aboutsummaryrefslogtreecommitdiffstats
path: root/arch/x86_64
diff options
context:
space:
mode:
Diffstat (limited to 'arch/x86_64')
-rw-r--r--arch/x86_64/kernel/traps.c61
1 files changed, 60 insertions, 1 deletions
diff --git a/arch/x86_64/kernel/traps.c b/arch/x86_64/kernel/traps.c
index 02dc155da56f..79d05c482072 100644
--- a/arch/x86_64/kernel/traps.c
+++ b/arch/x86_64/kernel/traps.c
@@ -152,10 +152,22 @@ static unsigned long *in_exception_stack(unsigned cpu, unsigned long stack,
152 }; 152 };
153 unsigned k; 153 unsigned k;
154 154
155 /*
156 * Iterate over all exception stacks, and figure out whether
157 * 'stack' is in one of them:
158 */
155 for (k = 0; k < N_EXCEPTION_STACKS; k++) { 159 for (k = 0; k < N_EXCEPTION_STACKS; k++) {
156 unsigned long end; 160 unsigned long end;
157 161
162 /*
163 * set 'end' to the end of the exception stack.
164 */
158 switch (k + 1) { 165 switch (k + 1) {
166 /*
167 * TODO: this block is not needed i think, because
168 * setup64.c:cpu_init() sets up t->ist[DEBUG_STACK]
169 * properly too.
170 */
159#if DEBUG_STKSZ > EXCEPTION_STKSZ 171#if DEBUG_STKSZ > EXCEPTION_STKSZ
160 case DEBUG_STACK: 172 case DEBUG_STACK:
161 end = cpu_pda(cpu)->debugstack + DEBUG_STKSZ; 173 end = cpu_pda(cpu)->debugstack + DEBUG_STKSZ;
@@ -165,19 +177,43 @@ static unsigned long *in_exception_stack(unsigned cpu, unsigned long stack,
165 end = per_cpu(init_tss, cpu).ist[k]; 177 end = per_cpu(init_tss, cpu).ist[k];
166 break; 178 break;
167 } 179 }
180 /*
181 * Is 'stack' above this exception frame's end?
182 * If yes then skip to the next frame.
183 */
168 if (stack >= end) 184 if (stack >= end)
169 continue; 185 continue;
186 /*
187 * Is 'stack' above this exception frame's start address?
188 * If yes then we found the right frame.
189 */
170 if (stack >= end - EXCEPTION_STKSZ) { 190 if (stack >= end - EXCEPTION_STKSZ) {
191 /*
192 * Make sure we only iterate through an exception
193 * stack once. If it comes up for the second time
194 * then there's something wrong going on - just
195 * break out and return NULL:
196 */
171 if (*usedp & (1U << k)) 197 if (*usedp & (1U << k))
172 break; 198 break;
173 *usedp |= 1U << k; 199 *usedp |= 1U << k;
174 *idp = ids[k]; 200 *idp = ids[k];
175 return (unsigned long *)end; 201 return (unsigned long *)end;
176 } 202 }
203 /*
204 * If this is a debug stack, and if it has a larger size than
205 * the usual exception stacks, then 'stack' might still
206 * be within the lower portion of the debug stack:
207 */
177#if DEBUG_STKSZ > EXCEPTION_STKSZ 208#if DEBUG_STKSZ > EXCEPTION_STKSZ
178 if (k == DEBUG_STACK - 1 && stack >= end - DEBUG_STKSZ) { 209 if (k == DEBUG_STACK - 1 && stack >= end - DEBUG_STKSZ) {
179 unsigned j = N_EXCEPTION_STACKS - 1; 210 unsigned j = N_EXCEPTION_STACKS - 1;
180 211
212 /*
213 * Black magic. A large debug stack is composed of
214 * multiple exception stack entries, which we
215 * iterate through now. Dont look:
216 */
181 do { 217 do {
182 ++j; 218 ++j;
183 end -= EXCEPTION_STKSZ; 219 end -= EXCEPTION_STKSZ;
@@ -247,6 +283,11 @@ void show_trace(struct task_struct *tsk, struct pt_regs *regs, unsigned long * s
247 } 283 }
248 } 284 }
249 285
286 /*
287 * Print function call entries within a stack. 'cond' is the
288 * "end of stackframe" condition, that the 'stack++'
289 * iteration will eventually trigger.
290 */
250#define HANDLE_STACK(cond) \ 291#define HANDLE_STACK(cond) \
251 do while (cond) { \ 292 do while (cond) { \
252 unsigned long addr = *stack++; \ 293 unsigned long addr = *stack++; \
@@ -263,7 +304,12 @@ void show_trace(struct task_struct *tsk, struct pt_regs *regs, unsigned long * s
263 } \ 304 } \
264 } while (0) 305 } while (0)
265 306
266 for( ; ; ) { 307 /*
308 * Print function call entries in all stacks, starting at the
309 * current stack address. If the stacks consist of nested
310 * exceptions
311 */
312 for ( ; ; ) {
267 const char *id; 313 const char *id;
268 unsigned long *estack_end; 314 unsigned long *estack_end;
269 estack_end = in_exception_stack(cpu, (unsigned long)stack, 315 estack_end = in_exception_stack(cpu, (unsigned long)stack,
@@ -273,6 +319,11 @@ void show_trace(struct task_struct *tsk, struct pt_regs *regs, unsigned long * s
273 printk(" <%s>", id); 319 printk(" <%s>", id);
274 HANDLE_STACK (stack < estack_end); 320 HANDLE_STACK (stack < estack_end);
275 printk(" <EOE>"); 321 printk(" <EOE>");
322 /*
323 * We link to the next stack via the
324 * second-to-last pointer (index -2 to end) in the
325 * exception stack:
326 */
276 stack = (unsigned long *) estack_end[-2]; 327 stack = (unsigned long *) estack_end[-2];
277 continue; 328 continue;
278 } 329 }
@@ -284,6 +335,11 @@ void show_trace(struct task_struct *tsk, struct pt_regs *regs, unsigned long * s
284 if (stack >= irqstack && stack < irqstack_end) { 335 if (stack >= irqstack && stack < irqstack_end) {
285 printk(" <IRQ>"); 336 printk(" <IRQ>");
286 HANDLE_STACK (stack < irqstack_end); 337 HANDLE_STACK (stack < irqstack_end);
338 /*
339 * We link to the next stack (which would be
340 * the process stack normally) the last
341 * pointer (index -1 to end) in the IRQ stack:
342 */
287 stack = (unsigned long *) (irqstack_end[-1]); 343 stack = (unsigned long *) (irqstack_end[-1]);
288 irqstack_end = NULL; 344 irqstack_end = NULL;
289 printk(" <EOI>"); 345 printk(" <EOI>");
@@ -293,6 +349,9 @@ void show_trace(struct task_struct *tsk, struct pt_regs *regs, unsigned long * s
293 break; 349 break;
294 } 350 }
295 351
352 /*
353 * This prints the process stack:
354 */
296 HANDLE_STACK (((long) stack & (THREAD_SIZE-1)) != 0); 355 HANDLE_STACK (((long) stack & (THREAD_SIZE-1)) != 0);
297#undef HANDLE_STACK 356#undef HANDLE_STACK
298 357