From: Conor Dooley <conor@kernel.org>
To: Andy Chiu <andy.chiu@sifive.com>
Cc: linux-riscv@lists.infradead.org, palmer@dabbelt.com,
anup@brainfault.org, atishp@atishpatra.org,
kvm-riscv@lists.infradead.org, kvm@vger.kernel.org,
vineetg@rivosinc.com, greentime.hu@sifive.com,
guoren@linux.alibaba.com, Eric Biederman <ebiederm@xmission.com>,
Kees Cook <keescook@chromium.org>,
Paul Walmsley <paul.walmsley@sifive.com>,
Albert Ou <aou@eecs.berkeley.edu>,
Conor Dooley <conor.dooley@microchip.com>,
Heiko Stuebner <heiko.stuebner@vrull.eu>,
Vincent Chen <vincent.chen@sifive.com>,
Andrew Jones <ajones@ventanamicro.com>,
Anup Patel <apatel@ventanamicro.com>,
Jisheng Zhang <jszhang@kernel.org>, Guo Ren <guoren@kernel.org>
Subject: Re: [PATCH -next v21 20/27] riscv: hwcap: change ELF_HWCAP to a function
Date: Mon, 5 Jun 2023 17:24:53 +0100 [thread overview]
Message-ID: <20230605-embattled-navigator-408a7b60b2ab@spud> (raw)
In-Reply-To: <20230605110724.21391-21-andy.chiu@sifive.com>
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On Mon, Jun 05, 2023 at 11:07:17AM +0000, Andy Chiu wrote:
> Using a function is flexible to represent ELF_HWCAP. So the kernel may
> encode hwcap reflecting supported hardware features just at the moment of
> the start of each program.
>
> This will be helpful when we introduce prctl/sysctl interface to control
> per-process availability of Vector extension in following patches.
> Programs started with V disabled should see V masked off in theirs
> ELF_HWCAP.
For the uninformed, like myself, this needs to be a function, rather
than open coding the masking of the V bit at the one user of ELF_HWCAP
this series adds, because the binfmt stuff needs to get the value in
create_elf_fdpic_tables() & co?
If that's your purpose,
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
One minor comment below.
>
> Signed-off-by: Andy Chiu <andy.chiu@sifive.com>
> ---
> arch/riscv/include/asm/elf.h | 2 +-
> arch/riscv/include/asm/hwcap.h | 2 ++
> arch/riscv/kernel/cpufeature.c | 5 +++++
> 3 files changed, 8 insertions(+), 1 deletion(-)
>
> diff --git a/arch/riscv/include/asm/elf.h b/arch/riscv/include/asm/elf.h
> index ca23c4f6c440..c24280774caf 100644
> --- a/arch/riscv/include/asm/elf.h
> +++ b/arch/riscv/include/asm/elf.h
> @@ -66,7 +66,7 @@ extern bool compat_elf_check_arch(Elf32_Ehdr *hdr);
> * via a bitmap that coorespends to each single-letter ISA extension. This is
> * essentially defunct, but will remain for compatibility with userspace.
> */
> -#define ELF_HWCAP (elf_hwcap & ((1UL << RISCV_ISA_EXT_BASE) - 1))
> +#define ELF_HWCAP riscv_get_elf_hwcap()
> extern unsigned long elf_hwcap;
>
> /*
> diff --git a/arch/riscv/include/asm/hwcap.h b/arch/riscv/include/asm/hwcap.h
> index 574385930ba7..e6c288ac4581 100644
> --- a/arch/riscv/include/asm/hwcap.h
> +++ b/arch/riscv/include/asm/hwcap.h
> @@ -61,6 +61,8 @@
>
> #include <linux/jump_label.h>
>
> +unsigned long riscv_get_elf_hwcap(void);
> +
> struct riscv_isa_ext_data {
> /* Name of the extension displayed to userspace via /proc/cpuinfo */
> char uprop[RISCV_ISA_EXT_NAME_LEN_MAX];
> diff --git a/arch/riscv/kernel/cpufeature.c b/arch/riscv/kernel/cpufeature.c
> index 28032b083463..29c0680652a0 100644
> --- a/arch/riscv/kernel/cpufeature.c
> +++ b/arch/riscv/kernel/cpufeature.c
> @@ -293,6 +293,11 @@ void __init riscv_fill_hwcap(void)
> pr_info("riscv: ELF capabilities %s\n", print_str);
> }
>
> +unsigned long riscv_get_elf_hwcap(void)
> +{
> + return (elf_hwcap & ((1UL << RISCV_ISA_EXT_BASE) - 1));
If you respin for some other reason, could you drop the open coded mask
creation as part of these changes?
Cheers,
Conor.
> +}
> +
> #ifdef CONFIG_RISCV_ALTERNATIVE
> /*
> * Alternative patch sites consider 48 bits when determining when to patch
> --
> 2.17.1
>
>
> _______________________________________________
> linux-riscv mailing list
> linux-riscv@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-riscv
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next prev parent reply other threads:[~2023-06-05 16:25 UTC|newest]
Thread overview: 53+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-06-05 11:06 [PATCH -next v21 00/27] riscv: Add vector ISA support Andy Chiu
2023-06-05 11:06 ` [PATCH -next v21 01/27] riscv: Rename __switch_to_aux() -> fpu Andy Chiu
2023-06-05 11:06 ` [PATCH -next v21 02/27] riscv: Extending cpufeature.c to detect V-extension Andy Chiu
2023-06-05 11:07 ` [PATCH -next v21 03/27] riscv: hwprobe: Add support for probing V in RISCV_HWPROBE_KEY_IMA_EXT_0 Andy Chiu
2023-06-08 12:36 ` Heiko Stübner
2023-06-28 0:30 ` Stefan O'Rear
2023-06-28 1:56 ` Palmer Dabbelt
2023-06-28 4:53 ` Stefan O'Rear
2023-06-05 11:07 ` [PATCH -next v21 04/27] riscv: Add new csr defines related to vector extension Andy Chiu
2023-06-05 11:07 ` [PATCH -next v21 05/27] riscv: Clear vector regfile on bootup Andy Chiu
2023-06-05 11:07 ` [PATCH -next v21 06/27] riscv: Disable Vector Instructions for kernel itself Andy Chiu
2023-06-05 11:07 ` [PATCH -next v21 07/27] riscv: Introduce Vector enable/disable helpers Andy Chiu
2023-06-05 11:07 ` [PATCH -next v21 08/27] riscv: Introduce riscv_v_vsize to record size of Vector context Andy Chiu
2023-06-05 11:07 ` [PATCH -next v21 09/27] riscv: Introduce struct/helpers to save/restore per-task Vector state Andy Chiu
2023-06-12 14:32 ` Rémi Denis-Courmont
2023-06-13 14:19 ` Andy Chiu
2023-06-05 11:07 ` [PATCH -next v21 10/27] riscv: Add task switch support for vector Andy Chiu
2023-06-05 11:07 ` [PATCH -next v21 11/27] riscv: Allocate user's vector context in the first-use trap Andy Chiu
2023-06-05 16:04 ` Conor Dooley
2023-06-08 13:58 ` Heiko Stübner
2023-06-05 11:07 ` [PATCH -next v21 12/27] riscv: Add ptrace vector support Andy Chiu
2023-06-05 11:07 ` [PATCH -next v21 13/27] riscv: signal: check fp-reserved words unconditionally Andy Chiu
2023-06-05 11:07 ` [PATCH -next v21 14/27] riscv: signal: Add sigcontext save/restore for vector Andy Chiu
2023-10-08 9:19 ` Aurelien Jarno
2023-10-08 16:23 ` Andy Chiu
2023-10-09 17:08 ` Aurelien Jarno
2023-06-05 11:07 ` [PATCH -next v21 15/27] riscv: signal: Report signal frame size to userspace via auxv Andy Chiu
2023-06-05 11:07 ` [PATCH -next v21 16/27] riscv: signal: validate altstack to reflect Vector Andy Chiu
2023-06-05 11:07 ` [PATCH -next v21 17/27] riscv: prevent stack corruption by reserving task_pt_regs(p) early Andy Chiu
2023-06-05 11:07 ` [PATCH -next v21 18/27] riscv: kvm: Add V extension to KVM ISA Andy Chiu
2023-06-05 11:07 ` [PATCH -next v21 19/27] riscv: KVM: Add vector lazy save/restore support Andy Chiu
2023-06-05 11:07 ` [PATCH -next v21 20/27] riscv: hwcap: change ELF_HWCAP to a function Andy Chiu
2023-06-05 16:24 ` Conor Dooley [this message]
2023-06-12 14:36 ` Rémi Denis-Courmont
2023-06-12 15:30 ` Conor Dooley
2023-06-05 11:07 ` [PATCH -next v21 21/27] riscv: Add prctl controls for userspace vector management Andy Chiu
2023-06-05 11:07 ` [PATCH -next v21 22/27] riscv: Add sysctl to set the default vector rule for new processes Andy Chiu
2023-06-05 11:07 ` [PATCH -next v21 23/27] riscv: detect assembler support for .option arch Andy Chiu
2023-06-05 15:48 ` Nathan Chancellor
2023-06-05 16:25 ` Conor Dooley
2024-01-21 1:13 ` Eric Biggers
2024-01-21 2:55 ` Palmer Dabbelt
2024-01-21 14:32 ` Andy Chiu
2024-01-21 18:10 ` Eric Biggers
2024-01-22 22:29 ` Nathan Chancellor
2024-01-24 21:58 ` Eric Biggers
2023-06-05 11:07 ` [PATCH -next v21 24/27] riscv: Enable Vector code to be built Andy Chiu
2023-06-05 11:07 ` [PATCH -next v21 25/27] riscv: Add documentation for Vector Andy Chiu
2023-06-12 14:40 ` Rémi Denis-Courmont
2023-06-05 11:07 ` [PATCH -next v21 26/27] selftests: Test RISC-V Vector prctl interface Andy Chiu
2023-06-05 11:07 ` [PATCH -next v21 27/27] selftests: add .gitignore file for RISC-V hwprobe Andy Chiu
2023-06-09 14:00 ` [PATCH -next v21 00/27] riscv: Add vector ISA support Palmer Dabbelt
2023-06-09 14:50 ` patchwork-bot+linux-riscv
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