diff options
Diffstat (limited to 'arch/riscv/lib/uaccess.S')
| -rw-r--r-- | arch/riscv/lib/uaccess.S | 117 |
1 files changed, 117 insertions, 0 deletions
diff --git a/arch/riscv/lib/uaccess.S b/arch/riscv/lib/uaccess.S new file mode 100644 index 000000000000..58fb2877c865 --- /dev/null +++ b/arch/riscv/lib/uaccess.S @@ -0,0 +1,117 @@ +#include <linux/linkage.h> +#include <asm/asm.h> +#include <asm/csr.h> + + .altmacro + .macro fixup op reg addr lbl + LOCAL _epc +_epc: + \op \reg, \addr + .section __ex_table,"a" + .balign RISCV_SZPTR + RISCV_PTR _epc, \lbl + .previous + .endm + +ENTRY(__copy_user) + + /* Enable access to user memory */ + li t6, SR_SUM + csrs sstatus, t6 + + add a3, a1, a2 + /* Use word-oriented copy only if low-order bits match */ + andi t0, a0, SZREG-1 + andi t1, a1, SZREG-1 + bne t0, t1, 2f + + addi t0, a1, SZREG-1 + andi t1, a3, ~(SZREG-1) + andi t0, t0, ~(SZREG-1) + /* + * a3: terminal address of source region + * t0: lowest XLEN-aligned address in source + * t1: highest XLEN-aligned address in source + */ + bgeu t0, t1, 2f + bltu a1, t0, 4f +1: + fixup REG_L, t2, (a1), 10f + fixup REG_S, t2, (a0), 10f + addi a1, a1, SZREG + addi a0, a0, SZREG + bltu a1, t1, 1b +2: + bltu a1, a3, 5f + +3: + /* Disable access to user memory */ + csrc sstatus, t6 + li a0, 0 + ret +4: /* Edge case: unalignment */ + fixup lbu, t2, (a1), 10f + fixup sb, t2, (a0), 10f + addi a1, a1, 1 + addi a0, a0, 1 + bltu a1, t0, 4b + j 1b +5: /* Edge case: remainder */ + fixup lbu, t2, (a1), 10f + fixup sb, t2, (a0), 10f + addi a1, a1, 1 + addi a0, a0, 1 + bltu a1, a3, 5b + j 3b +ENDPROC(__copy_user) + + +ENTRY(__clear_user) + + /* Enable access to user memory */ + li t6, SR_SUM + csrs sstatus, t6 + + add a3, a0, a1 + addi t0, a0, SZREG-1 + andi t1, a3, ~(SZREG-1) + andi t0, t0, ~(SZREG-1) + /* + * a3: terminal address of target region + * t0: lowest doubleword-aligned address in target region + * t1: highest doubleword-aligned address in target region + */ + bgeu t0, t1, 2f + bltu a0, t0, 4f +1: + fixup REG_S, zero, (a0), 10f + addi a0, a0, SZREG + bltu a0, t1, 1b +2: + bltu a0, a3, 5f + +3: + /* Disable access to user memory */ + csrc sstatus, t6 + li a0, 0 + ret +4: /* Edge case: unalignment */ + fixup sb, zero, (a0), 10f + addi a0, a0, 1 + bltu a0, t0, 4b + j 1b +5: /* Edge case: remainder */ + fixup sb, zero, (a0), 10f + addi a0, a0, 1 + bltu a0, a3, 5b + j 3b +ENDPROC(__clear_user) + + .section .fixup,"ax" + .balign 4 +10: + /* Disable access to user memory */ + csrs sstatus, t6 + sub a0, a3, a0 + ret + .previous |