Merge tag 'riscv/for-v5.5-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux

Pull RISC-V updates from Paul Walmsley:
 "New features:
   - SECCOMP support
   - nommu support
   - SBI-less system support
   - M-Mode support
   - TLB flush optimizations

  Other improvements:
   - Pass the complete RISC-V ISA string supported by the CPU cores to
     userspace, rather than redacting parts of it in the kernel
   - Add platform DMA IP block data to the HiFive Unleashed board DT
     file
   - Add Makefile support for BZ2, LZ4, LZMA, LZO kernel image
     compression formats, in line with other architectures

  Cleanups:
   - Remove unnecessary PTE_PARENT_SIZE macro
   - Standardize include guard naming across arch/riscv"

* tag 'riscv/for-v5.5-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux: (22 commits)
  riscv: provide a flat image loader
  riscv: add nommu support
  riscv: clear the instruction cache and all registers when booting
  riscv: read the hart ID from mhartid on boot
  riscv: provide native clint access for M-mode
  riscv: dts: add support for PDMA device of HiFive Unleashed Rev A00
  riscv: add support for MMIO access to the timer registers
  riscv: implement remote sfence.i using IPIs
  riscv: cleanup the default power off implementation
  riscv: poison SBI calls for M-mode
  riscv: don't allow selecting SBI based drivers for M-mode
  RISC-V: Add multiple compression image format.
  riscv: clean up the macro format in each header file
  riscv: Use PMD_SIZE to replace PTE_PARENT_SIZE
  riscv: abstract out CSR names for supervisor vs machine mode
  riscv: separate MMIO functions into their own header file
  riscv: enter WFI in default_power_off() if SBI does not shutdown
  RISC-V: Issue a tlb page flush if possible
  RISC-V: Issue a local tlbflush if possible.
  RISC-V: Do not invoke SBI call if cpumask is empty
  ...

1 files changed, 41 insertions, 9 deletions

diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index 75a6c9117622..9f7f5dce2dc4 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -26,14 +26,15 @@ config RISCV
 	select GENERIC_IRQ_SHOW
 	select GENERIC_PCI_IOMAP
 	select GENERIC_SCHED_CLOCK
-	select GENERIC_STRNCPY_FROM_USER
-	select GENERIC_STRNLEN_USER
+	select GENERIC_STRNCPY_FROM_USER if MMU
+	select GENERIC_STRNLEN_USER if MMU
 	select GENERIC_SMP_IDLE_THREAD
 	select GENERIC_ATOMIC64 if !64BIT
 	select HAVE_ARCH_AUDITSYSCALL
+	select HAVE_ARCH_SECCOMP_FILTER
 	select HAVE_ASM_MODVERSIONS
 	select HAVE_MEMBLOCK_NODE_MAP
-	select HAVE_DMA_CONTIGUOUS
+	select HAVE_DMA_CONTIGUOUS if MMU
 	select HAVE_FUTEX_CMPXCHG if FUTEX
 	select HAVE_PERF_EVENTS
 	select HAVE_PERF_REGS
@@ -50,6 +51,7 @@ config RISCV
 	select PCI_DOMAINS_GENERIC if PCI
 	select PCI_MSI if PCI
 	select RISCV_TIMER
+	select UACCESS_MEMCPY if !MMU
 	select GENERIC_IRQ_MULTI_HANDLER
 	select GENERIC_ARCH_TOPOLOGY if SMP
 	select ARCH_HAS_PTE_SPECIAL
@@ -60,7 +62,7 @@ config RISCV
 	select ARCH_WANT_HUGE_PMD_SHARE if 64BIT
 	select SPARSEMEM_STATIC if 32BIT
 	select ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT if MMU
-	select HAVE_ARCH_MMAP_RND_BITS
+	select HAVE_ARCH_MMAP_RND_BITS if MMU
 
 config ARCH_MMAP_RND_BITS_MIN
 	default 18 if 64BIT
@@ -72,8 +74,23 @@ config ARCH_MMAP_RND_BITS_MAX
 	default 24 if 64BIT # SV39 based
 	default 17
 
+# set if we run in machine mode, cleared if we run in supervisor mode
+config RISCV_M_MODE
+	bool
+	default !MMU
+
+# set if we are running in S-mode and can use SBI calls
+config RISCV_SBI
+	bool
+	depends on !RISCV_M_MODE
+	default y
+
 config MMU
-	def_bool y
+	bool "MMU-based Paged Memory Management Support"
+	default y
+	help
+	  Select if you want MMU-based virtualised addressing space
+	  support by paged memory management. If unsure, say 'Y'.
 
 config ZONE_DMA32
 	bool
@@ -92,6 +109,7 @@ config PA_BITS
 config PAGE_OFFSET
 	hex
 	default 0xC0000000 if 32BIT && MAXPHYSMEM_2GB
+	default 0x80000000 if 64BIT && !MMU
 	default 0xffffffff80000000 if 64BIT && MAXPHYSMEM_2GB
 	default 0xffffffe000000000 if 64BIT && MAXPHYSMEM_128GB
 
@@ -135,7 +153,7 @@ config GENERIC_HWEIGHT
 	def_bool y
 
 config FIX_EARLYCON_MEM
-	def_bool y
+	def_bool CONFIG_MMU
 
 config PGTABLE_LEVELS
 	int
@@ -160,6 +178,7 @@ config ARCH_RV32I
 	select GENERIC_LIB_ASHRDI3
 	select GENERIC_LIB_LSHRDI3
 	select GENERIC_LIB_UCMPDI2
+	select MMU
 
 config ARCH_RV64I
 	bool "RV64I"
@@ -168,9 +187,9 @@ config ARCH_RV64I
 	select HAVE_FUNCTION_TRACER
 	select HAVE_FUNCTION_GRAPH_TRACER
 	select HAVE_FTRACE_MCOUNT_RECORD
-	select HAVE_DYNAMIC_FTRACE
-	select HAVE_DYNAMIC_FTRACE_WITH_REGS
-	select SWIOTLB
+	select HAVE_DYNAMIC_FTRACE if MMU
+	select HAVE_DYNAMIC_FTRACE_WITH_REGS if HAVE_DYNAMIC_FTRACE
+	select SWIOTLB if MMU
 
 endchoice
 
@@ -272,6 +291,19 @@ menu "Kernel features"
 
 source "kernel/Kconfig.hz"
 
+config SECCOMP
+	bool "Enable seccomp to safely compute untrusted bytecode"
+	help
+	  This kernel feature is useful for number crunching applications
+	  that may need to compute untrusted bytecode during their
+	  execution. By using pipes or other transports made available to
+	  the process as file descriptors supporting the read/write
+	  syscalls, it's possible to isolate those applications in
+	  their own address space using seccomp. Once seccomp is
+	  enabled via prctl(PR_SET_SECCOMP), it cannot be disabled
+	  and the task is only allowed to execute a few safe syscalls
+	  defined by each seccomp mode.
+
 endmenu
 
 menu "Boot options"