From: Palmer Dabbelt <palmerdabbelt@google.com>
To: greentime.hu@sifive.com
Cc: Paul Walmsley <paul.walmsley@sifive.com>,
linux-kernel@vger.kernel.org, green.hu@gmail.com,
greentime@kernel.org, greentime.hu@sifive.com,
linux-riscv@lists.infradead.org
Subject: Re: [PATCH] riscv: set pmp configuration if kernel is running in M-mode
Date: Wed, 29 Jan 2020 11:23:26 -0800 (PST) [thread overview]
Message-ID: <mhng-f4b42a19-22f3-43f3-9750-58b994e23246@palmerdabbelt-glaptop1> (raw)
In-Reply-To: <20200109031740.29717-1-greentime.hu@sifive.com>
On Thu, 09 Jan 2020 03:17:40 GMT (+0000), greentime.hu@sifive.com wrote:
> When the kernel is running in S-mode, the expectation is that the
> bootloader or SBI layer will configure the PMP to allow the kernel to
> access physical memory. But, when the kernel is running in M-mode and is
> started with the ELF "loader", there's probably no bootloader or SBI layer
> involved to configure the PMP. Thus, we need to configure the PMP
> ourselves to enable the kernel to access all regions.
>
> Signed-off-by: Greentime Hu <greentime.hu@sifive.com>
> ---
> arch/riscv/include/asm/csr.h | 12 ++++++++++++
> arch/riscv/kernel/head.S | 6 ++++++
> 2 files changed, 18 insertions(+)
>
> diff --git a/arch/riscv/include/asm/csr.h b/arch/riscv/include/asm/csr.h
> index 0a62d2d68455..0f25e6c4e45c 100644
> --- a/arch/riscv/include/asm/csr.h
> +++ b/arch/riscv/include/asm/csr.h
> @@ -72,6 +72,16 @@
> #define EXC_LOAD_PAGE_FAULT 13
> #define EXC_STORE_PAGE_FAULT 15
>
> +/* PMP configuration */
> +#define PMP_R 0x01
> +#define PMP_W 0x02
> +#define PMP_X 0x04
> +#define PMP_A 0x18
> +#define PMP_A_TOR 0x08
> +#define PMP_A_NA4 0x10
> +#define PMP_A_NAPOT 0x18
> +#define PMP_L 0x80
> +
> /* symbolic CSR names: */
> #define CSR_CYCLE 0xc00
> #define CSR_TIME 0xc01
> @@ -100,6 +110,8 @@
> #define CSR_MCAUSE 0x342
> #define CSR_MTVAL 0x343
> #define CSR_MIP 0x344
> +#define CSR_PMPCFG0 0x3a0
> +#define CSR_PMPADDR0 0x3b0
> #define CSR_MHARTID 0xf14
>
> #ifdef CONFIG_RISCV_M_MODE
> diff --git a/arch/riscv/kernel/head.S b/arch/riscv/kernel/head.S
> index 5c8b24bf4e4e..f8f996916c5b 100644
> --- a/arch/riscv/kernel/head.S
> +++ b/arch/riscv/kernel/head.S
> @@ -60,6 +60,12 @@ _start_kernel:
> /* Reset all registers except ra, a0, a1 */
> call reset_regs
>
> + /* Setup a PMP to permit access to all of memory. */
> + li a0, -1
> + csrw CSR_PMPADDR0, a0
> + li a0, (PMP_A_NAPOT | PMP_R | PMP_W | PMP_X)
> + csrw CSR_PMPCFG0, a0
These should be guarded by some sort of #ifdef CONFIG_M_MODE, as they're not
part of S mode.
> +
> /*
> * The hartid in a0 is expected later on, and we have no firmware
> * to hand it to us.
next prev parent reply other threads:[~2020-01-29 19:23 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-09 3:17 [PATCH] riscv: set pmp configuration if kernel is running in M-mode Greentime Hu
2020-01-29 19:23 ` Palmer Dabbelt [this message]
2020-01-30 2:38 ` Greentime Hu
2020-02-10 17:59 ` Palmer Dabbelt
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=mhng-f4b42a19-22f3-43f3-9750-58b994e23246@palmerdabbelt-glaptop1 \
--to=palmerdabbelt@google.com \
--cc=green.hu@gmail.com \
--cc=greentime.hu@sifive.com \
--cc=greentime@kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-riscv@lists.infradead.org \
--cc=paul.walmsley@sifive.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).