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authorJosh Poimboeuf <jpoimboe@redhat.com>2016-09-15 04:07:41 +0200
committerIngo Molnar <mingo@kernel.org>2016-09-15 08:13:14 +0200
commit9c00390757fd9f5851f7973b2f0e1e41550bb3b8 (patch)
tree244faccad861301afb9701f5f222b3c66e610a97 /arch/x86/kernel/dumpstack_64.c
parentx86/dumpstack: Allow preemption in show_stack_log_lvl() and dump_trace() (diff)
downloadlinux-9c00390757fd9f5851f7973b2f0e1e41550bb3b8.tar.xz
linux-9c00390757fd9f5851f7973b2f0e1e41550bb3b8.zip
x86/dumpstack: Simplify in_exception_stack()
in_exception_stack() does some bad, bad things just so the unwinder can print different values for different areas of the debug exception stack. There's no need to clarify where exactly on the stack it is. Just print "#DB" and be done with it. Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Andy Lutomirski <luto@kernel.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Byungchul Park <byungchul.park@lge.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Kees Cook <keescook@chromium.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Nilay Vaish <nilayvaish@gmail.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/e91cb410169dd576678dd427c35efb716fd0cee1.1473905218.git.jpoimboe@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/x86/kernel/dumpstack_64.c')
-rw-r--r--arch/x86/kernel/dumpstack_64.c89
1 files changed, 26 insertions, 63 deletions
diff --git a/arch/x86/kernel/dumpstack_64.c b/arch/x86/kernel/dumpstack_64.c
index 07373bec76f1..904fb46d7d65 100644
--- a/arch/x86/kernel/dumpstack_64.c
+++ b/arch/x86/kernel/dumpstack_64.c
@@ -16,83 +16,46 @@
#include <asm/stacktrace.h>
+static char *exception_stack_names[N_EXCEPTION_STACKS] = {
+ [ DOUBLEFAULT_STACK-1 ] = "#DF",
+ [ NMI_STACK-1 ] = "NMI",
+ [ DEBUG_STACK-1 ] = "#DB",
+ [ MCE_STACK-1 ] = "#MC",
+};
-#define N_EXCEPTION_STACKS_END \
- (N_EXCEPTION_STACKS + DEBUG_STKSZ/EXCEPTION_STKSZ - 2)
-
-static char x86_stack_ids[][8] = {
- [ DEBUG_STACK-1 ] = "#DB",
- [ NMI_STACK-1 ] = "NMI",
- [ DOUBLEFAULT_STACK-1 ] = "#DF",
- [ MCE_STACK-1 ] = "#MC",
-#if DEBUG_STKSZ > EXCEPTION_STKSZ
- [ N_EXCEPTION_STACKS ...
- N_EXCEPTION_STACKS_END ] = "#DB[?]"
-#endif
+static unsigned long exception_stack_sizes[N_EXCEPTION_STACKS] = {
+ [0 ... N_EXCEPTION_STACKS - 1] = EXCEPTION_STKSZ,
+ [DEBUG_STACK - 1] = DEBUG_STKSZ
};
static unsigned long *in_exception_stack(unsigned long stack, unsigned *usedp,
char **idp)
{
+ unsigned long begin, end;
unsigned k;
- /*
- * Iterate over all exception stacks, and figure out whether
- * 'stack' is in one of them:
- */
+ BUILD_BUG_ON(N_EXCEPTION_STACKS != 4);
+
for (k = 0; k < N_EXCEPTION_STACKS; k++) {
- unsigned long end = raw_cpu_ptr(&orig_ist)->ist[k];
- /*
- * Is 'stack' above this exception frame's end?
- * If yes then skip to the next frame.
- */
- if (stack >= end)
+ end = raw_cpu_ptr(&orig_ist)->ist[k];
+ begin = end - exception_stack_sizes[k];
+
+ if (stack < begin || 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 = x86_stack_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:
+ * 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 and return NULL:
*/
-#if DEBUG_STKSZ > EXCEPTION_STKSZ
- if (k == DEBUG_STACK - 1 && stack >= end - DEBUG_STKSZ) {
- unsigned j = N_EXCEPTION_STACKS - 1;
+ if (*usedp & (1U << k))
+ break;
+ *usedp |= 1U << k;
- /*
- * 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;
- x86_stack_ids[j][4] = '1' +
- (j - N_EXCEPTION_STACKS);
- } while (stack < end - EXCEPTION_STKSZ);
- if (*usedp & (1U << j))
- break;
- *usedp |= 1U << j;
- *idp = x86_stack_ids[j];
- return (unsigned long *)end;
- }
-#endif
+ *idp = exception_stack_names[k];
+ return (unsigned long *)end;
}
+
return NULL;
}