From: Anup Patel anup.patel@wdc.com
euleros inclusion category: feature bugzilla: NA CVE: NA
This patch adds riscv_isa bitmap which represents Host ISA features common across all Host CPUs. The riscv_isa is not same as elf_hwcap because elf_hwcap will only have ISA features relevant for user-space apps whereas riscv_isa will have ISA features relevant to both kernel and user-space apps.
One of the use-case for riscv_isa bitmap is in KVM hypervisor where we will use it to do following operations:
1. Check whether hypervisor extension is available 2. Find ISA features that need to be virtualized (e.g. floating point support, vector extension, etc.)
Link: https://gitee.com/openeuler/kernel/issues/I1RR1Y Signed-off-by: Anup Patel anup.patel@wdc.com Signed-off-by: Atish Patra atish.patra@wdc.com Reviewed-by: Alexander Graf graf@amazon.com Signed-off-by: Mingwang Li limingwang@huawei.com Reviewed-by: Yifei Jiang jiangyifei@huawei.com Signed-off-by: Xie XiuQi xiexiuqi@huawei.com --- arch/riscv/include/asm/hwcap.h | 22 +++++++++ arch/riscv/kernel/cpufeature.c | 83 ++++++++++++++++++++++++++++++++-- 2 files changed, 102 insertions(+), 3 deletions(-)
diff --git a/arch/riscv/include/asm/hwcap.h b/arch/riscv/include/asm/hwcap.h index 1bb0cd04aec3..5589c012e004 100644 --- a/arch/riscv/include/asm/hwcap.h +++ b/arch/riscv/include/asm/hwcap.h @@ -8,6 +8,7 @@ #ifndef _ASM_RISCV_HWCAP_H #define _ASM_RISCV_HWCAP_H
+#include <linux/bits.h> #include <uapi/asm/hwcap.h>
#ifndef __ASSEMBLY__ @@ -22,6 +23,27 @@ enum { };
extern unsigned long elf_hwcap; + +#define RISCV_ISA_EXT_a ('a' - 'a') +#define RISCV_ISA_EXT_c ('c' - 'a') +#define RISCV_ISA_EXT_d ('d' - 'a') +#define RISCV_ISA_EXT_f ('f' - 'a') +#define RISCV_ISA_EXT_h ('h' - 'a') +#define RISCV_ISA_EXT_i ('i' - 'a') +#define RISCV_ISA_EXT_m ('m' - 'a') +#define RISCV_ISA_EXT_s ('s' - 'a') +#define RISCV_ISA_EXT_u ('u' - 'a') + +#define RISCV_ISA_EXT_MAX 256 + +unsigned long riscv_isa_extension_base(const unsigned long *isa_bitmap); + +#define riscv_isa_extension_mask(ext) BIT_MASK(RISCV_ISA_EXT_##ext) + +bool __riscv_isa_extension_available(const unsigned long *isa_bitmap, int bit); +#define riscv_isa_extension_available(isa_bitmap, ext) \ + __riscv_isa_extension_available(isa_bitmap, RISCV_ISA_EXT_##ext) + #endif
#endif /* _ASM_RISCV_HWCAP_H */ diff --git a/arch/riscv/kernel/cpufeature.c b/arch/riscv/kernel/cpufeature.c index a5ad00043104..ac202f44a670 100644 --- a/arch/riscv/kernel/cpufeature.c +++ b/arch/riscv/kernel/cpufeature.c @@ -6,6 +6,7 @@ * Copyright (C) 2017 SiFive */
+#include <linux/bitmap.h> #include <linux/of.h> #include <asm/processor.h> #include <asm/hwcap.h> @@ -13,15 +14,57 @@ #include <asm/switch_to.h>
unsigned long elf_hwcap __read_mostly; + +/* Host ISA bitmap */ +static DECLARE_BITMAP(riscv_isa, RISCV_ISA_EXT_MAX) __read_mostly; + #ifdef CONFIG_FPU bool has_fpu __read_mostly; #endif
+/** + * riscv_isa_extension_base() - Get base extension word + * + * @isa_bitmap: ISA bitmap to use + * Return: base extension word as unsigned long value + * + * NOTE: If isa_bitmap is NULL then Host ISA bitmap will be used. + */ +unsigned long riscv_isa_extension_base(const unsigned long *isa_bitmap) +{ + if (!isa_bitmap) + return riscv_isa[0]; + return isa_bitmap[0]; +} +EXPORT_SYMBOL_GPL(riscv_isa_extension_base); + +/** + * __riscv_isa_extension_available() - Check whether given extension + * is available or not + * + * @isa_bitmap: ISA bitmap to use + * @bit: bit position of the desired extension + * Return: true or false + * + * NOTE: If isa_bitmap is NULL then Host ISA bitmap will be used. + */ +bool __riscv_isa_extension_available(const unsigned long *isa_bitmap, int bit) +{ + const unsigned long *bmap = (isa_bitmap) ? isa_bitmap : riscv_isa; + + if (bit >= RISCV_ISA_EXT_MAX) + return false; + + return test_bit(bit, bmap) ? true : false; +} +EXPORT_SYMBOL_GPL(__riscv_isa_extension_available); + void riscv_fill_hwcap(void) { struct device_node *node; const char *isa; - size_t i; + char print_str[BITS_PER_LONG + 1]; + size_t i, j, isa_len; static unsigned long isa2hwcap[256] = {0};
isa2hwcap['i'] = isa2hwcap['I'] = COMPAT_HWCAP_ISA_I; @@ -33,8 +76,11 @@ void riscv_fill_hwcap(void)
elf_hwcap = 0;
+ bitmap_zero(riscv_isa, RISCV_ISA_EXT_MAX); + for_each_of_cpu_node(node) { unsigned long this_hwcap = 0; + unsigned long this_isa = 0;
if (riscv_of_processor_hartid(node) < 0) continue; @@ -44,8 +90,24 @@ void riscv_fill_hwcap(void) continue; }
- for (i = 0; i < strlen(isa); ++i) + i = 0; + isa_len = strlen(isa); +#if IS_ENABLED(CONFIG_32BIT) + if (!strncmp(isa, "rv32", 4)) + i += 4; +#elif IS_ENABLED(CONFIG_64BIT) + if (!strncmp(isa, "rv64", 4)) + i += 4; +#endif + for (; i < isa_len; ++i) { this_hwcap |= isa2hwcap[(unsigned char)(isa[i])]; + /* + * TODO: X, Y and Z extension parsing for Host ISA + * bitmap will be added in-future. + */ + if ('a' <= isa[i] && isa[i] < 'x') + this_isa |= (1UL << (isa[i] - 'a')); + }
/* * All "okay" hart should have same isa. Set HWCAP based on @@ -56,6 +118,11 @@ void riscv_fill_hwcap(void) elf_hwcap &= this_hwcap; else elf_hwcap = this_hwcap; + + if (riscv_isa[0]) + riscv_isa[0] &= this_isa; + else + riscv_isa[0] = this_isa; }
/* We don't support systems with F but without D, so mask those out @@ -65,7 +132,17 @@ void riscv_fill_hwcap(void) elf_hwcap &= ~COMPAT_HWCAP_ISA_F; }
- pr_info("elf_hwcap is 0x%lx\n", elf_hwcap); + memset(print_str, 0, sizeof(print_str)); + for (i = 0, j = 0; i < BITS_PER_LONG; i++) + if (riscv_isa[0] & BIT_MASK(i)) + print_str[j++] = (char)('a' + i); + pr_info("riscv: ISA extensions %s\n", print_str); + + memset(print_str, 0, sizeof(print_str)); + for (i = 0, j = 0; i < BITS_PER_LONG; i++) + if (elf_hwcap & BIT_MASK(i)) + print_str[j++] = (char)('a' + i); + pr_info("riscv: ELF capabilities %s\n", print_str);
#ifdef CONFIG_FPU if (elf_hwcap & (COMPAT_HWCAP_ISA_F | COMPAT_HWCAP_ISA_D))