Merge branch 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip (806fdcce) · Commits · 戴 / test

Documentation/x86/protection-keys.txt

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		Memory Protection Keys for Userspace (PKU aka PKEYs) is a CPU feature
		which will be found on future Intel CPUs.

		Memory Protection Keys provides a mechanism for enforcing page-based
		protections, but without requiring modification of the page tables
		when an application changes protection domains. It works by
		dedicating 4 previously ignored bits in each page table entry to a
		"protection key", giving 16 possible keys.

		There is also a new user-accessible register (PKRU) with two separate
		bits (Access Disable and Write Disable) for each key. Being a CPU
		register, PKRU is inherently thread-local, potentially giving each
		thread a different set of protections from every other thread.

		There are two new instructions (RDPKRU/WRPKRU) for reading and writing
		to the new register. The feature is only available in 64-bit mode,
		even though there is theoretically space in the PAE PTEs. These
		permissions are enforced on data access only and have no effect on
		instruction fetches.

		=========================== Config Option ===========================

		This config option adds approximately 1.5kb of text. and 50 bytes of
		data to the executable. A workload which does large O_DIRECT reads
		of holes in XFS files was run to exercise get_user_pages_fast(). No
		performance delta was observed with the config option
		enabled or disabled.

+13 −1

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		@@ -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

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		@@ -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

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		@@ -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)

+2 −2

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		@@ -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));