Ramya

Documentation/admin-guide/hw-vuln/spectre.rst

@@ -41,10 +41,11 @@ Related CVEs
 
 The following CVE entries describe Spectre variants:
 
-   =============   =======================  =================
+   =============   =======================  ==========================
    CVE-2017-5753   Bounds check bypass      Spectre variant 1
    CVE-2017-5715   Branch target injection  Spectre variant 2
-   =============   =======================  =================
+   CVE-2019-1125   Spectre v1 swapgs        Spectre variant 1 (swapgs)
+   =============   =======================  ==========================
 
 Problem
 -------
@@ -78,6 +79,13 @@ There are some extensions of Spectre variant 1 attacks for reading data
 over the network, see :ref:`[12] <spec_ref12>`. However such attacks
 are difficult, low bandwidth, fragile, and are considered low risk.
 
+Note that, despite "Bounds Check Bypass" name, Spectre variant 1 is not
+only about user-controlled array bounds checks.  It can affect any
+conditional checks.  The kernel entry code interrupt, exception, and NMI
+handlers all have conditional swapgs checks.  Those may be problematic
+in the context of Spectre v1, as kernel code can speculatively run with
+a user GS.
+
 Spectre variant 2 (Branch Target Injection)
 -------------------------------------------
 
@@ -132,6 +140,9 @@ not cover all possible attack vectors.
 1. A user process attacking the kernel
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
+Spectre variant 1
+~~~~~~~~~~~~~~~~~
+
    The attacker passes a parameter to the kernel via a register or
    via a known address in memory during a syscall. Such parameter may
    be used later by the kernel as an index to an array or to derive
@@ -144,7 +155,40 @@ not cover all possible attack vectors.
    potentially be influenced for Spectre attacks, new "nospec" accessor
    macros are used to prevent speculative loading of data.
 
-   Spectre variant 2 attacker can :ref:`poison <poison_btb>` the branch
+Spectre variant 1 (swapgs)
+~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+   An attacker can train the branch predictor to speculatively skip the
+   swapgs path for an interrupt or exception.  If they initialize
+   the GS register to a user-space value, if the swapgs is speculatively
+   skipped, subsequent GS-related percpu accesses in the speculation
+   window will be done with the attacker-controlled GS value.  This
+   could cause privileged memory to be accessed and leaked.
+
+   For example:
+
+   ::
+
+     if (coming from user space)
+         swapgs
+     mov %gs:<percpu_offset>, %reg
+     mov (%reg), %reg1
+
+   When coming from user space, the CPU can speculatively skip the
+   swapgs, and then do a speculative percpu load using the user GS
+   value.  So the user can speculatively force a read of any kernel
+   value.  If a gadget exists which uses the percpu value as an address
+   in another load/store, then the contents of the kernel value may
+   become visible via an L1 side channel attack.
+
+   A similar attack exists when coming from kernel space.  The CPU can
+   speculatively do the swapgs, causing the user GS to get used for the
+   rest of the speculative window.
+
+Spectre variant 2
+~~~~~~~~~~~~~~~~~
+
+   A spectre variant 2 attacker can :ref:`poison <poison_btb>` the branch
    target buffer (BTB) before issuing syscall to launch an attack.
    After entering the kernel, the kernel could use the poisoned branch
    target buffer on indirect jump and jump to gadget code in speculative
@@ -280,11 +324,18 @@ The sysfs file showing Spectre variant 1 mitigation status is:
 
 The possible values in this file are:
 
-  =======================================  =================================
-  'Mitigation: __user pointer sanitation'  Protection in kernel on a case by
-                                           case base with explicit pointer
-                                           sanitation.
-  =======================================  =================================
+  .. list-table::
+
+     * - 'Not affected'
+       - The processor is not vulnerable.
+     * - 'Vulnerable: __user pointer sanitization and usercopy barriers only; no swapgs barriers'
+       - The swapgs protections are disabled; otherwise it has
+         protection in the kernel on a case by case base with explicit
+         pointer sanitation and usercopy LFENCE barriers.
+     * - 'Mitigation: usercopy/swapgs barriers and __user pointer sanitization'
+       - Protection in the kernel on a case by case base with explicit
+         pointer sanitation, usercopy LFENCE barriers, and swapgs LFENCE
+         barriers.
 
 However, the protections are put in place on a case by case basis,
 and there is no guarantee that all possible attack vectors for Spectre
@@ -366,12 +417,27 @@ Turning on mitigation for Spectre variant 1 and Spectre variant 2
 1. Kernel mitigation
 ^^^^^^^^^^^^^^^^^^^^
 
+Spectre variant 1
+~~~~~~~~~~~~~~~~~
+
    For the Spectre variant 1, vulnerable kernel code (as determined
    by code audit or scanning tools) is annotated on a case by case
    basis to use nospec accessor macros for bounds clipping :ref:`[2]
    <spec_ref2>` to avoid any usable disclosure gadgets. However, it may
    not cover all attack vectors for Spectre variant 1.
 
+   Copy-from-user code has an LFENCE barrier to prevent the access_ok()
+   check from being mis-speculated.  The barrier is done by the
+   barrier_nospec() macro.
+
+   For the swapgs variant of Spectre variant 1, LFENCE barriers are
+   added to interrupt, exception and NMI entry where needed.  These
+   barriers are done by the FENCE_SWAPGS_KERNEL_ENTRY and
+   FENCE_SWAPGS_USER_ENTRY macros.
+
+Spectre variant 2
+~~~~~~~~~~~~~~~~~
+
    For Spectre variant 2 mitigation, the compiler turns indirect calls or
    jumps in the kernel into equivalent return trampolines (retpolines)
    :ref:`[3] <spec_ref3>` :ref:`[9] <spec_ref9>` to go to the target
@@ -473,6 +539,12 @@ Mitigation control on the kernel command line
 Spectre variant 2 mitigation can be disabled or force enabled at the
 kernel command line.
 
+	nospectre_v1
+
+		[X86,PPC] Disable mitigations for Spectre Variant 1
+		(bounds check bypass). With this option data leaks are
+		possible in the system.
+
 	nospectre_v2
 
 		[X86] Disable all mitigations for the Spectre variant 2

Documentation/admin-guide/kernel-parameters.txt

@@ -2522,6 +2522,7 @@
 				Equivalent to: nopti [X86,PPC]
 					       nospectre_v1 [PPC]
 					       nobp=0 [S390]
+					       nospectre_v1 [X86]
 					       nospectre_v2 [X86,PPC,S390]
 					       spectre_v2_user=off [X86]
 					       spec_store_bypass_disable=off [X86,PPC]
@@ -2868,9 +2869,9 @@
 			nosmt=force: Force disable SMT, cannot be undone
 				     via the sysfs control file.
 
-	nospectre_v1	[PPC] Disable mitigations for Spectre Variant 1 (bounds
-			check bypass). With this option data leaks are possible
-			in the system.
+	nospectre_v1	[X66, PPC] Disable mitigations for Spectre Variant 1
+			(bounds check bypass). With this option data leaks
+			are possible in the system.
 
 	nospectre_v2	[X86,PPC_FSL_BOOK3E] Disable all mitigations for the Spectre variant 2
 			(indirect branch prediction) vulnerability. System may
@@ -3962,6 +3963,13 @@
 			Run specified binary instead of /init from the ramdisk,
 			used for early userspace startup. See initrd.
 
+	rdrand=		[X86]
+			force - Override the decision by the kernel to hide the
+				advertisement of RDRAND support (this affects
+				certain AMD processors because of buggy BIOS
+				support, specifically around the suspend/resume
+				path).
+
 	rdt=		[HW,X86,RDT]
 			Turn on/off individual RDT features. List is:
 			cmt, mbmtotal, mbmlocal, l3cat, l3cdp, l2cat, l2cdp,

Documentation/devicetree/bindings/display/panel/armadeus,st0700-adapt.txt

@@ -0,0 +1,9 @@
+Armadeus ST0700 Adapt. A Santek ST0700I5Y-RBSLW 7.0" WVGA (800x480) TFT with
+an adapter board.
+
+Required properties:
+- compatible: "armadeus,st0700-adapt"
+- power-supply: see panel-common.txt
+
+Optional properties:
+- backlight: see panel-common.txt

Documentation/devicetree/bindings/iio/adc/samsung,exynos-adc.txt

@@ -11,11 +11,13 @@ New driver handles the following
 
 Required properties:
 - compatible:		Must be "samsung,exynos-adc-v1"
-				for exynos4412/5250 and s5pv210 controllers.
+				for Exynos5250 controllers.
 			Must be "samsung,exynos-adc-v2" for
 				future controllers.
 			Must be "samsung,exynos3250-adc" for
 				controllers compatible with ADC of Exynos3250.
+			Must be "samsung,exynos4212-adc" for
+				controllers compatible with ADC of Exynos4212 and Exynos4412.
 			Must be "samsung,exynos7-adc" for
 				the ADC in Exynos7 and compatibles
 			Must be "samsung,s3c2410-adc" for
@@ -28,6 +30,8 @@ Required properties:
 				the ADC in s3c2443 and compatibles
 			Must be "samsung,s3c6410-adc" for
 				the ADC in s3c6410 and compatibles
+			Must be "samsung,s5pv210-adc" for
+				the ADC in s5pv210 and compatibles
 - reg:			List of ADC register address range
 			- The base address and range of ADC register
 			- The base address and range of ADC_PHY register (every

Documentation/devicetree/bindings/mmc/mmc.txt

@@ -62,6 +62,10 @@ Optional properties:
   be referred to mmc-pwrseq-simple.txt. But now it's reused as a tunable delay
   waiting for I/O signalling and card power supply to be stable, regardless of
   whether pwrseq-simple is used. Default to 10ms if no available.
+- supports-cqe : The presence of this property indicates that the corresponding
+  MMC host controller supports HW command queue feature.
+- disable-cqe-dcmd: This property indicates that the MMC controller's command
+  queue engine (CQE) does not support direct commands (DCMDs).
 
 *NOTE* on CD and WP polarity. To use common for all SD/MMC host controllers line
 polarity properties, we have to fix the meaning of the "normal" and "inverted"

Makefile

@@ -1,7 +1,7 @@
 # SPDX-License-Identifier: GPL-2.0
 VERSION = 4
 PATCHLEVEL = 19
-SUBLEVEL = 62
+SUBLEVEL = 73
 EXTRAVERSION =
 NAME = "People's Front"
 
@@ -430,6 +430,7 @@ KBUILD_CFLAGS_MODULE  := -DMODULE
 KBUILD_LDFLAGS_MODULE := -T $(srctree)/scripts/module-common.lds
 KBUILD_LDFLAGS :=
 GCC_PLUGINS_CFLAGS :=
+CLANG_FLAGS :=
 
 export ARCH SRCARCH CONFIG_SHELL HOSTCC KBUILD_HOSTCFLAGS CROSS_COMPILE AS LD CC
 export CPP AR NM STRIP OBJCOPY OBJDUMP KBUILD_HOSTLDFLAGS KBUILD_HOSTLDLIBS
@@ -483,7 +484,7 @@ endif
 ifeq ($(cc-name),clang)
 ifneq ($(CROSS_COMPILE),)
 CLANG_TRIPLE	?= $(CROSS_COMPILE)
-CLANG_FLAGS	:= --target=$(notdir $(CLANG_TRIPLE:%-=%))
+CLANG_FLAGS	+= --target=$(notdir $(CLANG_TRIPLE:%-=%))
 GCC_TOOLCHAIN_DIR := $(dir $(shell which $(LD)))
 CLANG_FLAGS	+= --prefix=$(GCC_TOOLCHAIN_DIR)
 GCC_TOOLCHAIN	:= $(realpath $(GCC_TOOLCHAIN_DIR)/..)
@@ -492,6 +493,7 @@ ifneq ($(GCC_TOOLCHAIN),)
 CLANG_FLAGS	+= --gcc-toolchain=$(GCC_TOOLCHAIN)
 endif
 CLANG_FLAGS	+= -no-integrated-as
+CLANG_FLAGS	+= -Werror=unknown-warning-option
 KBUILD_CFLAGS	+= $(CLANG_FLAGS)
 KBUILD_AFLAGS	+= $(CLANG_FLAGS)
 export CLANG_FLAGS
@@ -698,11 +700,8 @@ ifeq ($(cc-name),clang)
 KBUILD_CPPFLAGS += $(call cc-option,-Qunused-arguments,)
 KBUILD_CFLAGS += $(call cc-disable-warning, format-invalid-specifier)
 KBUILD_CFLAGS += $(call cc-disable-warning, gnu)
-<<<<<<< HEAD
 KBUILD_CFLAGS += $(call cc-disable-warning, address-of-packed-member)
 KBUILD_CFLAGS += $(call cc-disable-warning, duplicate-decl-specifier)
-=======
->>>>>>> v4.19.57
 # Quiet clang warning: comparison of unsigned expression < 0 is always false
 KBUILD_CFLAGS += $(call cc-disable-warning, tautological-compare)
 # CLANG uses a _MergedGlobals as optimization, but this breaks modpost, as the

arch/arc/Kconfig

@@ -199,7 +199,6 @@ config NR_CPUS
 
 config ARC_SMP_HALT_ON_RESET
 	bool "Enable Halt-on-reset boot mode"
-	default y if ARC_UBOOT_SUPPORT
 	help
 	  In SMP configuration cores can be configured as Halt-on-reset
 	  or they could all start at same time. For Halt-on-reset, non
@@ -539,18 +538,6 @@ config ARC_DBG_TLB_PARANOIA
 
 endif
 
-config ARC_UBOOT_SUPPORT
-	bool "Support uboot arg Handling"
-	default n
-	help
-	  ARC Linux by default checks for uboot provided args as pointers to
-	  external cmdline or DTB. This however breaks in absence of uboot,
-	  when booting from Metaware debugger directly, as the registers are
-	  not zeroed out on reset by mdb and/or ARCv2 based cores. The bogus
-	  registers look like uboot args to kernel which then chokes.
-	  So only enable the uboot arg checking/processing if users are sure
-	  of uboot being in play.
-
 config ARC_BUILTIN_DTB_NAME
 	string "Built in DTB"
 	help

arch/arc/configs/nps_defconfig

@@ -31,7 +31,6 @@ CONFIG_ARC_CACHE_LINE_SHIFT=5
 # CONFIG_ARC_HAS_LLSC is not set
 CONFIG_ARC_KVADDR_SIZE=402
 CONFIG_ARC_EMUL_UNALIGNED=y
-CONFIG_ARC_UBOOT_SUPPORT=y
 CONFIG_PREEMPT=y
 CONFIG_NET=y
 CONFIG_UNIX=y

arch/arc/configs/vdk_hs38_defconfig

@@ -13,7 +13,6 @@ CONFIG_PARTITION_ADVANCED=y
 CONFIG_ARC_PLAT_AXS10X=y
 CONFIG_AXS103=y
 CONFIG_ISA_ARCV2=y
-CONFIG_ARC_UBOOT_SUPPORT=y
 CONFIG_ARC_BUILTIN_DTB_NAME="vdk_hs38"
 CONFIG_PREEMPT=y
 CONFIG_NET=y

arch/arc/configs/vdk_hs38_smp_defconfig

@@ -15,8 +15,6 @@ CONFIG_AXS103=y
 CONFIG_ISA_ARCV2=y
 CONFIG_SMP=y
 # CONFIG_ARC_TIMERS_64BIT is not set
-# CONFIG_ARC_SMP_HALT_ON_RESET is not set
-CONFIG_ARC_UBOOT_SUPPORT=y
 CONFIG_ARC_BUILTIN_DTB_NAME="vdk_hs38_smp"
 CONFIG_PREEMPT=y
 CONFIG_NET=y

arch/arc/kernel/head.S

@@ -100,7 +100,6 @@ ENTRY(stext)
 	st.ab   0, [r5, 4]
 1:
 
-#ifdef CONFIG_ARC_UBOOT_SUPPORT
 	; Uboot - kernel ABI
 	;    r0 = [0] No uboot interaction, [1] cmdline in r2, [2] DTB in r2
 	;    r1 = magic number (always zero as of now)
@@ -109,7 +108,6 @@ ENTRY(stext)
 	st	r0, [@uboot_tag]
 	st      r1, [@uboot_magic]
 	st	r2, [@uboot_arg]
-#endif
 
 	; setup "current" tsk and optionally cache it in dedicated r25
 	mov	r9, @init_task

arch/arc/kernel/setup.c

@@ -493,7 +493,6 @@ void __init handle_uboot_args(void)
 	bool use_embedded_dtb = true;
 	bool append_cmdline = false;
 
-#ifdef CONFIG_ARC_UBOOT_SUPPORT
 	/* check that we know this tag */
 	if (uboot_tag != UBOOT_TAG_NONE &&
 	    uboot_tag != UBOOT_TAG_CMDLINE &&
@@ -525,7 +524,6 @@ void __init handle_uboot_args(void)
 		append_cmdline = true;
 
 ignore_uboot_args:
-#endif
 
 	if (use_embedded_dtb) {
 		machine_desc = setup_machine_fdt(__dtb_start);

arch/arc/kernel/troubleshoot.c

@@ -179,6 +179,12 @@ void show_regs(struct pt_regs *regs)
 	struct task_struct *tsk = current;
 	struct callee_regs *cregs;
 
+	/*
+	 * generic code calls us with preemption disabled, but some calls
+	 * here could sleep, so re-enable to avoid lockdep splat
+	 */
+	preempt_enable();
+
 	print_task_path_n_nm(tsk);
 	show_regs_print_info(KERN_INFO);
 
@@ -221,6 +227,8 @@ void show_regs(struct pt_regs *regs)
 	cregs = (struct callee_regs *)current->thread.callee_reg;
 	if (cregs)
 		show_callee_regs(cregs);
+
+	preempt_disable();
 }
 
 void show_kernel_fault_diag(const char *str, struct pt_regs *regs,