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

Pull arm64 updates from Catalin Marinas:
 "Apart from some new arm64 features and clean-ups, this also contains
  the core mmu_gather changes for tracking the levels of the page table
  being cleared and a minor update to the generic
  compat_sys_sigaltstack() introducing COMPAT_SIGMINSKSZ.

  Summary:

   - Core mmu_gather changes which allow tracking the levels of
     page-table being cleared together with the arm64 low-level flushing
     routines

   - Support for the new ARMv8.5 PSTATE.SSBS bit which can be used to
     mitigate Spectre-v4 dynamically without trapping to EL3 firmware

   - Introduce COMPAT_SIGMINSTKSZ for use in compat_sys_sigaltstack

   - Optimise emulation of MRS instructions to ID_* registers on ARMv8.4

   - Support for Common Not Private (CnP) translations allowing threads
     of the same CPU to share the TLB entries

   - Accelerated crc32 routines

   - Move swapper_pg_dir to the rodata section

   - Trap WFI instruction executed in user space

   - ARM erratum 1188874 workaround (arch_timer)

   - Miscellaneous fixes and clean-ups"

* tag 'arm64-upstream' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux: (78 commits)
  arm64: KVM: Guests can skip __install_bp_hardening_cb()s HYP work
  arm64: cpufeature: Trap CTR_EL0 access only where it is necessary
  arm64: cpufeature: Fix handling of CTR_EL0.IDC field
  arm64: cpufeature: ctr: Fix cpu capability check for late CPUs
  Documentation/arm64: HugeTLB page implementation
  arm64: mm: Use __pa_symbol() for set_swapper_pgd()
  arm64: Add silicon-errata.txt entry for ARM erratum 1188873
  Revert "arm64: uaccess: implement unsafe accessors"
  arm64: mm: Drop the unused cpu parameter
  MAINTAINERS: fix bad sdei paths
  arm64: mm: Use #ifdef for the __PAGETABLE_P?D_FOLDED defines
  arm64: Fix typo in a comment in arch/arm64/mm/kasan_init.c
  arm64: xen: Use existing helper to check interrupt status
  arm64: Use daifflag_restore after bp_hardening
  arm64: daifflags: Use irqflags functions for daifflags
  arm64: arch_timer: avoid unused function warning
  arm64: Trap WFI executed in userspace
  arm64: docs: Document SSBS HWCAP
  arm64: docs: Fix typos in ELF hwcaps
  arm64/kprobes: remove an extra semicolon in arch_prepare_kprobe
  ...

1 files changed, 9 insertions, 5 deletions

diff --git a/kernel/signal.c b/kernel/signal.c
index 5843c541fda9..e4aad0e90882 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -3460,7 +3460,8 @@ int do_sigaction(int sig, struct k_sigaction *act, struct k_sigaction *oact)
 }
 
 static int
-do_sigaltstack (const stack_t *ss, stack_t *oss, unsigned long sp)
+do_sigaltstack (const stack_t *ss, stack_t *oss, unsigned long sp,
+		size_t min_ss_size)
 {
 	struct task_struct *t = current;
 
@@ -3490,7 +3491,7 @@ do_sigaltstack (const stack_t *ss, stack_t *oss, unsigned long sp)
 			ss_size = 0;
 			ss_sp = NULL;
 		} else {
-			if (unlikely(ss_size < MINSIGSTKSZ))
+			if (unlikely(ss_size < min_ss_size))
 				return -ENOMEM;
 		}
 
@@ -3508,7 +3509,8 @@ SYSCALL_DEFINE2(sigaltstack,const stack_t __user *,uss, stack_t __user *,uoss)
 	if (uss && copy_from_user(&new, uss, sizeof(stack_t)))
 		return -EFAULT;
 	err = do_sigaltstack(uss ? &new : NULL, uoss ? &old : NULL,
-			      current_user_stack_pointer());
+			      current_user_stack_pointer(),
+			      MINSIGSTKSZ);
 	if (!err && uoss && copy_to_user(uoss, &old, sizeof(stack_t)))
 		err = -EFAULT;
 	return err;
@@ -3519,7 +3521,8 @@ int restore_altstack(const stack_t __user *uss)
 	stack_t new;
 	if (copy_from_user(&new, uss, sizeof(stack_t)))
 		return -EFAULT;
-	(void)do_sigaltstack(&new, NULL, current_user_stack_pointer());
+	(void)do_sigaltstack(&new, NULL, current_user_stack_pointer(),
+			     MINSIGSTKSZ);
 	/* squash all but EFAULT for now */
 	return 0;
 }
@@ -3553,7 +3556,8 @@ static int do_compat_sigaltstack(const compat_stack_t __user *uss_ptr,
 		uss.ss_size = uss32.ss_size;
 	}
 	ret = do_sigaltstack(uss_ptr ? &uss : NULL, &uoss,
-			     compat_user_stack_pointer());
+			     compat_user_stack_pointer(),
+			     COMPAT_MINSIGSTKSZ);
 	if (ret >= 0 && uoss_ptr)  {
 		compat_stack_t old;
 		memset(&old, 0, sizeof(old));