Merge branch 'x86-extable-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull exception table generation updates from Ingo Molnar:
 "The biggest change here is to allow the build-time sorting of the
  exception table, to speed up booting.  This is achieved by the
  architecture enabling BUILDTIME_EXTABLE_SORT.  This option is enabled
  for x86 and MIPS currently.

  On x86 a number of fixes and changes were needed to allow build-time
  sorting of the exception table, in particular a relocation invariant
  exception table format was needed.  This required the abstracting out
  of exception table protocol and the removal of 20 years of accumulated
  assumptions about the x86 exception table format.

  While at it, this tree also cleans up various other aspects of
  exception handling, such as early(er) exception handling for
  rdmsr_safe() et al.

  All in one, as the result of these changes the x86 exception code is
  now pretty nice and modern.  As an added bonus any regressions in this
  code will be early and violent crashes, so if you see any of those,
  you'll know whom to blame!"

Fix up trivial conflicts in arch/{mips,x86}/Kconfig files due to nearby
modifications of other core architecture options.

* 'x86-extable-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (35 commits)
  Revert "x86, extable: Disable presorted exception table for now"
  scripts/sortextable: Handle relative entries, and other cleanups
  x86, extable: Switch to relative exception table entries
  x86, extable: Disable presorted exception table for now
  x86, extable: Add _ASM_EXTABLE_EX() macro
  x86, extable: Remove open-coded exception table entries in arch/x86/ia32/ia32entry.S
  x86, extable: Remove open-coded exception table entries in arch/x86/include/asm/xsave.h
  x86, extable: Remove open-coded exception table entries in arch/x86/include/asm/kvm_host.h
  x86, extable: Remove the now-unused __ASM_EX_SEC macros
  x86, extable: Remove open-coded exception table entries in arch/x86/xen/xen-asm_32.S
  x86, extable: Remove open-coded exception table entries in arch/x86/um/checksum_32.S
  x86, extable: Remove open-coded exception table entries in arch/x86/lib/usercopy_32.c
  x86, extable: Remove open-coded exception table entries in arch/x86/lib/putuser.S
  x86, extable: Remove open-coded exception table entries in arch/x86/lib/getuser.S
  x86, extable: Remove open-coded exception table entries in arch/x86/lib/csum-copy_64.S
  x86, extable: Remove open-coded exception table entries in arch/x86/lib/copy_user_nocache_64.S
  x86, extable: Remove open-coded exception table entries in arch/x86/lib/copy_user_64.S
  x86, extable: Remove open-coded exception table entries in arch/x86/lib/checksum_32.S
  x86, extable: Remove open-coded exception table entries in arch/x86/kernel/test_rodata.c
  x86, extable: Remove open-coded exception table entries in arch/x86/kernel/entry_64.S
  ...

1 files changed, 137 insertions, 5 deletions

diff --git a/arch/x86/mm/extable.c b/arch/x86/mm/extable.c
index 1fb85dbe390a..903ec1e9c326 100644
--- a/arch/x86/mm/extable.c
+++ b/arch/x86/mm/extable.c
@@ -1,11 +1,23 @@
 #include <linux/module.h>
 #include <linux/spinlock.h>
+#include <linux/sort.h>
 #include <asm/uaccess.h>
 
+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)
+{
+        return (unsigned long)&x->fixup + x->fixup;
+}
 
 int fixup_exception(struct pt_regs *regs)
 {
         const struct exception_table_entry *fixup;
+        unsigned long new_ip;
 
 #ifdef CONFIG_PNPBIOS
         if (unlikely(SEGMENT_IS_PNP_CODE(regs->cs))) {
@@ -23,15 +35,135 @@ int fixup_exception(struct pt_regs *regs)
 
         fixup = search_exception_tables(regs->ip);
         if (fixup) {
-                /* If fixup is less than 16, it means uaccess error */
-                if (fixup->fixup < 16) {
+                new_ip = ex_fixup_addr(fixup);
+
+                if (fixup->fixup - fixup->insn >= 0x7ffffff0 - 4) {
+                        /* Special hack for uaccess_err */
                         current_thread_info()->uaccess_err = 1;
-                        regs->ip += fixup->fixup;
-                        return 1;
+                        new_ip -= 0x7ffffff0;
                 }
-                regs->ip = fixup->fixup;
+                regs->ip = new_ip;
                 return 1;
         }
 
         return 0;
 }
+
+/* Restricted version used during very early boot */
+int __init early_fixup_exception(unsigned long *ip)
+{
+        const struct exception_table_entry *fixup;
+        unsigned long new_ip;
+
+        fixup = search_exception_tables(*ip);
+        if (fixup) {
+                new_ip = ex_fixup_addr(fixup);
+
+                if (fixup->fixup - fixup->insn >= 0x7ffffff0 - 4) {
+                        /* uaccess handling not supported during early boot */
+                        return 0;
+                }
+
+                *ip = new_ip;
+                return 1;
+        }
+
+        return 0;
+}
+
+/*
+ * 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;
+}
+
+/*
+ * 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;
+}
+
+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;
+        }
+
+        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;
+        }
+}
+
+#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--;
+}
+#endif /* CONFIG_MODULES */