Merge tag 'arm64-upstream' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux

Pull arm64 festive updates from Will Deacon:
 "In the end, we ended up with quite a lot more than I expected:

   - Support for ARMv8.3 Pointer Authentication in userspace (CRIU and
     kernel-side support to come later)

   - Support for per-thread stack canaries, pending an update to GCC
     that is currently undergoing review

   - Support for kexec_file_load(), which permits secure boot of a kexec
     payload but also happens to improve the performance of kexec
     dramatically because we can avoid the sucky purgatory code from
     userspace. Kdump will come later (requires updates to libfdt).

   - Optimisation of our dynamic CPU feature framework, so that all
     detected features are enabled via a single stop_machine()
     invocation

   - KPTI whitelisting of Cortex-A CPUs unaffected by Meltdown, so that
     they can benefit from global TLB entries when KASLR is not in use

   - 52-bit virtual addressing for userspace (kernel remains 48-bit)

   - Patch in LSE atomics for per-cpu atomic operations

   - Custom preempt.h implementation to avoid unconditional calls to
     preempt_schedule() from preempt_enable()

   - Support for the new 'SB' Speculation Barrier instruction

   - Vectorised implementation of XOR checksumming and CRC32
     optimisations

   - Workaround for Cortex-A76 erratum #1165522

   - Improved compatibility with Clang/LLD

   - Support for TX2 system PMUS for profiling the L3 cache and DMC

   - Reflect read-only permissions in the linear map by default

   - Ensure MMIO reads are ordered with subsequent calls to Xdelay()

   - Initial support for memory hotplug

   - Tweak the threshold when we invalidate the TLB by-ASID, so that
     mremap() performance is improved for ranges spanning multiple PMDs.

   - Minor refactoring and cleanups"

* tag 'arm64-upstream' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux: (125 commits)
  arm64: kaslr: print PHYS_OFFSET in dump_kernel_offset()
  arm64: sysreg: Use _BITUL() when defining register bits
  arm64: cpufeature: Rework ptr auth hwcaps using multi_entry_cap_matches
  arm64: cpufeature: Reduce number of pointer auth CPU caps from 6 to 4
  arm64: docs: document pointer authentication
  arm64: ptr auth: Move per-thread keys from thread_info to thread_struct
  arm64: enable pointer authentication
  arm64: add prctl control for resetting ptrauth keys
  arm64: perf: strip PAC when unwinding userspace
  arm64: expose user PAC bit positions via ptrace
  arm64: add basic pointer authentication support
  arm64/cpufeature: detect pointer authentication
  arm64: Don't trap host pointer auth use to EL2
  arm64/kvm: hide ptrauth from guests
  arm64/kvm: consistently handle host HCR_EL2 flags
  arm64: add pointer authentication register bits
  arm64: add comments about EC exception levels
  arm64: perf: Treat EXCLUDE_EL* bit definitions as unsigned
  arm64: kpti: Whitelist Cortex-A CPUs that don't implement the CSV3 field
  arm64: enable per-task stack canaries
  ...

1 files changed, 4 insertions, 8 deletions

diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S
index 039144ecbcb2..763f03dc4d9e 100644
--- a/arch/arm64/kernel/entry.S
+++ b/arch/arm64/kernel/entry.S
@@ -344,10 +344,6 @@ alternative_else_nop_endif
 	ldp	x28, x29, [sp, #16 * 14]
 	ldr	lr, [sp, #S_LR]
 	add	sp, sp, #S_FRAME_SIZE		// restore sp
-	/*
-	 * ARCH_HAS_MEMBARRIER_SYNC_CORE rely on eret context synchronization
-	 * when returning from IPI handler, and when returning to user-space.
-	 */
 
 	.if	\el == 0
 alternative_insn eret, nop, ARM64_UNMAP_KERNEL_AT_EL0
@@ -363,6 +359,7 @@ alternative_insn eret, nop, ARM64_UNMAP_KERNEL_AT_EL0
 	.else
 	eret
 	.endif
+	sb
 	.endm
 
 	.macro	irq_stack_entry
@@ -622,10 +619,8 @@ el1_irq:
 	irq_handler
 
 #ifdef CONFIG_PREEMPT
-	ldr	w24, [tsk, #TSK_TI_PREEMPT]	// get preempt count
-	cbnz	w24, 1f				// preempt count != 0
-	ldr	x0, [tsk, #TSK_TI_FLAGS]	// get flags
-	tbz	x0, #TIF_NEED_RESCHED, 1f	// needs rescheduling?
+	ldr	x24, [tsk, #TSK_TI_PREEMPT]	// get preempt count
+	cbnz	x24, 1f				// preempt count != 0
 	bl	el1_preempt
 1:
 #endif
@@ -1006,6 +1001,7 @@ alternative_insn isb, nop, ARM64_WORKAROUND_QCOM_FALKOR_E1003
 	mrs	x30, far_el1
 	.endif
 	eret
+	sb
 	.endm
 
 	.align	11