Merge tag 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rmk/linux

Pull ARM updates from Russell King:

 - Updates to AMBA bus subsystem to drop .owner struct device_driver
   initialisations, moving that to code instead.

 - Add LPAE privileged-access-never support

 - Add support for Clang CFI

 - clkdev: report over-sized device or connection strings

* tag 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rmk/linux: (36 commits)
  ARM: 9398/1: Fix userspace enter on LPAE with CC_OPTIMIZE_FOR_SIZE=y
  clkdev: report over-sized strings when creating clkdev entries
  ARM: 9393/1: mm: Use conditionals for CFI branches
  ARM: 9392/2: Support CLANG CFI
  ARM: 9391/2: hw_breakpoint: Handle CFI breakpoints
  ARM: 9390/2: lib: Annotate loop delay instructions for CFI
  ARM: 9389/2: mm: Define prototypes for all per-processor calls
  ARM: 9388/2: mm: Type-annotate all per-processor assembly routines
  ARM: 9387/2: mm: Rewrite cacheflush vtables in CFI safe C
  ARM: 9386/2: mm: Use symbol alias for cache functions
  ARM: 9385/2: mm: Type-annotate all cache assembly routines
  ARM: 9384/2: mm: Make tlbflush routines CFI safe
  ARM: 9382/1: ftrace: Define ftrace_stub_graph
  ARM: 9358/2: Implement PAN for LPAE by TTBR0 page table walks disablement
  ARM: 9357/2: Reduce the number of #ifdef CONFIG_CPU_SW_DOMAIN_PAN
  ARM: 9356/2: Move asm statements accessing TTBCR into C functions
  ARM: 9355/2: Add TTBCR_* definitions to pgtable-3level-hwdef.h
  ARM: 9379/1: coresight: tpda: drop owner assignment
  ARM: 9378/1: coresight: etm4x: drop owner assignment
  ARM: 9377/1: hwrng: nomadik: drop owner assignment
  ...

1 files changed, 29 insertions, 0 deletions

diff --git a/arch/arm/mm/fault.c b/arch/arm/mm/fault.c
index 439dc6a26bb9..dfa9554ef331 100644
--- a/arch/arm/mm/fault.c
+++ b/arch/arm/mm/fault.c
@@ -242,6 +242,27 @@ static inline bool is_permission_fault(unsigned int fsr)
 	return false;
 }
 
+#ifdef CONFIG_CPU_TTBR0_PAN
+static inline bool ttbr0_usermode_access_allowed(struct pt_regs *regs)
+{
+	struct svc_pt_regs *svcregs;
+
+	/* If we are in user mode: permission granted */
+	if (user_mode(regs))
+		return true;
+
+	/* uaccess state saved above pt_regs on SVC exception entry */
+	svcregs = to_svc_pt_regs(regs);
+
+	return !(svcregs->ttbcr & TTBCR_EPD0);
+}
+#else
+static inline bool ttbr0_usermode_access_allowed(struct pt_regs *regs)
+{
+	return true;
+}
+#endif
+
 static int __kprobes
 do_page_fault(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
 {
@@ -285,6 +306,14 @@ do_page_fault(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
 
 	perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, addr);
 
+	/*
+	 * Privileged access aborts with CONFIG_CPU_TTBR0_PAN enabled are
+	 * routed via the translation fault mechanism. Check whether uaccess
+	 * is disabled while in kernel mode.
+	 */
+	if (!ttbr0_usermode_access_allowed(regs))
+		goto no_context;
+
 	if (!(flags & FAULT_FLAG_USER))
 		goto lock_mmap;