1 files changed, 65 insertions, 14 deletions

diff --git a/arch/powerpc/lib/feature-fixups.c b/arch/powerpc/lib/feature-fixups.c
index 973d547ef01d..174c1eba9ac8 100644
--- a/arch/powerpc/lib/feature-fixups.c
+++ b/arch/powerpc/lib/feature-fixups.c
@@ -26,24 +26,66 @@ struct fixup_entry {
         long            alt_end_off;
 };
 
-static void patch_feature_section(unsigned long value, struct fixup_entry *fcur)
+static unsigned int *calc_addr(struct fixup_entry *fcur, long offset)
 {
-        unsigned int *pstart, *pend, *p;
+        /*
+         * We store the offset to the code as a negative offset from
+         * the start of the alt_entry, to support the VDSO. This
+         * routine converts that back into an actual address.
+         */
+        return (unsigned int *)((unsigned long)fcur + offset);
+}
+
+static int patch_alt_instruction(unsigned int *src, unsigned int *dest,
+                                 unsigned int *alt_start, unsigned int *alt_end)
+{
+        unsigned int instr;
+
+        instr = *src;
+
+        if (instr_is_relative_branch(*src)) {
+                unsigned int *target = (unsigned int *)branch_target(src);
+
+                /* Branch within the section doesn't need translating */
+                if (target < alt_start || target >= alt_end) {
+                        instr = translate_branch(dest, src);
+                        if (!instr)
+                                return 1;
+                }
+        }
+
+        patch_instruction(dest, instr);
+
+        return 0;
+}
+
+static int patch_feature_section(unsigned long value, struct fixup_entry *fcur)
+{
+        unsigned int *start, *end, *alt_start, *alt_end, *src, *dest;
+
+        start = calc_addr(fcur, fcur->start_off);
+        end = calc_addr(fcur, fcur->end_off);
+        alt_start = calc_addr(fcur, fcur->alt_start_off);
+        alt_end = calc_addr(fcur, fcur->alt_end_off);
+
+        if ((alt_end - alt_start) > (end - start))
+                return 1;
 
         if ((value & fcur->mask) == fcur->value)
-                return;
+                return 0;
 
-        pstart = ((unsigned int *)fcur) + (fcur->start_off / 4);
-        pend = ((unsigned int *)fcur) + (fcur->end_off / 4);
+        src = alt_start;
+        dest = start;
 
-        for (p = pstart; p < pend; p++) {
-                *p = PPC_NOP_INSTR;
-                asm volatile ("dcbst 0, %0" : : "r" (p));
+        for (; src < alt_end; src++, dest++) {
+                if (patch_alt_instruction(src, dest, alt_start, alt_end))
+                        return 1;
         }
-        asm volatile ("sync" : : : "memory");
-        for (p = pstart; p < pend; p++)
-                asm volatile ("icbi 0,%0" : : "r" (p));
-        asm volatile ("sync; isync" : : : "memory");
+
+        for (; dest < end; dest++)
+                patch_instruction(dest, PPC_NOP_INSTR);
+
+        return 0;
 }
 
 void do_feature_fixups(unsigned long value, void *fixup_start, void *fixup_end)
@@ -53,6 +95,15 @@ void do_feature_fixups(unsigned long value, void *fixup_start, void *fixup_end)
         fcur = fixup_start;
         fend = fixup_end;
 
-        for (; fcur < fend; fcur++)
-                patch_feature_section(value, fcur);
+        for (; fcur < fend; fcur++) {
+                if (patch_feature_section(value, fcur)) {
+                        __WARN();
+                        printk("Unable to patch feature section at %p - %p" \
+                                " with %p - %p\n",
+                                calc_addr(fcur, fcur->start_off),
+                                calc_addr(fcur, fcur->end_off),
+                                calc_addr(fcur, fcur->alt_start_off),
+                                calc_addr(fcur, fcur->alt_end_off));
+                }
+        }
 }