Merge 4.4.185 into android-4.4

Changes in 4.4.185
	fs/binfmt_flat.c: make load_flat_shared_library() work
	mm/page_idle.c: fix oops because end_pfn is larger than max_pfn
	scsi: vmw_pscsi: Fix use-after-free in pvscsi_queue_lck()
	tracing: Silence GCC 9 array bounds warning
	gcc-9: silence 'address-of-packed-member' warning
	usb: chipidea: udc: workaround for endpoint conflict issue
	Input: uinput - add compat ioctl number translation for UI_*_FF_UPLOAD
	apparmor: enforce nullbyte at end of tag string
	parport: Fix mem leak in parport_register_dev_model
	parisc: Fix compiler warnings in float emulation code
	IB/hfi1: Insure freeze_work work_struct is canceled on shutdown
	MIPS: uprobes: remove set but not used variable 'epc'
	net: hns: Fix loopback test failed at copper ports
	sparc: perf: fix updated event period in response to PERF_EVENT_IOC_PERIOD
	scripts/checkstack.pl: Fix arm64 wrong or unknown architecture
	scsi: ufs: Check that space was properly alloced in copy_query_response
	s390/qeth: fix VLAN attribute in bridge_hostnotify udev event
	hwmon: (pmbus/core) Treat parameters as paged if on multiple pages
	Btrfs: fix race between readahead and device replace/removal
	btrfs: start readahead also in seed devices
	can: flexcan: fix timeout when set small bitrate
	can: purge socket error queue on sock destruct
	ARM: imx: cpuidle-imx6sx: Restrict the SW2ISO increase to i.MX6SX
	Bluetooth: Align minimum encryption key size for LE and BR/EDR connections
	Bluetooth: Fix regression with minimum encryption key size alignment
	SMB3: retry on STATUS_INSUFFICIENT_RESOURCES instead of failing write
	cfg80211: fix memory leak of wiphy device name
	mac80211: drop robust management frames from unknown TA
	perf ui helpline: Use strlcpy() as a shorter form of strncpy() + explicit set nul
	perf help: Remove needless use of strncpy()
	9p/rdma: do not disconnect on down_interruptible EAGAIN
	9p: acl: fix uninitialized iattr access
	9p/rdma: remove useless check in cm_event_handler
	9p: p9dirent_read: check network-provided name length
	net/9p: include trans_common.h to fix missing prototype warning.
	KVM: X86: Fix scan ioapic use-before-initialization
	ovl: modify ovl_permission() to do checks on two inodes
	x86/speculation: Allow guests to use SSBD even if host does not
	cpu/speculation: Warn on unsupported mitigations= parameter
	sctp: change to hold sk after auth shkey is created successfully
	tipc: change to use register_pernet_device
	tipc: check msg->req data len in tipc_nl_compat_bearer_disable
	team: Always enable vlan tx offload
	ipv4: Use return value of inet_iif() for __raw_v4_lookup in the while loop
	bonding: Always enable vlan tx offload
	net: check before dereferencing netdev_ops during busy poll
	Bluetooth: Fix faulty expression for minimum encryption key size check
	um: Compile with modern headers
	ASoC : cs4265 : readable register too low
	spi: bitbang: Fix NULL pointer dereference in spi_unregister_master
	ASoC: max98090: remove 24-bit format support if RJ is 0
	usb: gadget: fusb300_udc: Fix memory leak of fusb300->ep[i]
	usb: gadget: udc: lpc32xx: allocate descriptor with GFP_ATOMIC
	scsi: hpsa: correct ioaccel2 chaining
	ARC: Assume multiplier is always present
	ARC: fix build warning in elf.h
	MIPS: math-emu: do not use bools for arithmetic
	mfd: omap-usb-tll: Fix register offsets
	swiotlb: Make linux/swiotlb.h standalone includible
	bug.h: work around GCC PR82365 in BUG()
	MIPS: Workaround GCC __builtin_unreachable reordering bug
	ptrace: Fix ->ptracer_cred handling for PTRACE_TRACEME
	crypto: user - prevent operating on larval algorithms
	ALSA: seq: fix incorrect order of dest_client/dest_ports arguments
	ALSA: firewire-lib/fireworks: fix miss detection of received MIDI messages
	ALSA: usb-audio: fix sign unintended sign extension on left shifts
	lib/mpi: Fix karactx leak in mpi_powm
	btrfs: Ensure replaced device doesn't have pending chunk allocation
	tty: rocket: fix incorrect forward declaration of 'rp_init()'
	ARC: handle gcc generated __builtin_trap for older compiler
	arm64, vdso: Define vdso_{start,end} as array
	KVM: x86: degrade WARN to pr_warn_ratelimited
	dmaengine: imx-sdma: remove BD_INTR for channel0
	Linux 4.4.185

Change-Id: I222f9f81b9d7fba3cd3ac028b473b1ea2fae7cf0
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>

1 files changed, 35 insertions, 0 deletions

diff --git a/arch/mips/include/asm/compiler.h b/arch/mips/include/asm/compiler.h
index e081a265f422..cc2eb1b06050 100644
--- a/arch/mips/include/asm/compiler.h
+++ b/arch/mips/include/asm/compiler.h
@@ -8,6 +8,41 @@
 #ifndef _ASM_COMPILER_H
 #define _ASM_COMPILER_H
 
+/*
+ * With GCC 4.5 onwards we can use __builtin_unreachable to indicate to the
+ * compiler that a particular code path will never be hit. This allows it to be
+ * optimised out of the generated binary.
+ *
+ * Unfortunately at least GCC 4.6.3 through 7.3.0 inclusive suffer from a bug
+ * that can lead to instructions from beyond an unreachable statement being
+ * incorrectly reordered into earlier delay slots if the unreachable statement
+ * is the only content of a case in a switch statement. This can lead to
+ * seemingly random behaviour, such as invalid memory accesses from incorrectly
+ * reordered loads or stores. See this potential GCC fix for details:
+ *
+ *   https://gcc.gnu.org/ml/gcc-patches/2015-09/msg00360.html
+ *
+ * It is unclear whether GCC 8 onwards suffer from the same issue - nothing
+ * relevant is mentioned in GCC 8 release notes and nothing obviously relevant
+ * stands out in GCC commit logs, but these newer GCC versions generate very
+ * different code for the testcase which doesn't exhibit the bug.
+ *
+ * GCC also handles stack allocation suboptimally when calling noreturn
+ * functions or calling __builtin_unreachable():
+ *
+ *   https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82365
+ *
+ * We work around both of these issues by placing a volatile asm statement,
+ * which GCC is prevented from reordering past, prior to __builtin_unreachable
+ * calls.
+ *
+ * The .insn statement is required to ensure that any branches to the
+ * statement, which sadly must be kept due to the asm statement, are known to
+ * be branches to code and satisfy linker requirements for microMIPS kernels.
+ */
+#undef barrier_before_unreachable
+#define barrier_before_unreachable() asm volatile(".insn")
+
 #if __GNUC__ > 3 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4)
 #define GCC_IMM_ASM() "n"
 #define GCC_REG_ACCUM "$0"