X-Git-Url: http://git.cascardo.info/?p=cascardo%2Flinux.git;a=blobdiff_plain;f=arch%2Fx86%2Fmm%2Ffault.c;h=4dc13340653eb96d1e550b1a10b4635babba79b4;hp=b88d8acb3ab587e3651cf030fc1d410b9f31f1ac;hb=93c26d7dc02380fe11e57ff0d152368743762169;hpb=6679dac513fd612f34d3a3d99d7b84ed6d5eb5cc

diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c
index b88d8acb3ab5..4dc13340653e 100644
--- a/arch/x86/mm/fault.c
+++ b/arch/x86/mm/fault.c
@@ -5,7 +5,7 @@
  */
 #include <linux/sched.h>		/* test_thread_flag(), ...	*/
 #include <linux/kdebug.h>		/* oops_begin/end, ...		*/
-#include <linux/module.h>		/* search_exception_table	*/
+#include <linux/extable.h>		/* search_exception_table	*/
 #include <linux/bootmem.h>		/* max_low_pfn			*/
 #include <linux/kprobes.h>		/* NOKPROBE_SYMBOL, ...		*/
 #include <linux/mmiotrace.h>		/* kmmio_handler, ...		*/
@@ -753,6 +753,38 @@ no_context(struct pt_regs *regs, unsigned long error_code,
 		return;
 	}
 
+#ifdef CONFIG_VMAP_STACK
+	/*
+	 * Stack overflow?  During boot, we can fault near the initial
+	 * stack in the direct map, but that's not an overflow -- check
+	 * that we're in vmalloc space to avoid this.
+	 */
+	if (is_vmalloc_addr((void *)address) &&
+	    (((unsigned long)tsk->stack - 1 - address < PAGE_SIZE) ||
+	     address - ((unsigned long)tsk->stack + THREAD_SIZE) < PAGE_SIZE)) {
+		register void *__sp asm("rsp");
+		unsigned long stack = this_cpu_read(orig_ist.ist[DOUBLEFAULT_STACK]) - sizeof(void *);
+		/*
+		 * We're likely to be running with very little stack space
+		 * left.  It's plausible that we'd hit this condition but
+		 * double-fault even before we get this far, in which case
+		 * we're fine: the double-fault handler will deal with it.
+		 *
+		 * We don't want to make it all the way into the oops code
+		 * and then double-fault, though, because we're likely to
+		 * break the console driver and lose most of the stack dump.
+		 */
+		asm volatile ("movq %[stack], %%rsp\n\t"
+			      "call handle_stack_overflow\n\t"
+			      "1: jmp 1b"
+			      : "+r" (__sp)
+			      : "D" ("kernel stack overflow (page fault)"),
+				"S" (regs), "d" (address),
+				[stack] "rm" (stack));
+		unreachable();
+	}
+#endif
+
 	/*
 	 * 32-bit:
 	 *