Merge tag 'riscv-for-linus-5.11-mw0' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux

Pull RISC-V updates from Palmer Dabbelt:
 "We have a handful of new kernel features for 5.11:

   - Support for the contiguous memory allocator.

   - Support for IRQ Time Accounting

   - Support for stack tracing

   - Support for strict /dev/mem

   - Support for kernel section protection

  I'm being a bit conservative on the cutoff for this round due to the
  timing, so this is all the new development I'm going to take for this
  cycle (even if some of it probably normally would have been OK). There
  are, however, some fixes on the list that I will likely be sending
  along either later this week or early next week.

  There is one issue in here: one of my test configurations
  (PREEMPT{,_DEBUG}=y) fails to boot on QEMU 5.0.0 (from April) as of
  the .text.init alignment patch.

  With any luck we'll sort out the issue, but given how many bugs get
  fixed all over the place and how unrelated those features seem my
  guess is that we're just running into something that's been lurking
  for a while and has already been fixed in the newer QEMU (though I
  wouldn't be surprised if it's one of these implicit assumptions we
  have in the boot flow). If it was hardware I'd be strongly inclined to
  look more closely, but given that users can upgrade their simulators
  I'm less worried about it"

* tag 'riscv-for-linus-5.11-mw0' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux:
  arm64: Use the generic devmem_is_allowed()
  arm: Use the generic devmem_is_allowed()
  RISC-V: Use the new generic devmem_is_allowed()
  lib: Add a generic version of devmem_is_allowed()
  riscv: Fixed kernel test robot warning
  riscv: kernel: Drop unused clean rule
  riscv: provide memmove implementation
  RISC-V: Move dynamic relocation section under __init
  RISC-V: Protect all kernel sections including init early
  RISC-V: Align the .init.text section
  RISC-V: Initialize SBI early
  riscv: Enable ARCH_STACKWALK
  riscv: Make stack walk callback consistent with generic code
  riscv: Cleanup stacktrace
  riscv: Add HAVE_IRQ_TIME_ACCOUNTING
  riscv: Enable CMA support
  riscv: Ignore Image.* and loader.bin
  riscv: Clean up boot dir
  riscv: Fix compressed Image formats build
  RISC-V: Add kernel image sections to the resource tree

4 files changed, 33 insertions, 1 deletions

diff --git a/lib/Kconfig b/lib/Kconfig
index b46a9fd122c8..46806332a8cc 100644
--- a/lib/Kconfig
+++ b/lib/Kconfig
@@ -686,6 +686,9 @@ config GENERIC_LIB_CMPDI2
 config GENERIC_LIB_UCMPDI2
 	bool
 
+config GENERIC_LIB_DEVMEM_IS_ALLOWED
+	bool
+
 config PLDMFW
 	bool
 	default n
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index 7d7097c5dc58..e6e58b26e888 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -1676,7 +1676,7 @@ config ARCH_HAS_DEVMEM_IS_ALLOWED
 config STRICT_DEVMEM
 	bool "Filter access to /dev/mem"
 	depends on MMU && DEVMEM
-	depends on ARCH_HAS_DEVMEM_IS_ALLOWED
+	depends on ARCH_HAS_DEVMEM_IS_ALLOWED || GENERIC_LIB_DEVMEM_IS_ALLOWED
 	default y if PPC || X86 || ARM64
 	help
 	  If this option is disabled, you allow userspace (root) access to all
diff --git a/lib/Makefile b/lib/Makefile
index 8598e8796edf..afeff05fa8c5 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -354,3 +354,5 @@ obj-$(CONFIG_LIST_KUNIT_TEST) += list-test.o
 obj-$(CONFIG_LINEAR_RANGES_TEST) += test_linear_ranges.o
 obj-$(CONFIG_BITS_TEST) += test_bits.o
 obj-$(CONFIG_CMDLINE_KUNIT_TEST) += cmdline_kunit.o
+
+obj-$(CONFIG_GENERIC_LIB_DEVMEM_IS_ALLOWED) += devmem_is_allowed.o
diff --git a/lib/devmem_is_allowed.c b/lib/devmem_is_allowed.c
new file mode 100644
index 000000000000..c0d67c541849
--- /dev/null
+++ b/lib/devmem_is_allowed.c
@@ -0,0 +1,27 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * A generic version of devmem_is_allowed.
+ *
+ * Based on arch/arm64/mm/mmap.c
+ *
+ * Copyright (C) 2020 Google, Inc.
+ * Copyright (C) 2012 ARM Ltd.
+ */
+
+#include <linux/mm.h>
+#include <linux/ioport.h>
+
+/*
+ * devmem_is_allowed() checks to see if /dev/mem access to a certain address
+ * is valid. The argument is a physical page number.  We mimic x86 here by
+ * disallowing access to system RAM as well as device-exclusive MMIO regions.
+ * This effectively disable read()/write() on /dev/mem.
+ */
+int devmem_is_allowed(unsigned long pfn)
+{
+	if (iomem_is_exclusive(pfn << PAGE_SHIFT))
+		return 0;
+	if (!page_is_ram(pfn))
+		return 1;
+	return 0;
+}