[RFC PATCH V3 00/11] riscv: Add vector ISA support

guoren
2020-03-08T09:50:35Z

The implementation follow the RISC-V "V" Vector Extension draft v0.8 with
128bit-vlen and it's based on linux-5.6-rc3 and tested with qemu [1].

The patch implement basic context switch, sigcontext save/restore and
ptrace interface with a new regset NT_RISCV_VECTOR. Only fixed 128bit-vlen
is implemented. We need to discuss about vlen-size for libc sigcontext and
ptrace (the maximum size of vlen is unlimited in spec).

Puzzle:
Dave Martin has talked "Growing CPU register state without breaking ABI" [2]
before, and riscv also met vlen size problem. Let's discuss the common issue
for all architectures and we need a better solution for unlimited vlen.

Any help are welcomed :)

1: https://github.com/romanheros/qemu.git branch:vector-upstream-v3
2: https://blog.linuxplumbersconf.org/2017/ocw/sessions/4671.html

---
Changelog V3
- Rebase linux-5.6-rc3 and tested with qemu
- Seperate patches with Anup's advice
- Give out a ABI puzzle with unlimited vlen

Changelog V2
- Fixup typo "vecotr, fstate_save->vstate_save".
- Fixup wrong saved registers' length in vector.S.
- Seperate unrelated patches from this one.

Guo Ren (11):
riscv: Separate patch for cflags and aflags
riscv: Rename __switch_to_aux -> fpu
riscv: Extending cpufeature.c to detect V-extension
riscv: Add CSR defines related to VECTOR extension
riscv: Add vector feature to compile
riscv: Add has_vector detect
riscv: Reset vector register
riscv: Add vector struct and assembler definitions
riscv: Add task switch support for VECTOR
riscv: Add ptrace support
riscv: Add sigcontext save/restore

arch/riscv/Kconfig | 9 ++
arch/riscv/Makefile | 19 ++-
arch/riscv/include/asm/csr.h | 17 ++-
arch/riscv/include/asm/processor.h | 1 +
arch/riscv/include/asm/switch_to.h | 54 ++++++-
arch/riscv/include/uapi/asm/elf.h | 1 +
arch/riscv/include/uapi/asm/hwcap.h | 1 +
arch/riscv/include/uapi/asm/ptrace.h | 9 ++
arch/riscv/include/uapi/asm/sigcontext.h | 1 +
arch/riscv/kernel/Makefile | 1 +
arch/riscv/kernel/asm-offsets.c | 187 +++++++++++++++++++++++
arch/riscv/kernel/cpufeature.c | 12 +-
arch/riscv/kernel/entry.S | 2 +-
arch/riscv/kernel/head.S | 49 +++++-
arch/riscv/kernel/process.c | 10 ++
arch/riscv/kernel/ptrace.c | 41 +++++
arch/riscv/kernel/signal.c | 40 +++++
arch/riscv/kernel/vector.S | 84 ++++++++++
include/uapi/linux/elf.h | 1 +
19 files changed, 524 insertions(+), 15 deletions(-)
create mode 100644 arch/riscv/kernel/vector.S

--
2.17.0