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ff689fd21c
Svpbmt (the S should be capitalized) is the
"Supervisor-mode: page-based memory types" extension
that specifies attributes for cacheability, idempotency
and ordering.
The relevant settings are done in special bits in PTEs:
Here is the svpbmt PTE format:
| 63 | 62-61 | 60-8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0
N MT RSW D A G U X W R V
^
Of the Reserved bits [63:54] in a leaf PTE, the high bit is already
allocated (as the N bit), so bits [62:61] are used as the MT (aka
MemType) field. This field specifies one of three memory types that
are close equivalents (or equivalent in effect) to the three main x86
and ARMv8 memory types - as shown in the following table.
RISC-V
Encoding &
MemType RISC-V Description
---------- ------------------------------------------------
00 - PMA Normal Cacheable, No change to implied PMA memory type
01 - NC Non-cacheable, idempotent, weakly-ordered Main Memory
10 - IO Non-cacheable, non-idempotent, strongly-ordered I/O memory
11 - Rsvd Reserved for future standard use
As the extension will not be present on all implementations,
implement a method to handle cpufeatures via alternatives
to not incur runtime penalties on cpu variants not supporting
specific extensions and patch relevant code parts at runtime.
Co-developed-by: Wei Fu <wefu@redhat.com>
Signed-off-by: Wei Fu <wefu@redhat.com>
Co-developed-by: Liu Shaohua <liush@allwinnertech.com>
Signed-off-by: Liu Shaohua <liush@allwinnertech.com>
Co-developed-by: Guo Ren <guoren@kernel.org>
Signed-off-by: Guo Ren <guoren@kernel.org>
[moved to use the alternatives mechanism]
Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Reviewed-by: Philipp Tomsich <philipp.tomsich@vrull.eu>
Link: https://lore.kernel.org/r/20220511192921.2223629-10-heiko@sntech.de
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
76 lines
2.1 KiB
C
76 lines
2.1 KiB
C
/* SPDX-License-Identifier: GPL-2.0-only */
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/*
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* Copied from arch/arm64/include/asm/hwcap.h
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*
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* Copyright (C) 2012 ARM Ltd.
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* Copyright (C) 2017 SiFive
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*/
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#ifndef _ASM_RISCV_HWCAP_H
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#define _ASM_RISCV_HWCAP_H
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#include <linux/bits.h>
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#include <uapi/asm/hwcap.h>
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#ifndef __ASSEMBLY__
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/*
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* This yields a mask that user programs can use to figure out what
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* instruction set this cpu supports.
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*/
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#define ELF_HWCAP (elf_hwcap)
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enum {
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CAP_HWCAP = 1,
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};
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extern unsigned long elf_hwcap;
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#define RISCV_ISA_EXT_a ('a' - 'a')
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#define RISCV_ISA_EXT_c ('c' - 'a')
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#define RISCV_ISA_EXT_d ('d' - 'a')
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#define RISCV_ISA_EXT_f ('f' - 'a')
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#define RISCV_ISA_EXT_h ('h' - 'a')
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#define RISCV_ISA_EXT_i ('i' - 'a')
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#define RISCV_ISA_EXT_m ('m' - 'a')
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#define RISCV_ISA_EXT_s ('s' - 'a')
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#define RISCV_ISA_EXT_u ('u' - 'a')
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/*
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* Increse this to higher value as kernel support more ISA extensions.
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*/
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#define RISCV_ISA_EXT_MAX 64
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#define RISCV_ISA_EXT_NAME_LEN_MAX 32
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/* The base ID for multi-letter ISA extensions */
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#define RISCV_ISA_EXT_BASE 26
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/*
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* This enum represent the logical ID for each multi-letter RISC-V ISA extension.
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* The logical ID should start from RISCV_ISA_EXT_BASE and must not exceed
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* RISCV_ISA_EXT_MAX. 0-25 range is reserved for single letter
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* extensions while all the multi-letter extensions should define the next
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* available logical extension id.
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*/
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enum riscv_isa_ext_id {
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RISCV_ISA_EXT_SSCOFPMF = RISCV_ISA_EXT_BASE,
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RISCV_ISA_EXT_SVPBMT,
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RISCV_ISA_EXT_ID_MAX = RISCV_ISA_EXT_MAX,
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};
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struct riscv_isa_ext_data {
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/* Name of the extension displayed to userspace via /proc/cpuinfo */
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char uprop[RISCV_ISA_EXT_NAME_LEN_MAX];
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/* The logical ISA extension ID */
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unsigned int isa_ext_id;
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};
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unsigned long riscv_isa_extension_base(const unsigned long *isa_bitmap);
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#define riscv_isa_extension_mask(ext) BIT_MASK(RISCV_ISA_EXT_##ext)
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bool __riscv_isa_extension_available(const unsigned long *isa_bitmap, int bit);
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#define riscv_isa_extension_available(isa_bitmap, ext) \
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__riscv_isa_extension_available(isa_bitmap, RISCV_ISA_EXT_##ext)
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#endif
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#endif /* _ASM_RISCV_HWCAP_H */
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