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linux/arch/riscv/Kconfig
Linus Torvalds 9471f1f2f5 Merge branch 'expand-stack' 
This modifies our user mode stack expansion code to always take the
mmap_lock for writing before modifying the VM layout.

It's actually something we always technically should have done, but
because we didn't strictly need it, we were being lazy ("opportunistic"
sounds so much better, doesn't it?) about things, and had this hack in
place where we would extend the stack vma in-place without doing the
proper locking.

And it worked fine.  We just needed to change vm_start (or, in the case
of grow-up stacks, vm_end) and together with some special ad-hoc locking
using the anon_vma lock and the mm->page_table_lock, it all was fairly
straightforward.

That is, it was all fine until Ruihan Li pointed out that now that the
vma layout uses the maple tree code, we *really* don't just change
vm_start and vm_end any more, and the locking really is broken.  Oops.

It's not actually all _that_ horrible to fix this once and for all, and
do proper locking, but it's a bit painful.  We have basically three
different cases of stack expansion, and they all work just a bit
differently:

 - the common and obvious case is the page fault handling. It's actually
   fairly simple and straightforward, except for the fact that we have
   something like 24 different versions of it, and you end up in a maze
   of twisty little passages, all alike.

 - the simplest case is the execve() code that creates a new stack.
   There are no real locking concerns because it's all in a private new
   VM that hasn't been exposed to anybody, but lockdep still can end up
   unhappy if you get it wrong.

 - and finally, we have GUP and page pinning, which shouldn't really be
   expanding the stack in the first place, but in addition to execve()
   we also use it for ptrace(). And debuggers do want to possibly access
   memory under the stack pointer and thus need to be able to expand the
   stack as a special case.

None of these cases are exactly complicated, but the page fault case in
particular is just repeated slightly differently many many times.  And
ia64 in particular has a fairly complicated situation where you can have
both a regular grow-down stack _and_ a special grow-up stack for the
register backing store.

So to make this slightly more manageable, the bulk of this series is to
first create a helper function for the most common page fault case, and
convert all the straightforward architectures to it.

Thus the new 'lock_mm_and_find_vma()' helper function, which ends up
being used by x86, arm, powerpc, mips, riscv, alpha, arc, csky, hexagon,
loongarch, nios2, sh, sparc32, and xtensa.  So we not only convert more
than half the architectures, we now have more shared code and avoid some
of those twisty little passages.

And largely due to this common helper function, the full diffstat of
this series ends up deleting more lines than it adds.

That still leaves eight architectures (ia64, m68k, microblaze, openrisc,
parisc, s390, sparc64 and um) that end up doing 'expand_stack()'
manually because they are doing something slightly different from the
normal pattern.  Along with the couple of special cases in execve() and
GUP.

So there's a couple of patches that first create 'locked' helper
versions of the stack expansion functions, so that there's a obvious
path forward in the conversion.  The execve() case is then actually
pretty simple, and is a nice cleanup from our old "grow-up stackls are
special, because at execve time even they grow down".

The #ifdef CONFIG_STACK_GROWSUP in that code just goes away, because
it's just more straightforward to write out the stack expansion there
manually, instead od having get_user_pages_remote() do it for us in some
situations but not others and have to worry about locking rules for GUP.

And the final step is then to just convert the remaining odd cases to a
new world order where 'expand_stack()' is called with the mmap_lock held
for reading, but where it might drop it and upgrade it to a write, only
to return with it held for reading (in the success case) or with it
completely dropped (in the failure case).

In the process, we remove all the stack expansion from GUP (where
dropping the lock wouldn't be ok without special rules anyway), and add
it in manually to __access_remote_vm() for ptrace().

Thanks to Adrian Glaubitz and Frank Scheiner who tested the ia64 cases.
Everything else here felt pretty straightforward, but the ia64 rules for
stack expansion are really quite odd and very different from everything
else.  Also thanks to Vegard Nossum who caught me getting one of those
odd conditions entirely the wrong way around.

Anyway, I think I want to actually move all the stack expansion code to
a whole new file of its own, rather than have it split up between
mm/mmap.c and mm/memory.c, but since this will have to be backported to
the initial maple tree vma introduction anyway, I tried to keep the
patches _fairly_ minimal.

Also, while I don't think it's valid to expand the stack from GUP, the
final patch in here is a "warn if some crazy GUP user wants to try to
expand the stack" patch.  That one will be reverted before the final
release, but it's left to catch any odd cases during the merge window
and release candidates.

Reported-by: Ruihan Li <lrh2000@pku.edu.cn>

* branch 'expand-stack':
  gup: add warning if some caller would seem to want stack expansion
  mm: always expand the stack with the mmap write lock held
  execve: expand new process stack manually ahead of time
  mm: make find_extend_vma() fail if write lock not held
  powerpc/mm: convert coprocessor fault to lock_mm_and_find_vma()
  mm/fault: convert remaining simple cases to lock_mm_and_find_vma()
  arm/mm: Convert to using lock_mm_and_find_vma()
  riscv/mm: Convert to using lock_mm_and_find_vma()
  mips/mm: Convert to using lock_mm_and_find_vma()
  powerpc/mm: Convert to using lock_mm_and_find_vma()
  arm64/mm: Convert to using lock_mm_and_find_vma()
  mm: make the page fault mmap locking killable
  mm: introduce new 'lock_mm_and_find_vma()' page fault helper
2023-06-28 20:35:21 -07:00

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# SPDX-License-Identifier: GPL-2.0-only
#
# For a description of the syntax of this configuration file,
# see Documentation/kbuild/kconfig-language.rst.
#
config 64BIT
bool
config 32BIT
bool
config RISCV
def_bool y
select ARCH_DMA_DEFAULT_COHERENT
select ARCH_ENABLE_HUGEPAGE_MIGRATION if HUGETLB_PAGE && MIGRATION
select ARCH_ENABLE_SPLIT_PMD_PTLOCK if PGTABLE_LEVELS > 2
select ARCH_ENABLE_THP_MIGRATION if TRANSPARENT_HUGEPAGE
select ARCH_HAS_BINFMT_FLAT
select ARCH_HAS_CURRENT_STACK_POINTER
select ARCH_HAS_DEBUG_VIRTUAL if MMU
select ARCH_HAS_DEBUG_VM_PGTABLE
select ARCH_HAS_DEBUG_WX
select ARCH_HAS_FORTIFY_SOURCE
select ARCH_HAS_GCOV_PROFILE_ALL
select ARCH_HAS_GIGANTIC_PAGE
select ARCH_HAS_KCOV
select ARCH_HAS_MMIOWB
select ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
select ARCH_HAS_PMEM_API
select ARCH_HAS_PTE_SPECIAL
select ARCH_HAS_SET_DIRECT_MAP if MMU
select ARCH_HAS_SET_MEMORY if MMU
select ARCH_HAS_STRICT_KERNEL_RWX if MMU && !XIP_KERNEL
select ARCH_HAS_STRICT_MODULE_RWX if MMU && !XIP_KERNEL
select ARCH_HAS_TICK_BROADCAST if GENERIC_CLOCKEVENTS_BROADCAST
select ARCH_HAS_UBSAN_SANITIZE_ALL
select ARCH_HAS_VDSO_DATA
select ARCH_OPTIONAL_KERNEL_RWX if ARCH_HAS_STRICT_KERNEL_RWX
select ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
select ARCH_STACKWALK
select ARCH_SUPPORTS_ATOMIC_RMW
select ARCH_SUPPORTS_DEBUG_PAGEALLOC if MMU
select ARCH_SUPPORTS_HUGETLBFS if MMU
select ARCH_SUPPORTS_PAGE_TABLE_CHECK if MMU
select ARCH_USE_MEMTEST
select ARCH_USE_QUEUED_RWLOCKS
select ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT if MMU
select ARCH_WANT_FRAME_POINTERS
select ARCH_WANT_GENERAL_HUGETLB if !RISCV_ISA_SVNAPOT
select ARCH_WANT_HUGE_PMD_SHARE if 64BIT
select ARCH_WANT_LD_ORPHAN_WARN if !XIP_KERNEL
select ARCH_WANT_OPTIMIZE_VMEMMAP
select ARCH_WANTS_THP_SWAP if HAVE_ARCH_TRANSPARENT_HUGEPAGE
select BINFMT_FLAT_NO_DATA_START_OFFSET if !MMU
select BUILDTIME_TABLE_SORT if MMU
select CLINT_TIMER if !MMU
select CLONE_BACKWARDS
select COMMON_CLK
select CPU_PM if CPU_IDLE || HIBERNATION
select EDAC_SUPPORT
select GENERIC_ARCH_TOPOLOGY
select GENERIC_ATOMIC64 if !64BIT
select GENERIC_CLOCKEVENTS_BROADCAST if SMP
select GENERIC_EARLY_IOREMAP
select GENERIC_ENTRY
select GENERIC_GETTIMEOFDAY if HAVE_GENERIC_VDSO
select GENERIC_IDLE_POLL_SETUP
select GENERIC_IOREMAP if MMU
select GENERIC_IRQ_IPI if SMP
select GENERIC_IRQ_IPI_MUX if SMP
select GENERIC_IRQ_MULTI_HANDLER
select GENERIC_IRQ_SHOW
select GENERIC_IRQ_SHOW_LEVEL
select GENERIC_LIB_DEVMEM_IS_ALLOWED
select GENERIC_PCI_IOMAP
select GENERIC_PTDUMP if MMU
select GENERIC_SCHED_CLOCK
select GENERIC_SMP_IDLE_THREAD
select GENERIC_TIME_VSYSCALL if MMU && 64BIT
select GENERIC_VDSO_TIME_NS if HAVE_GENERIC_VDSO
select HARDIRQS_SW_RESEND
select HAS_IOPORT if MMU
select HAVE_ARCH_AUDITSYSCALL
select HAVE_ARCH_HUGE_VMALLOC if HAVE_ARCH_HUGE_VMAP
select HAVE_ARCH_HUGE_VMAP if MMU && 64BIT && !XIP_KERNEL
select HAVE_ARCH_JUMP_LABEL if !XIP_KERNEL
select HAVE_ARCH_JUMP_LABEL_RELATIVE if !XIP_KERNEL
select HAVE_ARCH_KASAN if MMU && 64BIT
select HAVE_ARCH_KASAN_VMALLOC if MMU && 64BIT
select HAVE_ARCH_KFENCE if MMU && 64BIT
select HAVE_ARCH_KGDB if !XIP_KERNEL
select HAVE_ARCH_KGDB_QXFER_PKT
select HAVE_ARCH_MMAP_RND_BITS if MMU
select HAVE_ARCH_MMAP_RND_COMPAT_BITS if COMPAT
select HAVE_ARCH_SECCOMP_FILTER
select HAVE_ARCH_THREAD_STRUCT_WHITELIST
select HAVE_ARCH_TRACEHOOK
select HAVE_ARCH_TRANSPARENT_HUGEPAGE if 64BIT && MMU
select HAVE_ARCH_VMAP_STACK if MMU && 64BIT
select HAVE_ASM_MODVERSIONS
select HAVE_CONTEXT_TRACKING_USER
select HAVE_DEBUG_KMEMLEAK
select HAVE_DMA_CONTIGUOUS if MMU
select HAVE_EBPF_JIT if MMU
select HAVE_FUNCTION_ARG_ACCESS_API
select HAVE_FUNCTION_ERROR_INJECTION
select HAVE_GCC_PLUGINS
select HAVE_GENERIC_VDSO if MMU && 64BIT
select HAVE_IRQ_TIME_ACCOUNTING
select HAVE_KPROBES if !XIP_KERNEL
select HAVE_KPROBES_ON_FTRACE if !XIP_KERNEL
select HAVE_KRETPROBES if !XIP_KERNEL
select HAVE_RETHOOK if !XIP_KERNEL
select HAVE_MOVE_PMD
select HAVE_MOVE_PUD
select HAVE_PCI
select HAVE_PERF_EVENTS
select HAVE_PERF_REGS
select HAVE_PERF_USER_STACK_DUMP
select HAVE_POSIX_CPU_TIMERS_TASK_WORK
select HAVE_REGS_AND_STACK_ACCESS_API
select HAVE_RSEQ
select HAVE_STACKPROTECTOR
select HAVE_SYSCALL_TRACEPOINTS
select HOTPLUG_CORE_SYNC_DEAD if HOTPLUG_CPU
select IRQ_DOMAIN
select IRQ_FORCED_THREADING
select KASAN_VMALLOC if KASAN
select LOCK_MM_AND_FIND_VMA
select MODULES_USE_ELF_RELA if MODULES
select MODULE_SECTIONS if MODULES
select OF
select OF_EARLY_FLATTREE
select OF_IRQ
select PCI_DOMAINS_GENERIC if PCI
select PCI_MSI if PCI
select RISCV_ALTERNATIVE if !XIP_KERNEL
select RISCV_INTC
select RISCV_TIMER if RISCV_SBI
select SIFIVE_PLIC
select SPARSE_IRQ
select SYSCTL_EXCEPTION_TRACE
select THREAD_INFO_IN_TASK
select TRACE_IRQFLAGS_SUPPORT
select UACCESS_MEMCPY if !MMU
select ZONE_DMA32 if 64BIT
select HAVE_DYNAMIC_FTRACE if !XIP_KERNEL && MMU && (CLANG_SUPPORTS_DYNAMIC_FTRACE || GCC_SUPPORTS_DYNAMIC_FTRACE)
select HAVE_DYNAMIC_FTRACE_WITH_REGS if HAVE_DYNAMIC_FTRACE
select HAVE_FTRACE_MCOUNT_RECORD if !XIP_KERNEL
select HAVE_FUNCTION_GRAPH_TRACER
select HAVE_FUNCTION_TRACER if !XIP_KERNEL && !PREEMPTION
config CLANG_SUPPORTS_DYNAMIC_FTRACE
def_bool CC_IS_CLANG
# https://github.com/llvm/llvm-project/commit/6ab8927931851bb42b2c93a00801dc499d7d9b1e
depends on CLANG_VERSION >= 130000
# https://github.com/ClangBuiltLinux/linux/issues/1817
depends on AS_IS_GNU || (AS_IS_LLVM && (LD_IS_LLD || LD_VERSION >= 23600))
config GCC_SUPPORTS_DYNAMIC_FTRACE
def_bool CC_IS_GCC
depends on $(cc-option,-fpatchable-function-entry=8)
config ARCH_MMAP_RND_BITS_MIN
default 18 if 64BIT
default 8
config ARCH_MMAP_RND_COMPAT_BITS_MIN
default 8
# max bits determined by the following formula:
# VA_BITS - PAGE_SHIFT - 3
config ARCH_MMAP_RND_BITS_MAX
default 24 if 64BIT # SV39 based
default 17
config ARCH_MMAP_RND_COMPAT_BITS_MAX
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
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 PAGE_OFFSET
hex
default 0xC0000000 if 32BIT && MMU
default 0x80000000 if !MMU
default 0xff60000000000000 if 64BIT
config KASAN_SHADOW_OFFSET
hex
depends on KASAN_GENERIC
default 0xdfffffff00000000 if 64BIT
default 0xffffffff if 32BIT
config ARCH_FLATMEM_ENABLE
def_bool !NUMA
config ARCH_SPARSEMEM_ENABLE
def_bool y
depends on MMU
select SPARSEMEM_STATIC if 32BIT && SPARSEMEM
select SPARSEMEM_VMEMMAP_ENABLE if 64BIT
config ARCH_SELECT_MEMORY_MODEL
def_bool ARCH_SPARSEMEM_ENABLE
config ARCH_SUPPORTS_UPROBES
def_bool y
config STACKTRACE_SUPPORT
def_bool y
config GENERIC_BUG
def_bool y
depends on BUG
select GENERIC_BUG_RELATIVE_POINTERS if 64BIT
config GENERIC_BUG_RELATIVE_POINTERS
bool
config GENERIC_CALIBRATE_DELAY
def_bool y
config GENERIC_CSUM
def_bool y
config GENERIC_HWEIGHT
def_bool y
config FIX_EARLYCON_MEM
def_bool MMU
config PGTABLE_LEVELS
int
default 5 if 64BIT
default 2
config LOCKDEP_SUPPORT
def_bool y
config RISCV_DMA_NONCOHERENT
bool
select ARCH_HAS_DMA_PREP_COHERENT
select ARCH_HAS_SETUP_DMA_OPS
select ARCH_HAS_SYNC_DMA_FOR_CPU
select ARCH_HAS_SYNC_DMA_FOR_DEVICE
select DMA_DIRECT_REMAP
config AS_HAS_INSN
def_bool $(as-instr,.insn r 51$(comma) 0$(comma) 0$(comma) t0$(comma) t0$(comma) zero)
source "arch/riscv/Kconfig.socs"
source "arch/riscv/Kconfig.errata"
menu "Platform type"
config NONPORTABLE
bool "Allow configurations that result in non-portable kernels"
help
RISC-V kernel binaries are compatible between all known systems
whenever possible, but there are some use cases that can only be
satisfied by configurations that result in kernel binaries that are
not portable between systems.
Selecting N does not guarantee kernels will be portable to all known
systems. Selecting any of the options guarded by NONPORTABLE will
result in kernel binaries that are unlikely to be portable between
systems.
If unsure, say N.
choice
prompt "Base ISA"
default ARCH_RV64I
help
This selects the base ISA that this kernel will target and must match
the target platform.
config ARCH_RV32I
bool "RV32I"
depends on NONPORTABLE
select 32BIT
select GENERIC_LIB_ASHLDI3
select GENERIC_LIB_ASHRDI3
select GENERIC_LIB_LSHRDI3
select GENERIC_LIB_UCMPDI2
config ARCH_RV64I
bool "RV64I"
select 64BIT
select ARCH_SUPPORTS_INT128 if CC_HAS_INT128
select SWIOTLB if MMU
endchoice
# We must be able to map all physical memory into the kernel, but the compiler
# is still a bit more efficient when generating code if it's setup in a manner
# such that it can only map 2GiB of memory.
choice
prompt "Kernel Code Model"
default CMODEL_MEDLOW if 32BIT
default CMODEL_MEDANY if 64BIT
config CMODEL_MEDLOW
bool "medium low code model"
config CMODEL_MEDANY
bool "medium any code model"
endchoice
config MODULE_SECTIONS
bool
select HAVE_MOD_ARCH_SPECIFIC
config SMP
bool "Symmetric Multi-Processing"
help
This enables support for systems with more than one CPU. If
you say N here, the kernel will run on single and
multiprocessor machines, but will use only one CPU of a
multiprocessor machine. If you say Y here, the kernel will run
on many, but not all, single processor machines. On a single
processor machine, the kernel will run faster if you say N
here.
If you don't know what to do here, say N.
config SCHED_MC
bool "Multi-core scheduler support"
depends on SMP
help
Multi-core scheduler support improves the CPU scheduler's decision
making when dealing with multi-core CPU chips at a cost of slightly
increased overhead in some places. If unsure say N here.
config NR_CPUS
int "Maximum number of CPUs (2-512)"
depends on SMP
range 2 512 if !RISCV_SBI_V01
range 2 32 if RISCV_SBI_V01 && 32BIT
range 2 64 if RISCV_SBI_V01 && 64BIT
default "32" if 32BIT
default "64" if 64BIT
config HOTPLUG_CPU
bool "Support for hot-pluggable CPUs"
depends on SMP
select GENERIC_IRQ_MIGRATION
help
Say Y here to experiment with turning CPUs off and on. CPUs
can be controlled through /sys/devices/system/cpu.
Say N if you want to disable CPU hotplug.
choice
prompt "CPU Tuning"
default TUNE_GENERIC
config TUNE_GENERIC
bool "generic"
endchoice
# Common NUMA Features
config NUMA
bool "NUMA Memory Allocation and Scheduler Support"
depends on SMP && MMU
select ARCH_SUPPORTS_NUMA_BALANCING
select GENERIC_ARCH_NUMA
select NEED_PER_CPU_EMBED_FIRST_CHUNK
select OF_NUMA
select USE_PERCPU_NUMA_NODE_ID
help
Enable NUMA (Non-Uniform Memory Access) support.
The kernel will try to allocate memory used by a CPU on the
local memory of the CPU and add some more NUMA awareness to the kernel.
config NODES_SHIFT
int "Maximum NUMA Nodes (as a power of 2)"
range 1 10
default "2"
depends on NUMA
help
Specify the maximum number of NUMA Nodes available on the target
system. Increases memory reserved to accommodate various tables.
config RISCV_ALTERNATIVE
bool
depends on !XIP_KERNEL
help
This Kconfig allows the kernel to automatically patch the
erratum or cpufeature required by the execution platform at run
time. The code patching overhead is minimal, as it's only done
once at boot and once on each module load.
config RISCV_ALTERNATIVE_EARLY
bool
depends on RISCV_ALTERNATIVE
help
Allows early patching of the kernel for special errata
config RISCV_ISA_C
bool "Emit compressed instructions when building Linux"
default y
help
Adds "C" to the ISA subsets that the toolchain is allowed to emit
when building Linux, which results in compressed instructions in the
Linux binary.
If you don't know what to do here, say Y.
config RISCV_ISA_SVNAPOT
bool "Svnapot extension support for supervisor mode NAPOT pages"
depends on 64BIT && MMU
depends on RISCV_ALTERNATIVE
default y
help
Allow kernel to detect the Svnapot ISA-extension dynamically at boot
time and enable its usage.
The Svnapot extension is used to mark contiguous PTEs as a range
of contiguous virtual-to-physical translations for a naturally
aligned power-of-2 (NAPOT) granularity larger than the base 4KB page
size. When HUGETLBFS is also selected this option unconditionally
allocates some memory for each NAPOT page size supported by the kernel.
When optimizing for low memory consumption and for platforms without
the Svnapot extension, it may be better to say N here.
If you don't know what to do here, say Y.
config RISCV_ISA_SVPBMT
bool "Svpbmt extension support for supervisor mode page-based memory types"
depends on 64BIT && MMU
depends on RISCV_ALTERNATIVE
default y
help
Adds support to dynamically detect the presence of the Svpbmt
ISA-extension (Supervisor-mode: page-based memory types) and
enable its usage.
The memory type for a page contains a combination of attributes
that indicate the cacheability, idempotency, and ordering
properties for access to that page.
The Svpbmt extension is only available on 64-bit cpus.
If you don't know what to do here, say Y.
config TOOLCHAIN_HAS_ZBB
bool
default y
depends on !64BIT || $(cc-option,-mabi=lp64 -march=rv64ima_zbb)
depends on !32BIT || $(cc-option,-mabi=ilp32 -march=rv32ima_zbb)
depends on LLD_VERSION >= 150000 || LD_VERSION >= 23900
depends on AS_IS_GNU
config RISCV_ISA_ZBB
bool "Zbb extension support for bit manipulation instructions"
depends on TOOLCHAIN_HAS_ZBB
depends on MMU
depends on RISCV_ALTERNATIVE
default y
help
Adds support to dynamically detect the presence of the ZBB
extension (basic bit manipulation) and enable its usage.
The Zbb extension provides instructions to accelerate a number
of bit-specific operations (count bit population, sign extending,
bitrotation, etc).
If you don't know what to do here, say Y.
config RISCV_ISA_ZICBOM
bool "Zicbom extension support for non-coherent DMA operation"
depends on MMU
depends on RISCV_ALTERNATIVE
default y
select RISCV_DMA_NONCOHERENT
help
Adds support to dynamically detect the presence of the ZICBOM
extension (Cache Block Management Operations) and enable its
usage.
The Zicbom extension can be used to handle for example
non-coherent DMA support on devices that need it.
If you don't know what to do here, say Y.
config RISCV_ISA_ZICBOZ
bool "Zicboz extension support for faster zeroing of memory"
depends on MMU
depends on RISCV_ALTERNATIVE
default y
help
Enable the use of the Zicboz extension (cbo.zero instruction)
when available.
The Zicboz extension is used for faster zeroing of memory.
If you don't know what to do here, say Y.
config TOOLCHAIN_HAS_ZIHINTPAUSE
bool
default y
depends on !64BIT || $(cc-option,-mabi=lp64 -march=rv64ima_zihintpause)
depends on !32BIT || $(cc-option,-mabi=ilp32 -march=rv32ima_zihintpause)
depends on LLD_VERSION >= 150000 || LD_VERSION >= 23600
config TOOLCHAIN_NEEDS_EXPLICIT_ZICSR_ZIFENCEI
def_bool y
# https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=aed44286efa8ae8717a77d94b51ac3614e2ca6dc
depends on AS_IS_GNU && AS_VERSION >= 23800
help
Newer binutils versions default to ISA spec version 20191213 which
moves some instructions from the I extension to the Zicsr and Zifencei
extensions.
config TOOLCHAIN_NEEDS_OLD_ISA_SPEC
def_bool y
depends on TOOLCHAIN_NEEDS_EXPLICIT_ZICSR_ZIFENCEI
# https://github.com/llvm/llvm-project/commit/22e199e6afb1263c943c0c0d4498694e15bf8a16
depends on CC_IS_CLANG && CLANG_VERSION < 170000
help
Certain versions of clang do not support zicsr and zifencei via -march
but newer versions of binutils require it for the reasons noted in the
help text of CONFIG_TOOLCHAIN_NEEDS_EXPLICIT_ZICSR_ZIFENCEI. This
option causes an older ISA spec compatible with these older versions
of clang to be passed to GAS, which has the same result as passing zicsr
and zifencei to -march.
config FPU
bool "FPU support"
default y
help
Say N here if you want to disable all floating-point related procedure
in the kernel.
If you don't know what to do here, say Y.
endmenu # "Platform type"
menu "Kernel features"
source "kernel/Kconfig.hz"
config RISCV_SBI_V01
bool "SBI v0.1 support"
depends on RISCV_SBI
help
This config allows kernel to use SBI v0.1 APIs. This will be
deprecated in future once legacy M-mode software are no longer in use.
config RISCV_BOOT_SPINWAIT
bool "Spinwait booting method"
depends on SMP
default y if RISCV_SBI_V01 || RISCV_M_MODE
help
This enables support for booting Linux via spinwait method. In the
spinwait method, all cores randomly jump to Linux. One of the cores
gets chosen via lottery and all other keep spinning on a percpu
variable. This method cannot support CPU hotplug and sparse hartid
scheme. It should be only enabled for M-mode Linux or platforms relying
on older firmware without SBI HSM extension. All other platforms should
rely on ordered booting via SBI HSM extension which gets chosen
dynamically at runtime if the firmware supports it.
Since spinwait is incompatible with sparse hart IDs, it requires
NR_CPUS be large enough to contain the physical hart ID of the first
hart to enter Linux.
If unsure what to do here, say N.
config KEXEC
bool "Kexec system call"
depends on MMU
select HOTPLUG_CPU if SMP
select KEXEC_CORE
help
kexec is a system call that implements the ability to shutdown your
current kernel, and to start another kernel. It is like a reboot
but it is independent of the system firmware. And like a reboot
you can start any kernel with it, not just Linux.
The name comes from the similarity to the exec system call.
config KEXEC_FILE
bool "kexec file based systmem call"
depends on 64BIT && MMU
select HAVE_IMA_KEXEC if IMA
select KEXEC_CORE
select KEXEC_ELF
help
This is new version of kexec system call. This system call is
file based and takes file descriptors as system call argument
for kernel and initramfs as opposed to list of segments as
accepted by previous system call.
If you don't know what to do here, say Y.
config ARCH_HAS_KEXEC_PURGATORY
def_bool KEXEC_FILE
depends on CRYPTO=y
depends on CRYPTO_SHA256=y
config CRASH_DUMP
bool "Build kdump crash kernel"
help
Generate crash dump after being started by kexec. This should
be normally only set in special crash dump kernels which are
loaded in the main kernel with kexec-tools into a specially
reserved region and then later executed after a crash by
kdump/kexec.
For more details see Documentation/admin-guide/kdump/kdump.rst
config COMPAT
bool "Kernel support for 32-bit U-mode"
default 64BIT
depends on 64BIT && MMU
help
This option enables support for a 32-bit U-mode running under a 64-bit
kernel at S-mode. riscv32-specific components such as system calls,
the user helper functions (vdso), signal rt_frame functions and the
ptrace interface are handled appropriately by the kernel.
If you want to execute 32-bit userspace applications, say Y.
config RELOCATABLE
bool "Build a relocatable kernel"
depends on MMU && 64BIT && !XIP_KERNEL
help
This builds a kernel as a Position Independent Executable (PIE),
which retains all relocation metadata required to relocate the
kernel binary at runtime to a different virtual address than the
address it was linked at.
Since RISCV uses the RELA relocation format, this requires a
relocation pass at runtime even if the kernel is loaded at the
same address it was linked at.
If unsure, say N.
endmenu # "Kernel features"
menu "Boot options"
config CMDLINE
string "Built-in kernel command line"
help
For most platforms, the arguments for the kernel's command line
are provided at run-time, during boot. However, there are cases
where either no arguments are being provided or the provided
arguments are insufficient or even invalid.
When that occurs, it is possible to define a built-in command
line here and choose how the kernel should use it later on.
choice
prompt "Built-in command line usage" if CMDLINE != ""
default CMDLINE_FALLBACK
help
Choose how the kernel will handle the provided built-in command
line.
config CMDLINE_FALLBACK
bool "Use bootloader kernel arguments if available"
help
Use the built-in command line as fallback in case we get nothing
during boot. This is the default behaviour.
config CMDLINE_EXTEND
bool "Extend bootloader kernel arguments"
help
The command-line arguments provided during boot will be
appended to the built-in command line. This is useful in
cases where the provided arguments are insufficient and
you don't want to or cannot modify them.
config CMDLINE_FORCE
bool "Always use the default kernel command string"
help
Always use the built-in command line, even if we get one during
boot. This is useful in case you need to override the provided
command line on systems where you don't have or want control
over it.
endchoice
config EFI_STUB
bool
config EFI
bool "UEFI runtime support"
depends on OF && !XIP_KERNEL
depends on MMU
default y
select EFI_GENERIC_STUB
select EFI_PARAMS_FROM_FDT
select EFI_RUNTIME_WRAPPERS
select EFI_STUB
select LIBFDT
select RISCV_ISA_C
select UCS2_STRING
help
This option provides support for runtime services provided
by UEFI firmware (such as non-volatile variables, realtime
clock, and platform reset). A UEFI stub is also provided to
allow the kernel to be booted as an EFI application. This
is only useful on systems that have UEFI firmware.
config CC_HAVE_STACKPROTECTOR_TLS
def_bool $(cc-option,-mstack-protector-guard=tls -mstack-protector-guard-reg=tp -mstack-protector-guard-offset=0)
config STACKPROTECTOR_PER_TASK
def_bool y
depends on !RANDSTRUCT
depends on STACKPROTECTOR && CC_HAVE_STACKPROTECTOR_TLS
config PHYS_RAM_BASE_FIXED
bool "Explicitly specified physical RAM address"
depends on NONPORTABLE
default n
config PHYS_RAM_BASE
hex "Platform Physical RAM address"
depends on PHYS_RAM_BASE_FIXED
default "0x80000000"
help
This is the physical address of RAM in the system. It has to be
explicitly specified to run early relocations of read-write data
from flash to RAM.
config XIP_KERNEL
bool "Kernel Execute-In-Place from ROM"
depends on MMU && SPARSEMEM && NONPORTABLE
# This prevents XIP from being enabled by all{yes,mod}config, which
# fail to build since XIP doesn't support large kernels.
depends on !COMPILE_TEST
select PHYS_RAM_BASE_FIXED
help
Execute-In-Place allows the kernel to run from non-volatile storage
directly addressable by the CPU, such as NOR flash. This saves RAM
space since the text section of the kernel is not loaded from flash
to RAM. Read-write sections, such as the data section and stack,
are still copied to RAM. The XIP kernel is not compressed since
it has to run directly from flash, so it will take more space to
store it. The flash address used to link the kernel object files,
and for storing it, is configuration dependent. Therefore, if you
say Y here, you must know the proper physical address where to
store the kernel image depending on your own flash memory usage.
Also note that the make target becomes "make xipImage" rather than
"make zImage" or "make Image". The final kernel binary to put in
ROM memory will be arch/riscv/boot/xipImage.
SPARSEMEM is required because the kernel text and rodata that are
flash resident are not backed by memmap, then any attempt to get
a struct page on those regions will trigger a fault.
If unsure, say N.
config XIP_PHYS_ADDR
hex "XIP Kernel Physical Location"
depends on XIP_KERNEL
default "0x21000000"
help
This is the physical address in your flash memory the kernel will
be linked for and stored to. This address is dependent on your
own flash usage.
endmenu # "Boot options"
config BUILTIN_DTB
bool
depends on OF && NONPORTABLE
default y if XIP_KERNEL
config PORTABLE
bool
default !NONPORTABLE
select EFI
select MMU
select OF
menu "Power management options"
source "kernel/power/Kconfig"
# Hibernation is only possible on systems where the SBI implementation has
# marked its reserved memory as not accessible from, or does not run
# from the same memory as, Linux
config ARCH_HIBERNATION_POSSIBLE
def_bool NONPORTABLE
config ARCH_HIBERNATION_HEADER
def_bool HIBERNATION
endmenu # "Power management options"
menu "CPU Power Management"
source "drivers/cpuidle/Kconfig"
source "drivers/cpufreq/Kconfig"
endmenu # "CPU Power Management"
source "arch/riscv/kvm/Kconfig"
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