Unverified Commit f81393a5 authored Jan 23, 2022 by Jisheng Zhang Committed by Palmer Dabbelt Feb 08, 2022

riscv: extable: fix err reg writing in dedicated uaccess handler



Mayuresh reported commit 20802d8d ("riscv: extable: add a dedicated
uaccess handler") breaks the writev02 test case in LTP. This is due to
the err reg isn't correctly set with the errno(-EFAULT in writev02
case). First of all, the err and zero regs are reg numbers rather than
reg offsets in struct pt_regs; Secondly, regs_set_gpr() should write
the regs when offset isn't zero(zero means epc)

Fix it by correcting regs_set_gpr() logic and passing the correct reg
offset to it.

Reported-by: Mayuresh Chitale <mchitale@ventanamicro.com>
Fixes: 20802d8d ("riscv: extable: add a dedicated uaccess handler")
Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
Cc: stable@vger.kernel.org
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>

parent ca0cb9a6

arch/riscv/mm/extable.c

+3 −3

Original line number	Diff line number	Diff line
		@@ -33,7 +33,7 @@ static inline void regs_set_gpr(struct pt_regs *regs, unsigned int offset,
		if (unlikely(offset > MAX_REG_OFFSET))
		return;

		if (!offset)
		if (offset)
		(unsigned long )((unsigned long)regs + offset) = val;
		}

		@@ -43,8 +43,8 @@ static bool ex_handler_uaccess_err_zero(const struct exception_table_entry *ex,
		int reg_err = FIELD_GET(EX_DATA_REG_ERR, ex->data);
		int reg_zero = FIELD_GET(EX_DATA_REG_ZERO, ex->data);

		regs_set_gpr(regs, reg_err, -EFAULT);
		regs_set_gpr(regs, reg_zero, 0);
		regs_set_gpr(regs, reg_err * sizeof(unsigned long), -EFAULT);
		regs_set_gpr(regs, reg_zero * sizeof(unsigned long), 0);

		regs->epc = get_ex_fixup(ex);
		return true;