On Tue, 01 Feb 2022 07:05:36 PST (-0800), guoren@xxxxxxxxxx wrote:
From: Guo Ren <guoren@xxxxxxxxxxxxxxxxx> 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@xxxxxxxxxxxxxxxxx> Signed-off-by: Guo Ren <guoren@xxxxxxxxxx> Cc: Arnd Bergmann <arnd@xxxxxxxx> Cc: Palmer Dabbelt <palmer@xxxxxxxxxxx> --- 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@xxxxxxxxxxxx>
