 	unsigned long bad_vaddr; /* last user fault */
150 	unsigned long bad_uaddr; /* last kernel fault accessing user space */
151 	unsigned long error_code;
152 #ifdef CONFIG_HAVE_HW_BREAKPOINT
153 	struct perf_event *ptrace_bp[XCHAL_NUM_IBREAK];
154 	struct perf_event *ptrace_wp[XCHAL_NUM_DBREAK];
155 #endif
156 	/* Make structure 16 bytes aligned. */
157 	int align[0] __attribute__ ((aligned(16)));
158 };
159 
160 /* This decides where the kernel will search for a free chunk of vm
161  * space during mmap's.
162  */
163 #define TASK_UNMAPPED_BASE	(TASK_SIZE / 2)
164 
165 #define INIT_THREAD  \
166 {									\
167 	ra:		0, 						\
168 	sp:		sizeof(init_stack) + (long) &init_stack,	\
169 	current_ds:	{0},						\
170 	/*info:		{0}, */						\
171 	bad_vaddr:	0,						\
172 	bad_uaddr:	0,						\
173 	error_code:	0,						\
174 }
175 
176 
177 /*
178  * Do necessary setup to start up a newly executed thread.
179  * Note: When windowed ABI is used for userspace we set-up ps
180  *       as if we did a call4 to the new pc.
181  *       set_thread_state in signal.c depends on it.
182  */
183 #if IS_ENABLED(CONFIG_USER_ABI_CALL0)
184 #define USER_PS_VALUE ((USER_RING << PS_RING_SHIFT) |			\
185 		       (1 << PS_UM_BIT) |				\
186 		       (1 << PS_EXCM_BIT))
187 #else
188 #define USER_PS_VALUE (PS_WOE_MASK |					\
189 		       (1 << PS_CALLINC_SHIFT) |			\
190 		       (USER_RING << PS_RING_SHIFT) |			\
191 		       (1 << PS_UM_BIT) |				\
192 		       (1 << PS_EXCM_BIT))
193 #endif
194 
195 /* Clearing a0 terminates the backtrace. */
196 #define start_thread(regs, new_pc, new_sp) \
197 	do { \
198 		unsigned long syscall = (regs)->syscall; \
199 		memset((regs), 0, sizeof(*(regs))); \
200 		(regs)->pc = (new_pc); \
201 		(regs)->ps = USER_PS_VALUE; \
202 		(regs)->areg[1] = (new_sp); \
203 		(regs)->areg[0] = 0; \
204 		(regs)->wmask = 1; \
205 		(regs)->depc = 0; \
206 		(regs)->windowbase = 0; \
207 		(regs)->windowstart = 1; \
208 		(regs)->syscall = syscall; \
209 	} while (0)
210 
211 /* Forward declaration */
212 struct task_struct;
213 struct mm_struct;
214 
215 /* Free all resources held by a thread. */
216 #define release_thread(thread) do { } while(0)
217 
218 extern unsigned long get_wchan(struct task_struct *p);
219 
220 #define KSTK_EIP(tsk)		(task_pt_regs(tsk)->pc)
221 #define KSTK_ESP(tsk)		(task_pt_regs(tsk)->areg[1])
222 
223 #define cpu_relax()  barrier()
224 
225 /* Special register access. */
226 
227 #define xtensa_set_sr(x, sr) \
228 	({ \
229 	 unsigned int v = (unsigned int)(x); \
230 	 __asm__ __volatile__ ("wsr %0, "__stringify(sr) :: "a"(v)); \
231 	 })
232 
233 #define xtensa_get_sr(sr) \
234 	({ \
235 	 unsigned int v; \
236 	 __asm__ __volatile__ ("rsr %0, "__stringify(sr) : "=a"(v)); \
237 	 v; \
238 	 })
239 
240 #if XCHAL_HAVE_EXTERN_REGS
241 
242 static inline void set_er(unsigned long value, unsigned long addr)
243 {
244 	asm volatile ("wer %0, %1" : : "a" (value), "a" (addr) : "memory");
245 }
246 
247 static inline unsigned long get_er(unsigned long addr)
248 {
249 	register unsigned long value;
250 	asm volatile ("rer %0, %1" : "=a" (value) : "a" (addr) : "memory");
251 	return value;
252 }
253 
254 #endif /* XCHAL_HAVE_EXTERN_REGS */
255 
256 #endif	/* __ASSEMBLY__ */
257 #endif	/* _XTENSA_PROCESSOR_H */
258