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authorPaul Mundt <lethal@linux-sh.org>2007-11-19 05:00:41 -0500
committerPaul Mundt <lethal@linux-sh.org>2008-01-27 23:18:47 -0500
commit7cfee5ac3edd3b4226018da6aad87334793cb1c5 (patch)
treefc0d75fea89fbbc4d5f6fb5afd209cd9eec2b04a /arch/sh
parent3eeffb32049d4b43b01211a79496cfdaac0c33ad (diff)
sh: Move over sh64 switch_to and stack unwinder.
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
Diffstat (limited to 'arch/sh')
-rw-r--r--arch/sh/kernel/cpu/sh5/Makefile4
-rw-r--r--arch/sh/kernel/cpu/sh5/switchto.S198
-rw-r--r--arch/sh/kernel/cpu/sh5/unwind.c326
3 files changed, 527 insertions, 1 deletions
diff --git a/arch/sh/kernel/cpu/sh5/Makefile b/arch/sh/kernel/cpu/sh5/Makefile
index 9778f9bdff3a..7ea10732b5cc 100644
--- a/arch/sh/kernel/cpu/sh5/Makefile
+++ b/arch/sh/kernel/cpu/sh5/Makefile
@@ -1 +1,3 @@
1obj-y := entry.o 1obj-y := entry.o switchto.o
2
3obj-$(CONFIG_KALLSYMS) += unwind.o
diff --git a/arch/sh/kernel/cpu/sh5/switchto.S b/arch/sh/kernel/cpu/sh5/switchto.S
new file mode 100644
index 000000000000..45b2d90eed7d
--- /dev/null
+++ b/arch/sh/kernel/cpu/sh5/switchto.S
@@ -0,0 +1,198 @@
1/*
2 * arch/sh64/kernel/switchto.S
3 *
4 * sh64 context switch
5 *
6 * Copyright (C) 2004 Richard Curnow
7 *
8 * This file is subject to the terms and conditions of the GNU General Public
9 * License. See the file "COPYING" in the main directory of this archive
10 * for more details.
11*/
12
13 .section .text..SHmedia32,"ax"
14 .little
15
16 .balign 32
17
18 .type sh64_switch_to,@function
19 .global sh64_switch_to
20 .global __sh64_switch_to_end
21sh64_switch_to:
22
23/* Incoming args
24 r2 - prev
25 r3 - &prev->thread
26 r4 - next
27 r5 - &next->thread
28
29 Outgoing results
30 r2 - last (=prev) : this just stays in r2 throughout
31
32 Want to create a full (struct pt_regs) on the stack to allow backtracing
33 functions to work. However, we only need to populate the callee-save
34 register slots in this structure; since we're a function our ancestors must
35 have themselves preserved all caller saved state in the stack. This saves
36 some wasted effort since we won't need to look at the values.
37
38 In particular, all caller-save registers are immediately available for
39 scratch use.
40
41*/
42
43#define FRAME_SIZE (76*8 + 8)
44
45 movi FRAME_SIZE, r0
46 sub.l r15, r0, r15
47 ! Do normal-style register save to support backtrace
48
49 st.l r15, 0, r18 ! save link reg
50 st.l r15, 4, r14 ! save fp
51 add.l r15, r63, r14 ! setup frame pointer
52
53 ! hopefully this looks normal to the backtrace now.
54
55 addi.l r15, 8, r1 ! base of pt_regs
56 addi.l r1, 24, r0 ! base of pt_regs.regs
57 addi.l r0, (63*8), r8 ! base of pt_regs.trregs
58
59 /* Note : to be fixed?
60 struct pt_regs is really designed for holding the state on entry
61 to an exception, i.e. pc,sr,regs etc. However, for the context
62 switch state, some of this is not required. But the unwinder takes
63 struct pt_regs * as an arg so we have to build this structure
64 to allow unwinding switched tasks in show_state() */
65
66 st.q r0, ( 9*8), r9
67 st.q r0, (10*8), r10
68 st.q r0, (11*8), r11
69 st.q r0, (12*8), r12
70 st.q r0, (13*8), r13
71 st.q r0, (14*8), r14 ! for unwind, want to look as though we took a trap at
72 ! the point where the process is left in suspended animation, i.e. current
73 ! fp here, not the saved one.
74 st.q r0, (16*8), r16
75
76 st.q r0, (24*8), r24
77 st.q r0, (25*8), r25
78 st.q r0, (26*8), r26
79 st.q r0, (27*8), r27
80 st.q r0, (28*8), r28
81 st.q r0, (29*8), r29
82 st.q r0, (30*8), r30
83 st.q r0, (31*8), r31
84 st.q r0, (32*8), r32
85 st.q r0, (33*8), r33
86 st.q r0, (34*8), r34
87 st.q r0, (35*8), r35
88
89 st.q r0, (44*8), r44
90 st.q r0, (45*8), r45
91 st.q r0, (46*8), r46
92 st.q r0, (47*8), r47
93 st.q r0, (48*8), r48
94 st.q r0, (49*8), r49
95 st.q r0, (50*8), r50
96 st.q r0, (51*8), r51
97 st.q r0, (52*8), r52
98 st.q r0, (53*8), r53
99 st.q r0, (54*8), r54
100 st.q r0, (55*8), r55
101 st.q r0, (56*8), r56
102 st.q r0, (57*8), r57
103 st.q r0, (58*8), r58
104 st.q r0, (59*8), r59
105
106 ! do this early as pta->gettr has no pipeline forwarding (=> 5 cycle latency)
107 ! Use a local label to avoid creating a symbol that will confuse the !
108 ! backtrace
109 pta .Lsave_pc, tr0
110
111 gettr tr5, r45
112 gettr tr6, r46
113 gettr tr7, r47
114 st.q r8, (5*8), r45
115 st.q r8, (6*8), r46
116 st.q r8, (7*8), r47
117
118 ! Now switch context
119 gettr tr0, r9
120 st.l r3, 0, r15 ! prev->thread.sp
121 st.l r3, 8, r1 ! prev->thread.kregs
122 st.l r3, 4, r9 ! prev->thread.pc
123 st.q r1, 0, r9 ! save prev->thread.pc into pt_regs->pc
124
125 ! Load PC for next task (init value or save_pc later)
126 ld.l r5, 4, r18 ! next->thread.pc
127 ! Switch stacks
128 ld.l r5, 0, r15 ! next->thread.sp
129 ptabs r18, tr0
130
131 ! Update current
132 ld.l r4, 4, r9 ! next->thread_info (2nd element of next task_struct)
133 putcon r9, kcr0 ! current = next->thread_info
134
135 ! go to save_pc for a reschedule, or the initial thread.pc for a new process
136 blink tr0, r63
137
138 ! Restore (when we come back to a previously saved task)
139.Lsave_pc:
140 addi.l r15, 32, r0 ! r0 = next's regs
141 addi.l r0, (63*8), r8 ! r8 = next's tr_regs
142
143 ld.q r8, (5*8), r45
144 ld.q r8, (6*8), r46
145 ld.q r8, (7*8), r47
146 ptabs r45, tr5
147 ptabs r46, tr6
148 ptabs r47, tr7
149
150 ld.q r0, ( 9*8), r9
151 ld.q r0, (10*8), r10
152 ld.q r0, (11*8), r11
153 ld.q r0, (12*8), r12
154 ld.q r0, (13*8), r13
155 ld.q r0, (14*8), r14
156 ld.q r0, (16*8), r16
157
158 ld.q r0, (24*8), r24
159 ld.q r0, (25*8), r25
160 ld.q r0, (26*8), r26
161 ld.q r0, (27*8), r27
162 ld.q r0, (28*8), r28
163 ld.q r0, (29*8), r29
164 ld.q r0, (30*8), r30
165 ld.q r0, (31*8), r31
166 ld.q r0, (32*8), r32
167 ld.q r0, (33*8), r33
168 ld.q r0, (34*8), r34
169 ld.q r0, (35*8), r35
170
171 ld.q r0, (44*8), r44
172 ld.q r0, (45*8), r45
173 ld.q r0, (46*8), r46
174 ld.q r0, (47*8), r47
175 ld.q r0, (48*8), r48
176 ld.q r0, (49*8), r49
177 ld.q r0, (50*8), r50
178 ld.q r0, (51*8), r51
179 ld.q r0, (52*8), r52
180 ld.q r0, (53*8), r53
181 ld.q r0, (54*8), r54
182 ld.q r0, (55*8), r55
183 ld.q r0, (56*8), r56
184 ld.q r0, (57*8), r57
185 ld.q r0, (58*8), r58
186 ld.q r0, (59*8), r59
187
188 ! epilogue
189 ld.l r15, 0, r18
190 ld.l r15, 4, r14
191 ptabs r18, tr0
192 movi FRAME_SIZE, r0
193 add r15, r0, r15
194 blink tr0, r63
195__sh64_switch_to_end:
196.LFE1:
197 .size sh64_switch_to,.LFE1-sh64_switch_to
198
diff --git a/arch/sh/kernel/cpu/sh5/unwind.c b/arch/sh/kernel/cpu/sh5/unwind.c
new file mode 100644
index 000000000000..1214c78e3584
--- /dev/null
+++ b/arch/sh/kernel/cpu/sh5/unwind.c
@@ -0,0 +1,326 @@
1/*
2 * arch/sh64/kernel/unwind.c
3 *
4 * Copyright (C) 2004 Paul Mundt
5 * Copyright (C) 2004 Richard Curnow
6 *
7 * This file is subject to the terms and conditions of the GNU General Public
8 * License. See the file "COPYING" in the main directory of this archive
9 * for more details.
10 */
11#include <linux/kallsyms.h>
12#include <linux/kernel.h>
13#include <linux/types.h>
14#include <linux/errno.h>
15#include <asm/page.h>
16#include <asm/ptrace.h>
17#include <asm/processor.h>
18#include <asm/io.h>
19
20static u8 regcache[63];
21
22/*
23 * Finding the previous stack frame isn't horribly straightforward as it is
24 * on some other platforms. In the sh64 case, we don't have "linked" stack
25 * frames, so we need to do a bit of work to determine the previous frame,
26 * and in turn, the previous r14/r18 pair.
27 *
28 * There are generally a few cases which determine where we can find out
29 * the r14/r18 values. In the general case, this can be determined by poking
30 * around the prologue of the symbol PC is in (note that we absolutely must
31 * have frame pointer support as well as the kernel symbol table mapped,
32 * otherwise we can't even get this far).
33 *
34 * In other cases, such as the interrupt/exception path, we can poke around
35 * the sp/fp.
36 *
37 * Notably, this entire approach is somewhat error prone, and in the event
38 * that the previous frame cannot be determined, that's all we can do.
39 * Either way, this still leaves us with a more correct backtrace then what
40 * we would be able to come up with by walking the stack (which is garbage
41 * for anything beyond the first frame).
42 * -- PFM.
43 */
44static int lookup_prev_stack_frame(unsigned long fp, unsigned long pc,
45 unsigned long *pprev_fp, unsigned long *pprev_pc,
46 struct pt_regs *regs)
47{
48 const char *sym;
49 char namebuf[128];
50 unsigned long offset;
51 unsigned long prologue = 0;
52 unsigned long fp_displacement = 0;
53 unsigned long fp_prev = 0;
54 unsigned long offset_r14 = 0, offset_r18 = 0;
55 int i, found_prologue_end = 0;
56
57 sym = kallsyms_lookup(pc, NULL, &offset, NULL, namebuf);
58 if (!sym)
59 return -EINVAL;
60
61 prologue = pc - offset;
62 if (!prologue)
63 return -EINVAL;
64
65 /* Validate fp, to avoid risk of dereferencing a bad pointer later.
66 Assume 128Mb since that's the amount of RAM on a Cayman. Modify
67 when there is an SH-5 board with more. */
68 if ((fp < (unsigned long) phys_to_virt(__MEMORY_START)) ||
69 (fp >= (unsigned long)(phys_to_virt(__MEMORY_START)) + 128*1024*1024) ||
70 ((fp & 7) != 0)) {
71 return -EINVAL;
72 }
73
74 /*
75 * Depth to walk, depth is completely arbitrary.
76 */
77 for (i = 0; i < 100; i++, prologue += sizeof(unsigned long)) {
78 unsigned long op;
79 u8 major, minor;
80 u8 src, dest, disp;
81
82 op = *(unsigned long *)prologue;
83
84 major = (op >> 26) & 0x3f;
85 src = (op >> 20) & 0x3f;
86 minor = (op >> 16) & 0xf;
87 disp = (op >> 10) & 0x3f;
88 dest = (op >> 4) & 0x3f;
89
90 /*
91 * Stack frame creation happens in a number of ways.. in the
92 * general case when the stack frame is less than 511 bytes,
93 * it's generally created by an addi or addi.l:
94 *
95 * addi/addi.l r15, -FRAME_SIZE, r15
96 *
97 * in the event that the frame size is bigger than this, it's
98 * typically created using a movi/sub pair as follows:
99 *
100 * movi FRAME_SIZE, rX
101 * sub r15, rX, r15
102 */
103
104 switch (major) {
105 case (0x00 >> 2):
106 switch (minor) {
107 case 0x8: /* add.l */
108 case 0x9: /* add */
109 /* Look for r15, r63, r14 */
110 if (src == 15 && disp == 63 && dest == 14)
111 found_prologue_end = 1;
112
113 break;
114 case 0xa: /* sub.l */
115 case 0xb: /* sub */
116 if (src != 15 || dest != 15)
117 continue;
118
119 fp_displacement -= regcache[disp];
120 fp_prev = fp - fp_displacement;
121 break;
122 }
123 break;
124 case (0xa8 >> 2): /* st.l */
125 if (src != 15)
126 continue;
127
128 switch (dest) {
129 case 14:
130 if (offset_r14 || fp_displacement == 0)
131 continue;
132
133 offset_r14 = (u64)(((((s64)op >> 10) & 0x3ff) << 54) >> 54);
134 offset_r14 *= sizeof(unsigned long);
135 offset_r14 += fp_displacement;
136 break;
137 case 18:
138 if (offset_r18 || fp_displacement == 0)
139 continue;
140
141 offset_r18 = (u64)(((((s64)op >> 10) & 0x3ff) << 54) >> 54);
142 offset_r18 *= sizeof(unsigned long);
143 offset_r18 += fp_displacement;
144 break;
145 }
146
147 break;
148 case (0xcc >> 2): /* movi */
149 if (dest >= 63) {
150 printk(KERN_NOTICE "%s: Invalid dest reg %d "
151 "specified in movi handler. Failed "
152 "opcode was 0x%lx: ", __FUNCTION__,
153 dest, op);
154
155 continue;
156 }
157
158 /* Sign extend */
159 regcache[dest] =
160 ((((s64)(u64)op >> 10) & 0xffff) << 54) >> 54;
161 break;
162 case (0xd0 >> 2): /* addi */
163 case (0xd4 >> 2): /* addi.l */
164 /* Look for r15, -FRAME_SIZE, r15 */
165 if (src != 15 || dest != 15)
166 continue;
167
168 /* Sign extended frame size.. */
169 fp_displacement +=
170 (u64)(((((s64)op >> 10) & 0x3ff) << 54) >> 54);
171 fp_prev = fp - fp_displacement;
172 break;
173 }
174
175 if (found_prologue_end && offset_r14 && (offset_r18 || *pprev_pc) && fp_prev)
176 break;
177 }
178
179 if (offset_r14 == 0 || fp_prev == 0) {
180 if (!offset_r14)
181 pr_debug("Unable to find r14 offset\n");
182 if (!fp_prev)
183 pr_debug("Unable to find previous fp\n");
184
185 return -EINVAL;
186 }
187
188 /* For innermost leaf function, there might not be a offset_r18 */
189 if (!*pprev_pc && (offset_r18 == 0))
190 return -EINVAL;
191
192 *pprev_fp = *(unsigned long *)(fp_prev + offset_r14);
193
194 if (offset_r18)
195 *pprev_pc = *(unsigned long *)(fp_prev + offset_r18);
196
197 *pprev_pc &= ~1;
198
199 return 0;
200}
201
202/* Don't put this on the stack since we'll want to call sh64_unwind
203 * when we're close to underflowing the stack anyway. */
204static struct pt_regs here_regs;
205
206extern const char syscall_ret;
207extern const char ret_from_syscall;
208extern const char ret_from_exception;
209extern const char ret_from_irq;
210
211static void sh64_unwind_inner(struct pt_regs *regs);
212
213static void unwind_nested (unsigned long pc, unsigned long fp)
214{
215 if ((fp >= __MEMORY_START) &&
216 ((fp & 7) == 0)) {
217 sh64_unwind_inner((struct pt_regs *) fp);
218 }
219}
220
221static void sh64_unwind_inner(struct pt_regs *regs)
222{
223 unsigned long pc, fp;
224 int ofs = 0;
225 int first_pass;
226
227 pc = regs->pc & ~1;
228 fp = regs->regs[14];
229
230 first_pass = 1;
231 for (;;) {
232 int cond;
233 unsigned long next_fp, next_pc;
234
235 if (pc == ((unsigned long) &syscall_ret & ~1)) {
236 printk("SYSCALL\n");
237 unwind_nested(pc,fp);
238 return;
239 }
240
241 if (pc == ((unsigned long) &ret_from_syscall & ~1)) {
242 printk("SYSCALL (PREEMPTED)\n");
243 unwind_nested(pc,fp);
244 return;
245 }
246
247 /* In this case, the PC is discovered by lookup_prev_stack_frame but
248 it has 4 taken off it to look like the 'caller' */
249 if (pc == ((unsigned long) &ret_from_exception & ~1)) {
250 printk("EXCEPTION\n");
251 unwind_nested(pc,fp);
252 return;
253 }
254
255 if (pc == ((unsigned long) &ret_from_irq & ~1)) {
256 printk("IRQ\n");
257 unwind_nested(pc,fp);
258 return;
259 }
260
261 cond = ((pc >= __MEMORY_START) && (fp >= __MEMORY_START) &&
262 ((pc & 3) == 0) && ((fp & 7) == 0));
263
264 pc -= ofs;
265
266 printk("[<%08lx>] ", pc);
267 print_symbol("%s\n", pc);
268
269 if (first_pass) {
270 /* If the innermost frame is a leaf function, it's
271 * possible that r18 is never saved out to the stack.
272 */
273 next_pc = regs->regs[18];
274 } else {
275 next_pc = 0;
276 }
277
278 if (lookup_prev_stack_frame(fp, pc, &next_fp, &next_pc, regs) == 0) {
279 ofs = sizeof(unsigned long);
280 pc = next_pc & ~1;
281 fp = next_fp;
282 } else {
283 printk("Unable to lookup previous stack frame\n");
284 break;
285 }
286 first_pass = 0;
287 }
288
289 printk("\n");
290
291}
292
293void sh64_unwind(struct pt_regs *regs)
294{
295 if (!regs) {
296 /*
297 * Fetch current regs if we have no other saved state to back
298 * trace from.
299 */
300 regs = &here_regs;
301
302 __asm__ __volatile__ ("ori r14, 0, %0" : "=r" (regs->regs[14]));
303 __asm__ __volatile__ ("ori r15, 0, %0" : "=r" (regs->regs[15]));
304 __asm__ __volatile__ ("ori r18, 0, %0" : "=r" (regs->regs[18]));
305
306 __asm__ __volatile__ ("gettr tr0, %0" : "=r" (regs->tregs[0]));
307 __asm__ __volatile__ ("gettr tr1, %0" : "=r" (regs->tregs[1]));
308 __asm__ __volatile__ ("gettr tr2, %0" : "=r" (regs->tregs[2]));
309 __asm__ __volatile__ ("gettr tr3, %0" : "=r" (regs->tregs[3]));
310 __asm__ __volatile__ ("gettr tr4, %0" : "=r" (regs->tregs[4]));
311 __asm__ __volatile__ ("gettr tr5, %0" : "=r" (regs->tregs[5]));
312 __asm__ __volatile__ ("gettr tr6, %0" : "=r" (regs->tregs[6]));
313 __asm__ __volatile__ ("gettr tr7, %0" : "=r" (regs->tregs[7]));
314
315 __asm__ __volatile__ (
316 "pta 0f, tr0\n\t"
317 "blink tr0, %0\n\t"
318 "0: nop"
319 : "=r" (regs->pc)
320 );
321 }
322
323 printk("\nCall Trace:\n");
324 sh64_unwind_inner(regs);
325}
326
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