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

Pull x86 relocation changes from Ingo Molnar:
 "This tree contains a single change, ELF relocation handling in C - one
  of the kernel randomization patches that makes sense even without
  randomization present upstream"

* 'x86-kaslr-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86, relocs: Move ELF relocation handling to C

8 files changed, 97 insertions, 40 deletions

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index ff47e230d355..b710efdec9a0 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -1716,9 +1716,10 @@ config X86_NEED_RELOCS
         depends on X86_32 && RELOCATABLE
 
 config PHYSICAL_ALIGN
-        hex "Alignment value to which kernel should be aligned" if X86_32
+        hex "Alignment value to which kernel should be aligned"
         default "0x1000000"
-        range 0x2000 0x1000000
+        range 0x2000 0x1000000 if X86_32
+        range 0x200000 0x1000000 if X86_64
         ---help---
           This value puts the alignment restrictions on physical address
           where kernel is loaded and run from. Kernel is compiled for an
@@ -1736,6 +1737,9 @@ config PHYSICAL_ALIGN
           end result is that kernel runs from a physical address meeting
           above alignment restrictions.
 
+          On 32-bit this value must be a multiple of 0x2000. On 64-bit
+          this value must be a multiple of 0x200000.
+
           Don't change this unless you know what you are doing.
 
 config HOTPLUG_CPU
diff --git a/arch/x86/Makefile b/arch/x86/Makefile
index 07639c656fcd..41250fb33985 100644
--- a/arch/x86/Makefile
+++ b/arch/x86/Makefile
@@ -16,6 +16,10 @@ endif
 # e.g.: obj-y += foo_$(BITS).o
 export BITS
 
+ifdef CONFIG_X86_NEED_RELOCS
+        LDFLAGS_vmlinux := --emit-relocs
+endif
+
 ifeq ($(CONFIG_X86_32),y)
         BITS := 32
         UTS_MACHINE := i386
@@ -25,10 +29,6 @@ ifeq ($(CONFIG_X86_32),y)
         KBUILD_AFLAGS += $(biarch)
         KBUILD_CFLAGS += $(biarch)
 
-        ifdef CONFIG_RELOCATABLE
-                LDFLAGS_vmlinux := --emit-relocs
-        endif
-
         KBUILD_CFLAGS += -msoft-float -mregparm=3 -freg-struct-return
 
         # Never want PIC in a 32-bit kernel, prevent breakage with GCC built
diff --git a/arch/x86/boot/compressed/head_32.S b/arch/x86/boot/compressed/head_32.S
index 1e3184f6072f..5d6f6891b188 100644
--- a/arch/x86/boot/compressed/head_32.S
+++ b/arch/x86/boot/compressed/head_32.S
@@ -181,8 +181,9 @@ relocated:
 /*
  * Do the decompression, and jump to the new kernel..
  */
-        leal    z_extract_offset_negative(%ebx), %ebp
                                 /* push arguments for decompress_kernel: */
+        pushl   $z_output_len   /* decompressed length */
+        leal    z_extract_offset_negative(%ebx), %ebp
         pushl   %ebp            /* output address */
         pushl   $z_input_len    /* input_len */
         leal    input_data(%ebx), %eax
@@ -191,33 +192,7 @@ relocated:
         pushl   %eax            /* heap area */
         pushl   %esi            /* real mode pointer */
         call    decompress_kernel
-        addl    $20, %esp
-
-#if CONFIG_RELOCATABLE
-/*
- * Find the address of the relocations.
- */
-        leal    z_output_len(%ebp), %edi
-
-/*
- * Calculate the delta between where vmlinux was compiled to run
- * and where it was actually loaded.
- */
-        movl    %ebp, %ebx
-        subl    $LOAD_PHYSICAL_ADDR, %ebx
-        jz      2f      /* Nothing to be done if loaded at compiled addr. */
-/*
- * Process relocations.
- */
-
-1:      subl    $4, %edi
-        movl    (%edi), %ecx
-        testl   %ecx, %ecx
-        jz      2f
-        addl    %ebx, -__PAGE_OFFSET(%ebx, %ecx)
-        jmp     1b
-2:
-#endif
+        addl    $24, %esp
 
 /*
  * Jump to the decompressed kernel.
diff --git a/arch/x86/boot/compressed/head_64.S b/arch/x86/boot/compressed/head_64.S
index 06e71c2c16bf..c337422b575d 100644
--- a/arch/x86/boot/compressed/head_64.S
+++ b/arch/x86/boot/compressed/head_64.S
@@ -338,6 +338,7 @@ relocated:
         leaq    input_data(%rip), %rdx  /* input_data */
         movl    $z_input_len, %ecx      /* input_len */
         movq    %rbp, %r8               /* output target address */
+        movq    $z_output_len, %r9      /* decompressed length */
         call    decompress_kernel
         popq    %rsi
 
diff --git a/arch/x86/boot/compressed/misc.c b/arch/x86/boot/compressed/misc.c
index 0319c88290a5..434f077d2c4d 100644
--- a/arch/x86/boot/compressed/misc.c
+++ b/arch/x86/boot/compressed/misc.c
@@ -271,6 +271,79 @@ static void error(char *x)
                 asm("hlt");
 }
 
+#if CONFIG_X86_NEED_RELOCS
+static void handle_relocations(void *output, unsigned long output_len)
+{
+        int *reloc;
+        unsigned long delta, map, ptr;
+        unsigned long min_addr = (unsigned long)output;
+        unsigned long max_addr = min_addr + output_len;
+
+        /*
+         * Calculate the delta between where vmlinux was linked to load
+         * and where it was actually loaded.
+         */
+        delta = min_addr - LOAD_PHYSICAL_ADDR;
+        if (!delta) {
+                debug_putstr("No relocation needed... ");
+                return;
+        }
+        debug_putstr("Performing relocations... ");
+
+        /*
+         * The kernel contains a table of relocation addresses. Those
+         * addresses have the final load address of the kernel in virtual
+         * memory. We are currently working in the self map. So we need to
+         * create an adjustment for kernel memory addresses to the self map.
+         * This will involve subtracting out the base address of the kernel.
+         */
+        map = delta - __START_KERNEL_map;
+
+        /*
+         * Process relocations: 32 bit relocations first then 64 bit after.
+         * Two sets of binary relocations are added to the end of the kernel
+         * before compression. Each relocation table entry is the kernel
+         * address of the location which needs to be updated stored as a
+         * 32-bit value which is sign extended to 64 bits.
+         *
+         * Format is:
+         *
+         * kernel bits...
+         * 0 - zero terminator for 64 bit relocations
+         * 64 bit relocation repeated
+         * 0 - zero terminator for 32 bit relocations
+         * 32 bit relocation repeated
+         *
+         * So we work backwards from the end of the decompressed image.
+         */
+        for (reloc = output + output_len - sizeof(*reloc); *reloc; reloc--) {
+                int extended = *reloc;
+                extended += map;
+
+                ptr = (unsigned long)extended;
+                if (ptr < min_addr || ptr > max_addr)
+                        error("32-bit relocation outside of kernel!\n");
+
+                *(uint32_t *)ptr += delta;
+        }
+#ifdef CONFIG_X86_64
+        for (reloc--; *reloc; reloc--) {
+                long extended = *reloc;
+                extended += map;
+
+                ptr = (unsigned long)extended;
+                if (ptr < min_addr || ptr > max_addr)
+                        error("64-bit relocation outside of kernel!\n");