Commit c9ca1ba5 authored by Ingo Molnar's avatar Ingo Molnar Committed by Linus Torvalds

[PATCH] lockdep: x86_64 document stack frame internals

Document stack frame nesting internals some more.
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
Signed-off-by: default avatarArjan van de Ven <arjan@linux.intel.com>
Cc: Andi Kleen <ak@muc.de>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 3ac94932
......@@ -152,10 +152,22 @@ static unsigned long *in_exception_stack(unsigned cpu, unsigned long stack,
};
unsigned k;
/*
* Iterate over all exception stacks, and figure out whether
* 'stack' is in one of them:
*/
for (k = 0; k < N_EXCEPTION_STACKS; k++) {
unsigned long end;
/*
* set 'end' to the end of the exception stack.
*/
switch (k + 1) {
/*
* TODO: this block is not needed i think, because
* setup64.c:cpu_init() sets up t->ist[DEBUG_STACK]
* properly too.
*/
#if DEBUG_STKSZ > EXCEPTION_STKSZ
case DEBUG_STACK:
end = cpu_pda(cpu)->debugstack + DEBUG_STKSZ;
......@@ -165,19 +177,43 @@ static unsigned long *in_exception_stack(unsigned cpu, unsigned long stack,
end = per_cpu(init_tss, cpu).ist[k];
break;
}
/*
* Is 'stack' above this exception frame's end?
* If yes then skip to the next frame.
*/
if (stack >= end)
continue;
/*
* Is 'stack' above this exception frame's start address?
* If yes then we found the right frame.
*/
if (stack >= end - EXCEPTION_STKSZ) {
/*
* Make sure we only iterate through an exception
* stack once. If it comes up for the second time
* then there's something wrong going on - just
* break out and return NULL:
*/
if (*usedp & (1U << k))
break;
*usedp |= 1U << k;
*idp = ids[k];
return (unsigned long *)end;
}
/*
* If this is a debug stack, and if it has a larger size than
* the usual exception stacks, then 'stack' might still
* be within the lower portion of the debug stack:
*/
#if DEBUG_STKSZ > EXCEPTION_STKSZ
if (k == DEBUG_STACK - 1 && stack >= end - DEBUG_STKSZ) {
unsigned j = N_EXCEPTION_STACKS - 1;
/*
* Black magic. A large debug stack is composed of
* multiple exception stack entries, which we
* iterate through now. Dont look:
*/
do {
++j;
end -= EXCEPTION_STKSZ;
......@@ -247,6 +283,11 @@ void show_trace(struct task_struct *tsk, struct pt_regs *regs, unsigned long * s
}
}
/*
* Print function call entries within a stack. 'cond' is the
* "end of stackframe" condition, that the 'stack++'
* iteration will eventually trigger.
*/
#define HANDLE_STACK(cond) \
do while (cond) { \
unsigned long addr = *stack++; \
......@@ -263,7 +304,12 @@ void show_trace(struct task_struct *tsk, struct pt_regs *regs, unsigned long * s
} \
} while (0)
for( ; ; ) {
/*
* Print function call entries in all stacks, starting at the
* current stack address. If the stacks consist of nested
* exceptions
*/
for ( ; ; ) {
const char *id;
unsigned long *estack_end;
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
printk(" <%s>", id);
HANDLE_STACK (stack < estack_end);
printk(" <EOE>");
/*
* We link to the next stack via the
* second-to-last pointer (index -2 to end) in the
* exception stack:
*/
stack = (unsigned long *) estack_end[-2];
continue;
}
......@@ -284,6 +335,11 @@ void show_trace(struct task_struct *tsk, struct pt_regs *regs, unsigned long * s
if (stack >= irqstack && stack < irqstack_end) {
printk(" <IRQ>");
HANDLE_STACK (stack < irqstack_end);
/*
* We link to the next stack (which would be
* the process stack normally) the last
* pointer (index -1 to end) in the IRQ stack:
*/
stack = (unsigned long *) (irqstack_end[-1]);
irqstack_end = NULL;
printk(" <EOI>");
......@@ -293,6 +349,9 @@ void show_trace(struct task_struct *tsk, struct pt_regs *regs, unsigned long * s
break;
}
/*
* This prints the process stack:
*/
HANDLE_STACK (((long) stack & (THREAD_SIZE-1)) != 0);
#undef HANDLE_STACK
......
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