[PATCH] lockdep: x86_64 document stack frame internals
Document stack frame nesting internals some more. Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Arjan van de Ven <arjan@linux.intel.com> Cc: Andi Kleen <ak@muc.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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arch/x86_64/kernel
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@ -152,10 +152,22 @@ static unsigned long *in_exception_stack(unsigned cpu, unsigned long stack,
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};
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unsigned k;
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/*
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* Iterate over all exception stacks, and figure out whether
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* 'stack' is in one of them:
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*/
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for (k = 0; k < N_EXCEPTION_STACKS; k++) {
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unsigned long end;
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/*
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* set 'end' to the end of the exception stack.
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*/
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switch (k + 1) {
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/*
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* TODO: this block is not needed i think, because
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* setup64.c:cpu_init() sets up t->ist[DEBUG_STACK]
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* properly too.
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*/
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#if DEBUG_STKSZ > EXCEPTION_STKSZ
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case DEBUG_STACK:
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end = cpu_pda(cpu)->debugstack + DEBUG_STKSZ;
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@ -165,19 +177,43 @@ static unsigned long *in_exception_stack(unsigned cpu, unsigned long stack,
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end = per_cpu(init_tss, cpu).ist[k];
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break;
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}
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/*
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* Is 'stack' above this exception frame's end?
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* If yes then skip to the next frame.
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*/
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if (stack >= end)
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continue;
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/*
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* Is 'stack' above this exception frame's start address?
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* If yes then we found the right frame.
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*/
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if (stack >= end - EXCEPTION_STKSZ) {
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/*
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* Make sure we only iterate through an exception
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* stack once. If it comes up for the second time
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* then there's something wrong going on - just
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* break out and return NULL:
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*/
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if (*usedp & (1U << k))
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break;
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*usedp |= 1U << k;
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*idp = ids[k];
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return (unsigned long *)end;
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}
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/*
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* If this is a debug stack, and if it has a larger size than
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* the usual exception stacks, then 'stack' might still
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* be within the lower portion of the debug stack:
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*/
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#if DEBUG_STKSZ > EXCEPTION_STKSZ
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if (k == DEBUG_STACK - 1 && stack >= end - DEBUG_STKSZ) {
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unsigned j = N_EXCEPTION_STACKS - 1;
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/*
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* Black magic. A large debug stack is composed of
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* multiple exception stack entries, which we
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* iterate through now. Dont look:
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*/
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do {
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++j;
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end -= EXCEPTION_STKSZ;
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@ -247,6 +283,11 @@ void show_trace(struct task_struct *tsk, struct pt_regs *regs, unsigned long * s
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}
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}
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/*
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* Print function call entries within a stack. 'cond' is the
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* "end of stackframe" condition, that the 'stack++'
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* iteration will eventually trigger.
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*/
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#define HANDLE_STACK(cond) \
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do while (cond) { \
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unsigned long addr = *stack++; \
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@ -263,7 +304,12 @@ void show_trace(struct task_struct *tsk, struct pt_regs *regs, unsigned long * s
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} \
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} while (0)
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for( ; ; ) {
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/*
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* Print function call entries in all stacks, starting at the
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* current stack address. If the stacks consist of nested
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* exceptions
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*/
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for ( ; ; ) {
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const char *id;
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unsigned long *estack_end;
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estack_end = in_exception_stack(cpu, (unsigned long)stack,
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@ -273,6 +319,11 @@ void show_trace(struct task_struct *tsk, struct pt_regs *regs, unsigned long * s
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printk(" <%s>", id);
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HANDLE_STACK (stack < estack_end);
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printk(" <EOE>");
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/*
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* We link to the next stack via the
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* second-to-last pointer (index -2 to end) in the
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* exception stack:
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*/
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stack = (unsigned long *) estack_end[-2];
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continue;
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}
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@ -284,6 +335,11 @@ void show_trace(struct task_struct *tsk, struct pt_regs *regs, unsigned long * s
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if (stack >= irqstack && stack < irqstack_end) {
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printk(" <IRQ>");
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HANDLE_STACK (stack < irqstack_end);
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/*
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* We link to the next stack (which would be
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* the process stack normally) the last
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* pointer (index -1 to end) in the IRQ stack:
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*/
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stack = (unsigned long *) (irqstack_end[-1]);
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irqstack_end = NULL;
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printk(" <EOI>");
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@ -293,6 +349,9 @@ void show_trace(struct task_struct *tsk, struct pt_regs *regs, unsigned long * s
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break;
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}
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/*
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* This prints the process stack:
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*/
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HANDLE_STACK (((long) stack & (THREAD_SIZE-1)) != 0);
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#undef HANDLE_STACK
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