Dumping the dtb from new versions of QEMU warns that sv57 is an
undocumented mmu-type. The kernel has supported sv57 for about a year,
so bring it into the fold.
Signed-off-by: Conor Dooley <conor.dooley@microchip.com>
Acked-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20230424-rival-habitual-478567c516f0@spud
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
probe_vendor_features() is now called from smp_callin(), which is not
__init code and runs during cpu hotplug events. Remove the
__init_or_module decoration from it and the functions it calls to avoid
walking into outer space.
Fixes: 62a31d6e38 ("RISC-V: hwprobe: Support probing of misaligned access performance")
Signed-off-by: Evan Green <evan@rivosinc.com>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20230420194934.1871356-1-evan@rivosinc.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
Alexandre Ghiti <alexghiti@rivosinc.com> says:
After multiple attempts, this patchset is now based on the fact that the
64b kernel mapping was moved outside the linear mapping.
The first patch allows to build relocatable kernels but is not selected
by default. That patch is a requirement for KASLR.
The second and third patches take advantage of an already existing powerpc
script that checks relocations at compile-time, and uses it for riscv.
* b4-shazam-merge:
riscv: Use --emit-relocs in order to move .rela.dyn in init
riscv: Check relocations at compile time
powerpc: Move script to check relocations at compile time in scripts/
riscv: Introduce CONFIG_RELOCATABLE
riscv: Move .rela.dyn outside of init to avoid empty relocations
riscv: Prepare EFI header for relocatable kernels
Link: https://lore.kernel.org/r/20230329045329.64565-1-alexghiti@rivosinc.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
To circumvent an issue where placing the relocations inside the init
sections produces empty relocations, use --emit-relocs. But to avoid
carrying those relocations in vmlinux, use an intermediate
vmlinux.relocs file which is a copy of vmlinux *before* stripping its
relocations.
Suggested-by: Björn Töpel <bjorn@kernel.org>
Suggested-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Alexandre Ghiti <alexghiti@rivosinc.com>
Link: https://lore.kernel.org/r/20230329045329.64565-7-alexghiti@rivosinc.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
Relocating kernel at runtime is done very early in the boot process, so
it is not convenient to check for relocations there and react in case a
relocation was not expected.
There exists a script in scripts/ that extracts the relocations from
vmlinux that is then used at postlink to check the relocations.
Signed-off-by: Alexandre Ghiti <alex@ghiti.fr>
Reviewed-by: Anup Patel <anup@brainfault.org>
Link: https://lore.kernel.org/r/20230329045329.64565-6-alexghiti@rivosinc.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
Relocating kernel at runtime is done very early in the boot process, so
it is not convenient to check for relocations there and react in case a
relocation was not expected.
Powerpc architecture has a script that allows to check at compile time
for such unexpected relocations: extract the common logic to scripts/
so that other architectures can take advantage of it.
Signed-off-by: Alexandre Ghiti <alex@ghiti.fr>
Reviewed-by: Anup Patel <anup@brainfault.org>
Acked-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc)
Link: https://lore.kernel.org/r/20230329045329.64565-5-alexghiti@rivosinc.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
This config allows to compile 64b kernel as PIE and to relocate it at
any virtual address at runtime: this paves the way to KASLR.
Runtime relocation is possible since relocation metadata are embedded into
the kernel.
Note that relocating at runtime introduces an overhead even if the
kernel is loaded at the same address it was linked at and that the compiler
options are those used in arm64 which uses the same RELA relocation
format.
Signed-off-by: Alexandre Ghiti <alexghiti@rivosinc.com>
Link: https://lore.kernel.org/r/20230329045329.64565-4-alexghiti@rivosinc.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
Alexandre Ghiti <alexghiti@rivosinc.com> says:
As described in patch 2, our current kasan implementation is intricate,
so I tried to simplify the implementation and mimic what arm64/x86 are
doing.
In addition it fixes UEFI bootflow with a kasan kernel and kasan inline
instrumentation: all kasan configurations were tested on a large ubuntu
kernel with success with KASAN_KUNIT_TEST and KASAN_MODULE_TEST.
inline ubuntu config + uefi:
sv39: OK
sv48: OK
sv57: OK
outline ubuntu config + uefi:
sv39: OK
sv48: OK
sv57: OK
Actually 1 test always fails with KASAN_KUNIT_TEST that I have to check:
KASAN failure expected in "set_bit(nr, addr)", but none occurrred
Note that Palmer recently proposed to remove COMMAND_LINE_SIZE from the
userspace abi
https://lore.kernel.org/lkml/20221211061358.28035-1-palmer@rivosinc.com/T/
so that we can finally increase the command line to fit all kasan kernel
parameters.
All of this should hopefully fix the syzkaller riscv build that has been
failing for a few months now, any test is appreciated and if I can help
in any way, please ask.
* b4-shazam-merge:
riscv: Unconditionnally select KASAN_VMALLOC if KASAN
riscv: Fix ptdump when KASAN is enabled
riscv: Fix EFI stub usage of KASAN instrumented strcmp function
riscv: Move DTB_EARLY_BASE_VA to the kernel address space
riscv: Rework kasan population functions
riscv: Split early and final KASAN population functions
Link: https://lore.kernel.org/r/20230203075232.274282-1-alexghiti@rivosinc.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
If KASAN is enabled, VMAP_STACK depends on KASAN_VMALLOC so enable
KASAN_VMALLOC with KASAN so that we can enable VMAP_STACK by default.
Signed-off-by: Alexandre Ghiti <alexghiti@rivosinc.com>
Reviewed-by: Björn Töpel <bjorn@rivosinc.com>
Link: https://lore.kernel.org/r/20230203075232.274282-7-alexghiti@rivosinc.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
The KASAN shadow region was moved next to the kernel mapping but the
ptdump code was not updated and it appears to break the dump of the kernel
page table, so fix this by moving the KASAN shadow region in ptdump.
Fixes: f7ae02333d ("riscv: Move KASAN mapping next to the kernel mapping")
Signed-off-by: Alexandre Ghiti <alexghiti@rivosinc.com>
Tested-by: Björn Töpel <bjorn@rivosinc.com>
Reviewed-by: Björn Töpel <bjorn@rivosinc.com>
Link: https://lore.kernel.org/r/20230203075232.274282-6-alexghiti@rivosinc.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
The EFI stub must not use any KASAN instrumented code as the kernel
proper did not initialize the thread pointer and the mapping for the
KASAN shadow region.
Avoid using the generic strcmp function, instead use the one in
drivers/firmware/efi/libstub/string.c.
Signed-off-by: Alexandre Ghiti <alexghiti@rivosinc.com>
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Reviewed-by: Atish Patra <atishp@rivosinc.com>
Link: https://lore.kernel.org/r/20230203075232.274282-5-alexghiti@rivosinc.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
The early virtual address should lie in the kernel address space for
inline kasan instrumentation to succeed, otherwise kasan tries to
dereference an address that does not exist in the address space (since
kasan only maps *kernel* address space, not the userspace).
Simply use the very first address of the kernel address space for the
early fdt mapping.
It allowed an Ubuntu kernel to boot successfully with inline
instrumentation.
Signed-off-by: Alexandre Ghiti <alexghiti@rivosinc.com>
Reviewed-by: Björn Töpel <bjorn@rivosinc.com>
Link: https://lore.kernel.org/r/20230203075232.274282-4-alexghiti@rivosinc.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
Our previous kasan population implementation used to have the final kasan
shadow region mapped with kasan_early_shadow_page, because we did not clean
the early mapping and then we had to populate the kasan region "in-place"
which made the code cumbersome.
So now we clear the early mapping, establish a temporary mapping while we
populate the kasan shadow region with just the kernel regions that will
be used.
This new version uses the "generic" way of going through a page table
that may be folded at runtime (avoid the XXX_next macros).
It was tested with outline instrumentation on an Ubuntu kernel
configuration successfully.
Signed-off-by: Alexandre Ghiti <alexghiti@rivosinc.com>
Reviewed-by: Björn Töpel <bjorn@rivosinc.com>
Link: https://lore.kernel.org/r/20230203075232.274282-3-alexghiti@rivosinc.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
This is a preliminary work that allows to make the code more
understandable.
Signed-off-by: Alexandre Ghiti <alexghiti@rivosinc.com>
Reviewed-by: Björn Töpel <bjorn@rivosinc.com>
Link: https://lore.kernel.org/r/20230203075232.274282-2-alexghiti@rivosinc.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
Alexandre Ghiti <alexghiti@rivosinc.com> says:
This patchset intends to improve tlb utilization by using hugepages for
the linear mapping.
As reported by Anup in v6, when STRICT_KERNEL_RWX is enabled, we must
take care of isolating the kernel text and rodata so that they are not
mapped with a PUD mapping which would then assign wrong permissions to
the whole region: it is achieved the same way as arm64 by using the
memblock nomap API which isolates those regions and re-merge them afterwards
thus avoiding any issue with the system resources tree creation.
arch/riscv/include/asm/page.h | 19 ++++++-
arch/riscv/mm/init.c | 102 ++++++++++++++++++++++++++--------
arch/riscv/mm/physaddr.c | 16 ++++++
drivers/of/fdt.c | 11 ++--
4 files changed, 118 insertions(+), 30 deletions(-)
* b4-shazam-merge:
riscv: Use PUD/P4D/PGD pages for the linear mapping
riscv: Move the linear mapping creation in its own function
riscv: Get rid of riscv_pfn_base variable
Link: https://lore.kernel.org/r/20230324155421.271544-1-alexghiti@rivosinc.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
During the early page table creation, we used to set the mapping for
PAGE_OFFSET to the kernel load address: but the kernel load address is
always offseted by PMD_SIZE which makes it impossible to use PUD/P4D/PGD
pages as this physical address is not aligned on PUD/P4D/PGD size (whereas
PAGE_OFFSET is).
But actually we don't have to establish this mapping (ie set va_pa_offset)
that early in the boot process because:
- first, setup_vm installs a temporary kernel mapping and among other
things, discovers the system memory,
- then, setup_vm_final creates the final kernel mapping and takes
advantage of the discovered system memory to create the linear
mapping.
During the first phase, we don't know the start of the system memory and
then until the second phase is finished, we can't use the linear mapping at
all and phys_to_virt/virt_to_phys translations must not be used because it
would result in a different translation from the 'real' one once the final
mapping is installed.
So here we simply delay the initialization of va_pa_offset to after the
system memory discovery. But to make sure noone uses the linear mapping
before, we add some guard in the DEBUG_VIRTUAL config.
Finally we can use PUD/P4D/PGD hugepages when possible, which will result
in a better TLB utilization.
Note that:
- this does not apply to rv32 as the kernel mapping lies in the linear
mapping.
- we rely on the firmware to protect itself using PMP.
Signed-off-by: Alexandre Ghiti <alexghiti@rivosinc.com>
Acked-by: Rob Herring <robh@kernel.org> # DT bits
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
Tested-by: Anup Patel <anup@brainfault.org>
Link: https://lore.kernel.org/r/20230324155421.271544-4-alexghiti@rivosinc.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
No change intended, it just splits the linear mapping creation from
setup_vm_final: this prepares for upcoming additions to the linear
mapping creation.
Signed-off-by: Alexandre Ghiti <alexghiti@rivosinc.com>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
Tested-by: Anup Patel <anup@brainfault.org>
Link: https://lore.kernel.org/r/20230324155421.271544-3-alexghiti@rivosinc.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
Use directly phys_ram_base instead, riscv_pfn_base is just the pfn of
the address contained in phys_ram_base.
Even if there is no functional change intended in this patch, actually
setting phys_ram_base that early changes the behaviour of
kernel_mapping_pa_to_va during the early boot: phys_ram_base used to be
zero before this patch and now it is set to the physical start address of
the kernel. But it does not break the conversion of a kernel physical
address into a virtual address since kernel_mapping_pa_to_va should only
be used on kernel physical addresses, i.e. addresses greater than the
physical start address of the kernel.
Signed-off-by: Alexandre Ghiti <alexghiti@rivosinc.com>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
Tested-by: Anup Patel <anup@brainfault.org>
Link: https://lore.kernel.org/r/20230324155421.271544-2-alexghiti@rivosinc.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
Other extensions only capitalise the first letter in the text visible
in Kconfig menus, and provide a short comment about the extension's
meaning. Do the same for Svnapot & Svpbmt.
The precedent for capitalisation in the Kconfig text was set by Zicbom
& sorta followed for Zicboz. The RVI styling used for multi-letter
extensions only capitalises the first letter, so do the same here.
If nothing else, my OCD likes it when the extensions follow a consistent
pattern.
While editing one of the lines, reformat the "spelling" of 64-bit.
Signed-off-by: Conor Dooley <conor.dooley@microchip.com>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Link: https://lore.kernel.org/r/20230405-pucker-cogwheel-3a999a94a2f2@wendy
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
RISC-V now builds the sched domain based on the simple possible map.
Enable SCHED_MC to make the building based on cpu_coregroup_mask()
which also takes care of the NUMA and cores with LLC.
Signed-off-by: Song Shuai <suagrfillet@gmail.com>
Acked-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20230310110336.970985-1-suagrfillet@gmail.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
RISC-V now manages CPU topology using arch_topology which provides
CPU capacity and frequency related interfaces to access the cpu/freq
invariant in possible heterogeneous or DVFS-enabled platforms.
Here adds topology.h file to export the arch_topology interfaces for
replacing the scheduler's constant-based cpu/freq invariant accounting.
Signed-off-by: Song Shuai <suagrfillet@gmail.com>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Reviewed-by: Ley Foon Tan <lftan@kernel.org>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20230323123924.3032174-1-suagrfillet@gmail.com
[Palmer: Fix the whitespace issues.]
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
Evan Green <evan@rivosinc.com> says:
There's been a bunch of off-list discussions about this, including at
Plumbers. The original plan was to do something involving providing an
ISA string to userspace, but ISA strings just aren't sufficient for a
stable ABI any more: in order to parse an ISA string users need the
version of the specifications that the string is written to, the version
of each extension (sometimes at a finer granularity than the RISC-V
releases/versions encode), and the expected use case for the ISA string
(ie, is it a U-mode or M-mode string). That's a lot of complexity to
try and keep ABI compatible and it's probably going to continue to grow,
as even if there's no more complexity in the specifications we'll have
to deal with the various ISA string parsing oddities that end up all
over userspace.
Instead this patch set takes a very different approach and provides a set
of key/value pairs that encode various bits about the system. The big
advantage here is that we can clearly define what these mean so we can
ensure ABI stability, but it also allows us to encode information that's
unlikely to ever appear in an ISA string (see the misaligned access
performance, for example). The resulting interface looks a lot like
what arm64 and x86 do, and will hopefully fit well into something like
ACPI in the future.
The actual user interface is a syscall, with a vDSO function in front of
it. The vDSO function can answer some queries without a syscall at all,
and falls back to the syscall for cases it doesn't have answers to.
Currently we prepopulate it with an array of answers for all keys and
a CPU set of "all CPUs". This can be adjusted as necessary to provide
fast answers to the most common queries.
An example series in glibc exposing this syscall and using it in an
ifunc selector for memcpy can be found at [1].
I was asked about the performance delta between this and something like
sysfs. I created a small test program and ran it on a Nezha D1
Allwinner board. Doing each operation 100000 times and dividing, these
operations take the following amount of time:
- open()+read()+close() of /sys/kernel/cpu_byteorder: 3.8us
- access("/sys/kernel/cpu_byteorder", R_OK): 1.3us
- riscv_hwprobe() vDSO and syscall: .0094us
- riscv_hwprobe() vDSO with no syscall: 0.0091us
These numbers get farther apart if we query multiple keys, as sysfs will
scale linearly with the number of keys, where the dedicated syscall
stays the same. To frame these numbers, I also did a tight
fork/exec/wait loop, which I measured as 4.8ms. So doing 4
open/read/close operations is a delta of about 0.3%, versus a single vDSO
call is a delta of essentially zero.
[1] https://patchwork.ozlabs.org/project/glibc/list/?series=343050
* b4-shazam-merge:
RISC-V: Add hwprobe vDSO function and data
selftests: Test the new RISC-V hwprobe interface
RISC-V: hwprobe: Support probing of misaligned access performance
RISC-V: hwprobe: Add support for RISCV_HWPROBE_BASE_BEHAVIOR_IMA
RISC-V: Add a syscall for HW probing
RISC-V: Move struct riscv_cpuinfo to new header
Link: https://lore.kernel.org/r/20230407231103.2622178-1-evan@rivosinc.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
Add a vDSO function __vdso_riscv_hwprobe, which can sit in front of the
riscv_hwprobe syscall and answer common queries. We stash a copy of
static answers for the "all CPUs" case in the vDSO data page. This data
is private to the vDSO, so we can decide later to change what's stored
there or under what conditions we defer to the syscall. Currently all
data can be discovered at boot, so the vDSO function answers all queries
when the cpumask is set to the "all CPUs" hint.
There's also a boolean in the data that lets the vDSO function know that
all CPUs are the same. In that case, the vDSO will also answer queries
for arbitrary CPU masks in addition to the "all CPUs" hint.
Signed-off-by: Evan Green <evan@rivosinc.com>
Link: https://lore.kernel.org/r/20230407231103.2622178-7-evan@rivosinc.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
This adds a test for the recently added RISC-V interface for probing
hardware capabilities. It happens to be the first selftest we have for
RISC-V, so I've added some infrastructure for those as well.
Co-developed-by: Palmer Dabbelt <palmer@rivosinc.com>
Signed-off-by: Evan Green <evan@rivosinc.com>
Link: https://lore.kernel.org/r/20230407231103.2622178-6-evan@rivosinc.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
This allows userspace to select various routines to use based on the
performance of misaligned access on the target hardware.
Rather than adding DT bindings, this change taps into the alternatives
mechanism used to probe CPU errata. Add a new function pointer alongside
the vendor-specific errata_patch_func() that probes for desirable errata
(otherwise known as "features"). Unlike the errata_patch_func(), this
function is called on each CPU as it comes up, so it can save
feature information per-CPU.
The T-head C906 has fast unaligned access, both as defined by GCC [1],
and in performing a basic benchmark, which determined that byte copies
are >50% slower than a misaligned word copy of the same data size (source
for this test at [2]):
bytecopy size f000 count 50000 offset 0 took 31664899 us
wordcopy size f000 count 50000 offset 0 took 5180919 us
wordcopy size f000 count 50000 offset 1 took 13416949 us
[1] https://github.com/gcc-mirror/gcc/blob/master/gcc/config/riscv/riscv.cc#L353
[2] https://pastebin.com/EPXvDHSW
Co-developed-by: Palmer Dabbelt <palmer@rivosinc.com>
Signed-off-by: Evan Green <evan@rivosinc.com>
Reviewed-by: Heiko Stuebner <heiko.stuebner@vrull.eu>
Tested-by: Heiko Stuebner <heiko.stuebner@vrull.eu>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Reviewed-by: Paul Walmsley <paul.walmsley@sifive.com>
Link: https://lore.kernel.org/r/20230407231103.2622178-5-evan@rivosinc.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
We have an implicit set of base behaviors that userspace depends on,
which are mostly defined in various ISA specifications.
Co-developed-by: Palmer Dabbelt <palmer@rivosinc.com>
Signed-off-by: Evan Green <evan@rivosinc.com>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Reviewed-by: Heiko Stuebner <heiko.stuebner@vrull.eu>
Tested-by: Heiko Stuebner <heiko.stuebner@vrull.eu>
Reviewed-by: Paul Walmsley <paul.walmsley@sifive.com>
Link: https://lore.kernel.org/r/20230407231103.2622178-4-evan@rivosinc.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
We don't have enough space for these all in ELF_HWCAP{,2} and there's no
system call that quite does this, so let's just provide an arch-specific
one to probe for hardware capabilities. This currently just provides
m{arch,imp,vendor}id, but with the key-value pairs we can pass more in
the future.
Co-developed-by: Palmer Dabbelt <palmer@rivosinc.com>
Signed-off-by: Evan Green <evan@rivosinc.com>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Reviewed-by: Heiko Stuebner <heiko.stuebner@vrull.eu>
Tested-by: Heiko Stuebner <heiko.stuebner@vrull.eu>
Reviewed-by: Paul Walmsley <paul.walmsley@sifive.com>
Link: https://lore.kernel.org/r/20230407231103.2622178-3-evan@rivosinc.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
In preparation for tracking and exposing microarchitectural details to
userspace (like whether or not unaligned accesses are fast), move the
riscv_cpuinfo struct out to its own new cpufeatures.h header. It will
need to be used by more than just cpu.c.
Signed-off-by: Evan Green <evan@rivosinc.com>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Reviewed-by: Heiko Stuebner <heiko.stuebner@vrull.eu>
Tested-by: Heiko Stuebner <heiko.stuebner@vrull.eu>
Reviewed-by: Paul Walmsley <paul.walmsley@sifive.com>
Link: https://lore.kernel.org/r/20230407231103.2622178-2-evan@rivosinc.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
This reverts commit baf7cbd94b.
There are some duplicate cache attributes populations executed
in both ci_leaf_init() and later cache_setup_properties().
Revert the commit baf7cbd94b ("riscv: Set more data to cacheinfo")
to setup only the level and type attributes at this early place.
Signed-off-by: Song Shuai <suagrfillet@gmail.com>
Acked-by: Sudeep Holla <sudeep.holla@arm.com>
Acked-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20230308064734.512457-1-suagrfillet@gmail.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
The RISC-V calling convention passes the first argument, and the
return value in the a0 register. For this reason, the a0 register
needs some extra care; When handling syscalls, the a0 register is
saved into regs->orig_a0, so a0 can be properly restored for,
e.g. interrupted syscalls.
This functionality was broken with the introduction of the generic
entry patches. Here, a0 was saved into orig_a0 after calling
syscall_enter_from_user_mode(), which can change regs->a0 for some
paths, incorrectly restoring a0.
This is resolved, by saving a0 prior doing the
syscall_enter_from_user_mode() call.
Fixes: f0bddf5058 ("riscv: entry: Convert to generic entry")
Reviewed-by: Heiko Stuebner <heiko.stuebner@vrull.eu>
Tested-by: Heiko Stuebner <heiko.stuebner@vrull.eu>
Signed-off-by: Björn Töpel <bjorn@rivosinc.com>
Reported-by: Conor Dooley <conor.dooley@microchip.com>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Tested-by: Conor Dooley <conor.dooley@microchip.com>
Tested-by: Geert Uytterhoeven <geert+renesas@glider.be>
Tested-by: Andy Chiu <andy.chiu@sifive.com>
Link: https://lore.kernel.org/r/20230403065207.1070974-1-bjorn@kernel.org
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
for-next contains two additional extensions that select
RISCV_ALTERNATIVE. RISCV_ALTERNATIVE no longer needs to be selected by
individual config options as it is now selected for !XIP_KERNEL builds
by the top level RISCV option.
These extensions rely on the alternative framework, so convert the
"select"s to "depends on"s instead.
Signed-off-by: Conor Dooley <conor.dooley@microchip.com>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Link: https://lore.kernel.org/r/20230324121240.3594777-1-conor.dooley@microchip.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
Conor Dooley <conor.dooley@microchip.com> says:
Here's my attempt at fixing both the use of an FPU on XIP kernels and
the issue that Jason ran into where CONFIG_FPU, which needs the
alternatives frame work for has_fpu() checks, could be enabled without
the alternatives actually being present.
For the former, a "slow" fallback that does not use alternatives is
added to riscv_has_extension_[un]likely() that can be used with XIP.
Obviously, we want to make use of Jisheng's alternatives based approach
where possible, so any users of riscv_has_extension_[un]likely() will
want to make sure that they select RISCV_ALTERNATIVE.
If they don't however, they'll hit the fallback path which (should,
sparing a silly mistake from me!) behave in the same way, thus
succeeding silently. Sounds like a
To prevent "depends on !XIP_KERNEL; select RISCV_ALTERNATIVE" spreading
like the plague through the various places that want to check for the
presence of extensions, and sidestep the potential silent "success"
mentioned above, all users RISCV_ALTERNATIVE are converted from selects
to dependencies, with the option being selected for all !XIP_KERNEL
builds.
I know that the VDSO was a key place that Jisheng wanted to use the new
helper rather than static branches, and I think the fallback path
should not cause issues there.
See the thread at [1] for the prior discussion.
1 - https://lore.kernel.org/linux-riscv/20230128172856.3814-1-jszhang@kernel.org/T/#m21390d570997145d31dd8bb95002fd61f99c6573
[Palmer: these were also merged into fixes, but there's a cleanup that
depends on the merge so I'm taking it into for-next as well.]
* b4-shazam-merge:
RISC-V: always select RISCV_ALTERNATIVE for non-xip kernels
RISC-V: add non-alternative fallback for riscv_has_extension_[un]likely()
Link: https://lore.kernel.org/r/20230324100538.3514663-1-conor.dooley@microchip.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
* commit '1ee7fc3f4d0a93831a20d5566f203d5ad6d44de8':
RISC-V: always select RISCV_ALTERNATIVE for non-xip kernels
RISC-V: add non-alternative fallback for riscv_has_extension_[un]likely()
When moving switch_to's has_fpu() over to using
riscv_has_extension_likely() rather than static branches, the FPU code
gained a dependency on the alternatives framework.
That dependency has now been removed, as riscv_has_extension_ikely() now
contains a fallback path, using __riscv_isa_extension_available(), but
if CONFIG_RISCV_ALTERNATIVE isn't selected when CONFIG_FPU is, has_fpu()
checks will not benefit from the "fast path" that the alternatives
framework provides.
We want to ensure that alternatives are available whenever
riscv_has_extension_[un]likely() is used, rather than silently falling
back to the slow path, but rather than rely on selecting
RISCV_ALTERNATIVE in the myriad of locations that may use
riscv_has_extension_[un]likely(), select it (almost) always instead by
adding it to the main RISCV config entry.
xip kernels cannot make use of the alternatives framework, so it is not
enabled for those configurations, although this is the status quo.
All current sites that select RISCV_ALTERNATIVE are converted to
dependencies on the option instead. The explicit dependencies on
!XIP_KERNEL can be dropped, as RISCV_ALTERNATIVE is not user selectable.
Fixes: 702e64550b ("riscv: fpu: switch has_fpu() to riscv_has_extension_likely()")
Link: https://lore.kernel.org/all/ZBruFRwt3rUVngPu@zx2c4.com/
Reported-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Conor Dooley <conor.dooley@microchip.com>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Reviewed-by: Jason A. Donenfeld <Jason@zx2c4.com>
Link: https://lore.kernel.org/r/20230324100538.3514663-3-conor.dooley@microchip.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
The has_fpu() check, which in turn calls riscv_has_extension_likely(),
relies on alternatives to figure out whether the system has an FPU.
As a result, it will malfunction on XIP kernels, as they do not support
the alternatives mechanism.
When alternatives support is not present, fall back to using
__riscv_isa_extension_available() in riscv_has_extension_[un]likely()
instead stead, which handily takes the same argument, so that kernels
that do not support alternatives can accurately report the presence of
FPU support.
Fixes: 702e64550b ("riscv: fpu: switch has_fpu() to riscv_has_extension_likely()")
Link: https://lore.kernel.org/all/ad445951-3d13-4644-94d9-e0989cda39c3@spud/
Signed-off-by: Conor Dooley <conor.dooley@microchip.com>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Reviewed-by: Jason A. Donenfeld <Jason@zx2c4.com>
Link: https://lore.kernel.org/r/20230324100538.3514663-2-conor.dooley@microchip.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
Jesse Taube <mr.bossman075@gmail.com> says:
This patch-set aims to add NOMMU support to RV32.
Many people want to build simple emulators or HDL
models of RISC-V this patch makes it possible to
run linux on them.
Yimin Gu is the original author of this set.
Submitted here:
https://lists.buildroot.org/pipermail/buildroot/2022-November/656134.html
Though Jesse T rewrote the Dconf.
* b4-shazam-merge:
riscv: configs: Add nommu PHONY defconfig for RV32
riscv: Kconfig: Allow RV32 to build with no MMU
Link: https://lore.kernel.org/r/20230301002657.352637-1-Mr.Bossman075@gmail.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
32bit risc-v can be configured to run without MMU. Introduce
rv32_nommu_virt_defconfig .PHONY target, that is based on
nommu_virt_defconfig. This is similar to how rv32_defconfig
is based on "defconfig".
Suggested-by: Conor Dooley <conor@kernel.org>
Signed-off-by: Jesse Taube <Mr.Bossman075@gmail.com>
Cc: Yimin Gu <ustcymgu@gmail.com>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20230301002657.352637-4-Mr.Bossman075@gmail.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
Some RISC-V 32bit cores do not have an MMU, and the kernel should be
able to build for them. This patch enables the RV32 to be built with
no MMU support.
Signed-off-by: Yimin Gu <ustcymgu@gmail.com>
CC: Jesse Taube <Mr.Bossman075@gmail.com>
Tested-by: Waldemar Brodkorb <wbx@openadk.org>
Signed-off-by: Jesse Taube <Mr.Bossman075@gmail.com>
Reviewed-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20230301002657.352637-3-Mr.Bossman075@gmail.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
guoren@kernel.org <guoren@kernel.org> says:
From: Guo Ren <guoren@linux.alibaba.com>
The patches convert riscv to use the generic entry infrastructure from
kernel/entry/*. Some optimization for entry.S with new .macro and merge
ret_from_kernel_thread into ret_from_fork.
* b4-shazam-merge:
riscv: entry: Consolidate general regs saving/restoring
riscv: entry: Consolidate ret_from_kernel_thread into ret_from_fork
riscv: entry: Remove extra level wrappers of trace_hardirqs_{on,off}
riscv: entry: Convert to generic entry
riscv: entry: Add noinstr to prevent instrumentation inserted
riscv: ptrace: Remove duplicate operation
Link: https://lore.kernel.org/r/20230222033021.983168-1-guoren@kernel.org
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
The ret_from_kernel_thread() behaves similarly with ret_from_fork(),
the only difference is whether call the fn(arg) or not, this can be
achieved by testing fn is NULL or not, I.E s0 is 0 or not. Many
architectures have done the same thing, it makes entry.S more clean.
Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
Reviewed-by: Björn Töpel <bjorn@rivosinc.com>
Reviewed-by: Guo Ren <guoren@kernel.org>
Tested-by: Guo Ren <guoren@kernel.org>
Signed-off-by: Guo Ren <guoren@kernel.org>
Link: https://lore.kernel.org/r/20230222033021.983168-7-guoren@kernel.org
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
Since riscv is converted to generic entry, there's no need for the
extra wrappers of trace_hardirqs_{on,off}.
Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
Reviewed-by: Guo Ren <guoren@kernel.org>
Reviewed-by: Björn Töpel <bjorn@rivosinc.com>
Tested-by: Guo Ren <guoren@kernel.org>
Signed-off-by: Guo Ren <guoren@kernel.org>
Link: https://lore.kernel.org/r/20230222033021.983168-6-guoren@kernel.org
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
This patch converts riscv to use the generic entry infrastructure from
kernel/entry/*. The generic entry makes maintainers' work easier and
codes more elegant. Here are the changes:
- More clear entry.S with handle_exception and ret_from_exception
- Get rid of complex custom signal implementation
- Move syscall procedure from assembly to C, which is much more
readable.
- Connect ret_from_fork & ret_from_kernel_thread to generic entry.
- Wrap with irqentry_enter/exit and syscall_enter/exit_from_user_mode
- Use the standard preemption code instead of custom
Suggested-by: Huacai Chen <chenhuacai@kernel.org>
Reviewed-by: Björn Töpel <bjorn@rivosinc.com>
Tested-by: Yipeng Zou <zouyipeng@huawei.com>
Tested-by: Jisheng Zhang <jszhang@kernel.org>
Signed-off-by: Guo Ren <guoren@linux.alibaba.com>
Signed-off-by: Guo Ren <guoren@kernel.org>
Cc: Ben Hutchings <ben@decadent.org.uk>
Link: https://lore.kernel.org/r/20230222033021.983168-5-guoren@kernel.org
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
Without noinstr the compiler is free to insert instrumentation (think
all the k*SAN, KCov, GCov, ftrace etc..) which can call code we're not
yet ready to run this early in the entry path, for instance it could
rely on RCU which isn't on yet, or expect lockdep state. (by peterz)
Link: https://lore.kernel.org/linux-riscv/YxcQ6NoPf3AH0EXe@hirez.programming.kicks-ass.net/
Reviewed-by: Björn Töpel <bjorn@rivosinc.com>
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Tested-by: Jisheng Zhang <jszhang@kernel.org>
Signed-off-by: Guo Ren <guoren@linux.alibaba.com>
Signed-off-by: Guo Ren <guoren@kernel.org>
Link: https://lore.kernel.org/r/20230222033021.983168-4-guoren@kernel.org
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
The TIF_SYSCALL_TRACE is controlled by a common code, see
kernel/ptrace.c and include/linux/thread_info.h.
clear_task_syscall_work(child, SYSCALL_TRACE);
Signed-off-by: Guo Ren <guoren@linux.alibaba.com>
Signed-off-by: Guo Ren <guoren@kernel.org>
Reviewed-by: Oleg Nesterov <oleg@redhat.com>
Reviewed-by: Björn Töpel <bjorn@rivosinc.com>
Link: https://lore.kernel.org/r/20230222033021.983168-3-guoren@kernel.org
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
Andrew Jones <ajones@ventanamicro.com> says:
When the Zicboz extension is available we can more rapidly zero naturally
aligned Zicboz block sized chunks of memory. As pages are always page
aligned and are larger than any Zicboz block size will be, then
clear_page() appears to be a good candidate for the extension. While cycle
count and energy consumption should also be considered, we can be pretty
certain that implementing clear_page() with the Zicboz extension is a win
by comparing the new dynamic instruction count with its current count[1].
Doing so we see that the new count is just over a quarter of the old count
(see patch6's commit message for more details).
For those of you who reviewed v1[2], you may be looking for the memset()
patches. As pointed out in v1, and a couple follow-up emails, it's not
clear that patching memset() is a win yet. When I get a chance to test
on real hardware with a comprehensive benchmark collection then I can
post the memset() patches separately (assuming the benchmarks show it's
worthwhile).
* b4-shazam-merge:
RISC-V: KVM: Expose Zicboz to the guest
RISC-V: KVM: Provide UAPI for Zicboz block size
RISC-V: Use Zicboz in clear_page when available
RISC-V: cpufeatures: Put the upper 16 bits of patch ID to work
RISC-V: Add Zicboz detection and block size parsing
dt-bindings: riscv: Document cboz-block-size
RISC-V: Factor out body of riscv_init_cbom_blocksize loop
RISC-V: alternatives: Support patching multiple insns in assembly
Link: https://lore.kernel.org/r/20230224162631.405473-1-ajones@ventanamicro.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
Guests may use the cbo.zero instruction when the CPU has the Zicboz
extension and the hypervisor sets henvcfg.CBZE.
Add Zicboz support for KVM guests which may be enabled and
disabled from KVM userspace using the ISA extension ONE_REG API.
Signed-off-by: Andrew Jones <ajones@ventanamicro.com>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
Link: https://lore.kernel.org/r/20230224162631.405473-9-ajones@ventanamicro.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
We're about to allow guests to use the Zicboz extension. KVM
userspace needs to know the cache block size in order to
properly advertise it to the guest. Provide a virtual config
register for userspace to get it with the GET_ONE_REG API, but
setting it cannot be supported, so disallow SET_ONE_REG.
Signed-off-by: Andrew Jones <ajones@ventanamicro.com>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
Link: https://lore.kernel.org/r/20230224162631.405473-8-ajones@ventanamicro.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
Using memset() to zero a 4K page takes 563 total instructions, where
20 are branches. clear_page(), with Zicboz and a 64 byte block size,
takes 169 total instructions, where 4 are branches and 33 are nops.
Even though the block size is a variable, thanks to alternatives, we
can still implement a Duff device without having to do any preliminary
calculations. This is achieved by using the alternatives' cpufeature
value (the upper 16 bits of patch_id). The value used is the maximum
zicboz block size order accepted at the patch site. This enables us
to stop patching / unrolling when 4K bytes have been zeroed (we would
loop and continue after 4K if the page size would be larger)
For 4K pages, unrolling 16 times allows block sizes of 64 and 128 to
only loop a few times and larger block sizes to not loop at all. Since
cbo.zero doesn't take an offset, we also need an 'add' after each
instruction, making the loop body 112 to 160 bytes. Hopefully this
is small enough to not cause icache misses.
Signed-off-by: Andrew Jones <ajones@ventanamicro.com>
Acked-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20230224162631.405473-7-ajones@ventanamicro.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
Conor Dooley