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Commit 2a8a2b7c authored by Linus Torvalds's avatar Linus Torvalds
Browse files

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

Pull x86 fixes from Thomas Gleixner:

 - Correct the L1TF fallout on 32bit and the off by one in the 'too much
   RAM for protection' calculation.

 - Add a helpful kernel message for the 'too much RAM' case

 - Unbreak the VDSO in case that the compiler desides to use indirect
   jumps/calls and emits retpolines which cannot be resolved because the
   kernel uses its own thunks, which does not work for the VDSO. Make it
   use the builtin thunks.

 - Re-export start_thread() which was unexported when the 32/64bit
   implementation was unified. start_thread() is required by modular
   binfmt handlers.

 - Trivial cleanups

* 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/speculation/l1tf: Suggest what to do on systems with too much RAM
  x86/speculation/l1tf: Fix off-by-one error when warning that system has too much RAM
  x86/kvm/vmx: Remove duplicate l1d flush definitions
  x86/speculation/l1tf: Fix overflow in l1tf_pfn_limit() on 32bit
  x86/process: Re-export start_thread()
  x86/mce: Add notifier_block forward declaration
  x86/vdso: Fix vDSO build if a retpoline is emitted
parents de375035 6a012288

Makefile

+4 −0
Original line number Diff line number Diff line
@@ -507,9 +507,13 @@ KBUILD_AFLAGS += $(call cc-option, -no-integrated-as) 
endif



RETPOLINE_CFLAGS_GCC := -mindirect-branch=thunk-extern -mindirect-branch-register

RETPOLINE_VDSO_CFLAGS_GCC := -mindirect-branch=thunk-inline -mindirect-branch-register

RETPOLINE_CFLAGS_CLANG := -mretpoline-external-thunk

RETPOLINE_VDSO_CFLAGS_CLANG := -mretpoline

RETPOLINE_CFLAGS := $(call cc-option,$(RETPOLINE_CFLAGS_GCC),$(call cc-option,$(RETPOLINE_CFLAGS_CLANG)))

RETPOLINE_VDSO_CFLAGS := $(call cc-option,$(RETPOLINE_VDSO_CFLAGS_GCC),$(call cc-option,$(RETPOLINE_VDSO_CFLAGS_CLANG)))

export RETPOLINE_CFLAGS

export RETPOLINE_VDSO_CFLAGS



KBUILD_CFLAGS	+= $(call cc-option,-fno-PIE)

KBUILD_AFLAGS	+= $(call cc-option,-fno-PIE)

arch/x86/entry/vdso/Makefile

+4 −2
Original line number Diff line number Diff line
@@ -68,9 +68,9 @@ $(obj)/vdso-image-%.c: $(obj)/vdso%.so.dbg $(obj)/vdso%.so $(obj)/vdso2c FORCE 
CFL := $(PROFILING) -mcmodel=small -fPIC -O2 -fasynchronous-unwind-tables -m64 \

       $(filter -g%,$(KBUILD_CFLAGS)) $(call cc-option, -fno-stack-protector) \

       -fno-omit-frame-pointer -foptimize-sibling-calls \

       -DDISABLE_BRANCH_PROFILING -DBUILD_VDSO

       -DDISABLE_BRANCH_PROFILING -DBUILD_VDSO $(RETPOLINE_VDSO_CFLAGS)



$(vobjs): KBUILD_CFLAGS := $(filter-out $(GCC_PLUGINS_CFLAGS),$(KBUILD_CFLAGS)) $(CFL)

$(vobjs): KBUILD_CFLAGS := $(filter-out $(GCC_PLUGINS_CFLAGS) $(RETPOLINE_CFLAGS),$(KBUILD_CFLAGS)) $(CFL)



#

# vDSO code runs in userspace and -pg doesn't help with profiling anyway.
@@ -132,11 +132,13 @@ KBUILD_CFLAGS_32 := $(filter-out -mcmodel=kernel,$(KBUILD_CFLAGS_32)) 
KBUILD_CFLAGS_32 := $(filter-out -fno-pic,$(KBUILD_CFLAGS_32))

KBUILD_CFLAGS_32 := $(filter-out -mfentry,$(KBUILD_CFLAGS_32))

KBUILD_CFLAGS_32 := $(filter-out $(GCC_PLUGINS_CFLAGS),$(KBUILD_CFLAGS_32))

KBUILD_CFLAGS_32 := $(filter-out $(RETPOLINE_CFLAGS),$(KBUILD_CFLAGS_32))

KBUILD_CFLAGS_32 += -m32 -msoft-float -mregparm=0 -fpic

KBUILD_CFLAGS_32 += $(call cc-option, -fno-stack-protector)

KBUILD_CFLAGS_32 += $(call cc-option, -foptimize-sibling-calls)

KBUILD_CFLAGS_32 += -fno-omit-frame-pointer

KBUILD_CFLAGS_32 += -DDISABLE_BRANCH_PROFILING

KBUILD_CFLAGS_32 += $(RETPOLINE_VDSO_CFLAGS)

$(obj)/vdso32.so.dbg: KBUILD_CFLAGS = $(KBUILD_CFLAGS_32)



$(obj)/vdso32.so.dbg: FORCE \

arch/x86/include/asm/mce.h

+1 −0
Original line number Diff line number Diff line
@@ -148,6 +148,7 @@ enum mce_notifier_prios { 
	MCE_PRIO_LOWEST		= 0,

};



struct notifier_block;

extern void mce_register_decode_chain(struct notifier_block *nb);

extern void mce_unregister_decode_chain(struct notifier_block *nb);

arch/x86/include/asm/processor.h

+2 −2
Original line number Diff line number Diff line
@@ -181,9 +181,9 @@ extern const struct seq_operations cpuinfo_op; 


extern void cpu_detect(struct cpuinfo_x86 *c);



static inline unsigned long l1tf_pfn_limit(void)

static inline unsigned long long l1tf_pfn_limit(void)

{

	return BIT(boot_cpu_data.x86_phys_bits - 1 - PAGE_SHIFT) - 1;

	return BIT_ULL(boot_cpu_data.x86_phys_bits - 1 - PAGE_SHIFT);

}



extern void early_cpu_init(void);

arch/x86/kernel/cpu/bugs.c

+4 −0
Original line number Diff line number Diff line
@@ -702,6 +702,10 @@ static void __init l1tf_select_mitigation(void) 
	half_pa = (u64)l1tf_pfn_limit() << PAGE_SHIFT;

	if (e820__mapped_any(half_pa, ULLONG_MAX - half_pa, E820_TYPE_RAM)) {

		pr_warn("System has more than MAX_PA/2 memory. L1TF mitigation not effective.\n");

		pr_info("You may make it effective by booting the kernel with mem=%llu parameter.\n",

				half_pa);

		pr_info("However, doing so will make a part of your RAM unusable.\n");

		pr_info("Reading https://www.kernel.org/doc/html/latest/admin-guide/l1tf.html might help you decide.\n");

		return;

	}