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authorLinus Torvalds <torvalds@linux-foundation.org>2016-04-14 19:53:46 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2016-04-14 19:53:46 -0700
commit806fdcce017dc98c4dbf8ed001750a0d7d2bb0af (patch)
tree9cf2e221546d26219e5f83fff40f5be6e545f377 /arch
parenta1f983174dd7e535e50ca850fcfb3b8d38149f39 (diff)
parenta3125494cff084b098c80bb36fbe2061ffed9d52 (diff)
downloadlinux-sh-806fdcce017dc98c4dbf8ed001750a0d7d2bb0af.tar.gz
Merge branch 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 fixes from Ingo Molnar: "Misc fixes: a binutils fix, an lguest fix, an mcelog fix and a missing documentation fix" * 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: x86/mce: Avoid using object after free in genpool lguest, x86/entry/32: Fix handling of guest syscalls using interrupt gates x86/build: Build compressed x86 kernels as PIE x86/mm/pkeys: Add missing Documentation
Diffstat (limited to 'arch')
-rw-r--r--arch/x86/boot/compressed/Makefile14
-rw-r--r--arch/x86/boot/compressed/head_32.S28
-rw-r--r--arch/x86/boot/compressed/head_64.S8
-rw-r--r--arch/x86/kernel/cpu/mcheck/mce-genpool.c4
4 files changed, 51 insertions, 3 deletions
diff --git a/arch/x86/boot/compressed/Makefile b/arch/x86/boot/compressed/Makefile
index 6915ff2bd996..8774cb23064f 100644
--- a/arch/x86/boot/compressed/Makefile
+++ b/arch/x86/boot/compressed/Makefile
@@ -26,7 +26,7 @@ targets := vmlinux vmlinux.bin vmlinux.bin.gz vmlinux.bin.bz2 vmlinux.bin.lzma \
vmlinux.bin.xz vmlinux.bin.lzo vmlinux.bin.lz4
KBUILD_CFLAGS := -m$(BITS) -D__KERNEL__ $(LINUX_INCLUDE) -O2
-KBUILD_CFLAGS += -fno-strict-aliasing -fPIC
+KBUILD_CFLAGS += -fno-strict-aliasing $(call cc-option, -fPIE, -fPIC)
KBUILD_CFLAGS += -DDISABLE_BRANCH_PROFILING
cflags-$(CONFIG_X86_32) := -march=i386
cflags-$(CONFIG_X86_64) := -mcmodel=small
@@ -40,6 +40,18 @@ GCOV_PROFILE := n
UBSAN_SANITIZE :=n
LDFLAGS := -m elf_$(UTS_MACHINE)
+ifeq ($(CONFIG_RELOCATABLE),y)
+# If kernel is relocatable, build compressed kernel as PIE.
+ifeq ($(CONFIG_X86_32),y)
+LDFLAGS += $(call ld-option, -pie) $(call ld-option, --no-dynamic-linker)
+else
+# To build 64-bit compressed kernel as PIE, we disable relocation
+# overflow check to avoid relocation overflow error with a new linker
+# command-line option, -z noreloc-overflow.
+LDFLAGS += $(shell $(LD) --help 2>&1 | grep -q "\-z noreloc-overflow" \
+ && echo "-z noreloc-overflow -pie --no-dynamic-linker")
+endif
+endif
LDFLAGS_vmlinux := -T
hostprogs-y := mkpiggy
diff --git a/arch/x86/boot/compressed/head_32.S b/arch/x86/boot/compressed/head_32.S
index 8ef964ddc18e..0256064da8da 100644
--- a/arch/x86/boot/compressed/head_32.S
+++ b/arch/x86/boot/compressed/head_32.S
@@ -31,6 +31,34 @@
#include <asm/asm-offsets.h>
#include <asm/bootparam.h>
+/*
+ * The 32-bit x86 assembler in binutils 2.26 will generate R_386_GOT32X
+ * relocation to get the symbol address in PIC. When the compressed x86
+ * kernel isn't built as PIC, the linker optimizes R_386_GOT32X
+ * relocations to their fixed symbol addresses. However, when the
+ * compressed x86 kernel is loaded at a different address, it leads
+ * to the following load failure:
+ *
+ * Failed to allocate space for phdrs
+ *
+ * during the decompression stage.
+ *
+ * If the compressed x86 kernel is relocatable at run-time, it should be
+ * compiled with -fPIE, instead of -fPIC, if possible and should be built as
+ * Position Independent Executable (PIE) so that linker won't optimize
+ * R_386_GOT32X relocation to its fixed symbol address. Older
+ * linkers generate R_386_32 relocations against locally defined symbols,
+ * _bss, _ebss, _got and _egot, in PIE. It isn't wrong, just less
+ * optimal than R_386_RELATIVE. But the x86 kernel fails to properly handle
+ * R_386_32 relocations when relocating the kernel. To generate
+ * R_386_RELATIVE relocations, we mark _bss, _ebss, _got and _egot as
+ * hidden:
+ */
+ .hidden _bss
+ .hidden _ebss
+ .hidden _got
+ .hidden _egot
+
__HEAD
ENTRY(startup_32)
#ifdef CONFIG_EFI_STUB
diff --git a/arch/x86/boot/compressed/head_64.S b/arch/x86/boot/compressed/head_64.S
index b0c0d16ef58d..86558a199139 100644
--- a/arch/x86/boot/compressed/head_64.S
+++ b/arch/x86/boot/compressed/head_64.S
@@ -33,6 +33,14 @@
#include <asm/asm-offsets.h>
#include <asm/bootparam.h>
+/*
+ * Locally defined symbols should be marked hidden:
+ */
+ .hidden _bss
+ .hidden _ebss
+ .hidden _got
+ .hidden _egot
+
__HEAD
.code32
ENTRY(startup_32)
diff --git a/arch/x86/kernel/cpu/mcheck/mce-genpool.c b/arch/x86/kernel/cpu/mcheck/mce-genpool.c
index 0a850100c594..2658e2af74ec 100644
--- a/arch/x86/kernel/cpu/mcheck/mce-genpool.c
+++ b/arch/x86/kernel/cpu/mcheck/mce-genpool.c
@@ -29,7 +29,7 @@ static char gen_pool_buf[MCE_POOLSZ];
void mce_gen_pool_process(void)
{
struct llist_node *head;
- struct mce_evt_llist *node;
+ struct mce_evt_llist *node, *tmp;
struct mce *mce;
head = llist_del_all(&mce_event_llist);
@@ -37,7 +37,7 @@ void mce_gen_pool_process(void)
return;
head = llist_reverse_order(head);
- llist_for_each_entry(node, head, llnode) {
+ llist_for_each_entry_safe(node, tmp, head, llnode) {
mce = &node->mce;
atomic_notifier_call_chain(&x86_mce_decoder_chain, 0, mce);
gen_pool_free(mce_evt_pool, (unsigned long)node, sizeof(*node));