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authorLinus Torvalds <torvalds@linux-foundation.org>2020-12-18 21:43:07 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2020-12-18 21:43:07 +0300
commite2ae634014d3a8839a99f8897b3f6346a133a33b (patch)
treec33b6df0010a651f0ec890f60a7fdfd6216f7964 /lib
parenta409ed156a90093a03fe6a93721ddf4c591eac87 (diff)
parent7d95a88f9254b711a3a95106fc73f6a3a9866a40 (diff)
downloadlinux-e2ae634014d3a8839a99f8897b3f6346a133a33b.tar.xz
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
Diffstat (limited to 'lib')
-rw-r--r--lib/Kconfig3
-rw-r--r--lib/Kconfig.debug2
-rw-r--r--lib/Makefile2
-rw-r--r--lib/devmem_is_allowed.c27
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;
+}