x86/traps: Enable all exception handler callbacks early

[cascardo/linux.git] / arch / x86 / mm / extable.c

diff --git a/arch/x86/mm/extable.c b/arch/x86/mm/extable.c
index 9dd7e4b..061a237 100644 (file)
--- a/arch/x86/mm/extable.c
+++ b/arch/x86/mm/extable.c
@@ -1,16 +1,10 @@
 #include <linux/module.h>
-#include <linux/spinlock.h>
-#include <linux/sort.h>
 #include <asm/uaccess.h>
+#include <asm/traps.h>
 
 typedef bool (*ex_handler_t)(const struct exception_table_entry *,
                            struct pt_regs *, int);
 
-static inline unsigned long
-ex_insn_addr(const struct exception_table_entry *x)
-{
-       return (unsigned long)&x->insn + x->insn;
-}
 static inline unsigned long
 ex_fixup_addr(const struct exception_table_entry *x)
 {
@@ -89,125 +83,32 @@ int fixup_exception(struct pt_regs *regs, int trapnr)
        return handler(e, regs, trapnr);
 }
 
+extern unsigned int early_recursion_flag;
+
 /* Restricted version used during very early boot */
-int __init early_fixup_exception(unsigned long *ip)
+void __init early_fixup_exception(struct pt_regs *regs, int trapnr)
 {
-       const struct exception_table_entry *e;
-       unsigned long new_ip;
-       ex_handler_t handler;
-
-       e = search_exception_tables(*ip);
-       if (!e)
-               return 0;
-
-       new_ip  = ex_fixup_addr(e);
-       handler = ex_fixup_handler(e);
-
-       /* special handling not supported during early boot */
-       if (handler != ex_handler_default)
-               return 0;
+       /* Ignore early NMIs. */
+       if (trapnr == X86_TRAP_NMI)
+               return;
 
-       *ip = new_ip;
-       return 1;
-}
+       if (early_recursion_flag > 2)
+               goto halt_loop;
 
-/*
- * Search one exception table for an entry corresponding to the
- * given instruction address, and return the address of the entry,
- * or NULL if none is found.
- * We use a binary search, and thus we assume that the table is
- * already sorted.
- */
-const struct exception_table_entry *
-search_extable(const struct exception_table_entry *first,
-              const struct exception_table_entry *last,
-              unsigned long value)
-{
-       while (first <= last) {
-               const struct exception_table_entry *mid;
-               unsigned long addr;
-
-               mid = ((last - first) >> 1) + first;
-               addr = ex_insn_addr(mid);
-               if (addr < value)
-                       first = mid + 1;
-               else if (addr > value)
-                       last = mid - 1;
-               else
-                       return mid;
-        }
-        return NULL;
-}
+       if (regs->cs != __KERNEL_CS)
+               goto fail;
 
-/*
- * The exception table needs to be sorted so that the binary
- * search that we use to find entries in it works properly.
- * This is used both for the kernel exception table and for
- * the exception tables of modules that get loaded.
- *
- */
-static int cmp_ex(const void *a, const void *b)
-{
-       const struct exception_table_entry *x = a, *y = b;
-
-       /*
-        * This value will always end up fittin in an int, because on
-        * both i386 and x86-64 the kernel symbol-reachable address
-        * space is < 2 GiB.
-        *
-        * This compare is only valid after normalization.
-        */
-       return x->insn - y->insn;
-}
+       if (fixup_exception(regs, trapnr))
+               return;
 
-void sort_extable(struct exception_table_entry *start,
-                 struct exception_table_entry *finish)
-{
-       struct exception_table_entry *p;
-       int i;
-
-       /* Convert all entries to being relative to the start of the section */
-       i = 0;
-       for (p = start; p < finish; p++) {
-               p->insn += i;
-               i += 4;
-               p->fixup += i;
-               i += 4;
-               p->handler += i;
-               i += 4;
-       }
+fail:
+       early_printk("PANIC: early exception 0x%02x IP %lx:%lx error %lx cr2 0x%lx\n",
+                    (unsigned)trapnr, (unsigned long)regs->cs, regs->ip,
+                    regs->orig_ax, read_cr2());
 
-       sort(start, finish - start, sizeof(struct exception_table_entry),
-            cmp_ex, NULL);
-
-       /* Denormalize all entries */
-       i = 0;
-       for (p = start; p < finish; p++) {
-               p->insn -= i;
-               i += 4;
-               p->fixup -= i;
-               i += 4;
-               p->handler -= i;
-               i += 4;
-       }
-}
+       show_regs(regs);
 
-#ifdef CONFIG_MODULES
-/*
- * If the exception table is sorted, any referring to the module init
- * will be at the beginning or the end.
- */
-void trim_init_extable(struct module *m)
-{
-       /*trim the beginning*/
-       while (m->num_exentries &&
-              within_module_init(ex_insn_addr(&m->extable[0]), m)) {
-               m->extable++;
-               m->num_exentries--;
-       }
-       /*trim the end*/
-       while (m->num_exentries &&
-              within_module_init(ex_insn_addr(&m->extable[m->num_exentries-1]), m))
-               m->num_exentries--;
+halt_loop:
+       while (true)
+               halt();
 }
-#endif /* CONFIG_MODULES */