diff mbox series

[V5,12/21] riscv: compat: syscall: Add entry.S implementation

Message ID 20220201150545.1512822-13-guoren@kernel.org
State New
Headers show
Series riscv: compat: Add COMPAT mode support for rv64 | expand

Commit Message

Guo Ren Feb. 1, 2022, 3:05 p.m. UTC
From: Guo Ren <guoren@linux.alibaba.com>

Implement the entry of compat_sys_call_table[] in asm. Ref to
riscv-privileged spec 4.1.1 Supervisor Status Register (sstatus):

 BIT[32:33] = UXL[1:0]:
 - 1:32
 - 2:64
 - 3:128

Signed-off-by: Guo Ren <guoren@linux.alibaba.com>
Signed-off-by: Guo Ren <guoren@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
---
 arch/riscv/include/asm/csr.h |  7 +++++++
 arch/riscv/kernel/entry.S    | 18 ++++++++++++++++--
 2 files changed, 23 insertions(+), 2 deletions(-)

Comments

Palmer Dabbelt Feb. 23, 2022, 1:42 a.m. UTC | #1
On Tue, 01 Feb 2022 07:05:36 PST (-0800), guoren@kernel.org wrote:
> From: Guo Ren <guoren@linux.alibaba.com>
>
> Implement the entry of compat_sys_call_table[] in asm. Ref to
> riscv-privileged spec 4.1.1 Supervisor Status Register (sstatus):
>
>  BIT[32:33] = UXL[1:0]:
>  - 1:32
>  - 2:64
>  - 3:128
>
> Signed-off-by: Guo Ren <guoren@linux.alibaba.com>
> Signed-off-by: Guo Ren <guoren@kernel.org>
> Cc: Arnd Bergmann <arnd@arndb.de>
> Cc: Palmer Dabbelt <palmer@dabbelt.com>
> ---
>  arch/riscv/include/asm/csr.h |  7 +++++++
>  arch/riscv/kernel/entry.S    | 18 ++++++++++++++++--
>  2 files changed, 23 insertions(+), 2 deletions(-)
>
> diff --git a/arch/riscv/include/asm/csr.h b/arch/riscv/include/asm/csr.h
> index ae711692eec9..eed96fa62d66 100644
> --- a/arch/riscv/include/asm/csr.h
> +++ b/arch/riscv/include/asm/csr.h
> @@ -36,6 +36,13 @@
>  #define SR_SD		_AC(0x8000000000000000, UL) /* FS/XS dirty */
>  #endif
>
> +#ifdef CONFIG_COMPAT
> +#define SR_UXL		_AC(0x300000000, UL) /* XLEN mask for U-mode */
> +#define SR_UXL_32	_AC(0x100000000, UL) /* XLEN = 32 for U-mode */
> +#define SR_UXL_64	_AC(0x200000000, UL) /* XLEN = 64 for U-mode */
> +#define SR_UXL_SHIFT	32
> +#endif
> +
>  /* SATP flags */
>  #ifndef CONFIG_64BIT
>  #define SATP_PPN	_AC(0x003FFFFF, UL)
> diff --git a/arch/riscv/kernel/entry.S b/arch/riscv/kernel/entry.S
> index ed29e9c8f660..1951743f09b3 100644
> --- a/arch/riscv/kernel/entry.S
> +++ b/arch/riscv/kernel/entry.S
> @@ -207,13 +207,27 @@ check_syscall_nr:
>  	 * Syscall number held in a7.
>  	 * If syscall number is above allowed value, redirect to ni_syscall.
>  	 */
> -	bgeu a7, t0, 1f
> +	bgeu a7, t0, 3f
> +#ifdef CONFIG_COMPAT
> +	REG_L s0, PT_STATUS(sp)
> +	srli s0, s0, SR_UXL_SHIFT
> +	andi s0, s0, (SR_UXL >> SR_UXL_SHIFT)
> +	li t0, (SR_UXL_32 >> SR_UXL_SHIFT)
> +	sub t0, s0, t0
> +	bnez t0, 1f
> +
> +	/* Call compat_syscall */
> +	la s0, compat_sys_call_table
> +	j 2f
> +1:
> +#endif
>  	/* Call syscall */
>  	la s0, sys_call_table
> +2:
>  	slli t0, a7, RISCV_LGPTR
>  	add s0, s0, t0
>  	REG_L s0, 0(s0)
> -1:
> +3:
>  	jalr s0
>
>  ret_from_syscall:

Reviewed-by: Palmer Dabbelt <palmer@rivosinc.com>
diff mbox series

Patch

diff --git a/arch/riscv/include/asm/csr.h b/arch/riscv/include/asm/csr.h
index ae711692eec9..eed96fa62d66 100644
--- a/arch/riscv/include/asm/csr.h
+++ b/arch/riscv/include/asm/csr.h
@@ -36,6 +36,13 @@ 
 #define SR_SD		_AC(0x8000000000000000, UL) /* FS/XS dirty */
 #endif
 
+#ifdef CONFIG_COMPAT
+#define SR_UXL		_AC(0x300000000, UL) /* XLEN mask for U-mode */
+#define SR_UXL_32	_AC(0x100000000, UL) /* XLEN = 32 for U-mode */
+#define SR_UXL_64	_AC(0x200000000, UL) /* XLEN = 64 for U-mode */
+#define SR_UXL_SHIFT	32
+#endif
+
 /* SATP flags */
 #ifndef CONFIG_64BIT
 #define SATP_PPN	_AC(0x003FFFFF, UL)
diff --git a/arch/riscv/kernel/entry.S b/arch/riscv/kernel/entry.S
index ed29e9c8f660..1951743f09b3 100644
--- a/arch/riscv/kernel/entry.S
+++ b/arch/riscv/kernel/entry.S
@@ -207,13 +207,27 @@  check_syscall_nr:
 	 * Syscall number held in a7.
 	 * If syscall number is above allowed value, redirect to ni_syscall.
 	 */
-	bgeu a7, t0, 1f
+	bgeu a7, t0, 3f
+#ifdef CONFIG_COMPAT
+	REG_L s0, PT_STATUS(sp)
+	srli s0, s0, SR_UXL_SHIFT
+	andi s0, s0, (SR_UXL >> SR_UXL_SHIFT)
+	li t0, (SR_UXL_32 >> SR_UXL_SHIFT)
+	sub t0, s0, t0
+	bnez t0, 1f
+
+	/* Call compat_syscall */
+	la s0, compat_sys_call_table
+	j 2f
+1:
+#endif
 	/* Call syscall */
 	la s0, sys_call_table
+2:
 	slli t0, a7, RISCV_LGPTR
 	add s0, s0, t0
 	REG_L s0, 0(s0)
-1:
+3:
 	jalr s0
 
 ret_from_syscall: