Unverified Commit ebcbd75e authored May 08, 2018 by Alan Kao Committed by Palmer Dabbelt Jun 04, 2018

riscv: Fix the bug in memory access fixup code



A piece of fixup code is currently shared by __copy_user and
__clear_user.  It first disables the access to user-space memory
and then returns the "n" argument, which represents #(bytes not processed).
However,__copy_user's "n" is in register a2, while __clear_user's in a1,
and thus it causes errors for programs like setdomainname02 testcase in LTP.

This patch fixes this issue by separating their fixup code and returning
the right value for the kernel to handle a relative fault properly.

Signed-off-by: Alan Kao <alankao@andestech.com>
Cc: Greentime Hu <greentime@andestech.com>
Cc: Zong Li <zong@andestech.com>
Cc: Vincent Chen <vincentc@andestech.com>
Signed-off-by: Palmer Dabbelt <palmer@sifive.com>

parent 29dcea88

arch/riscv/lib/uaccess.S

+9 −4

Original line number	Diff line number	Diff line
		@@ -84,7 +84,7 @@ ENTRY(__clear_user)
		bgeu t0, t1, 2f
		bltu a0, t0, 4f
		1:
		fixup REG_S, zero, (a0), 10f
		fixup REG_S, zero, (a0), 11f
		addi a0, a0, SZREG
		bltu a0, t1, 1b
		2:
		@@ -96,12 +96,12 @@ ENTRY(__clear_user)
		li a0, 0
		ret
		4: /* Edge case: unalignment */
		fixup sb, zero, (a0), 10f
		fixup sb, zero, (a0), 11f
		addi a0, a0, 1
		bltu a0, t0, 4b
		j 1b
		5: /* Edge case: remainder */
		fixup sb, zero, (a0), 10f
		fixup sb, zero, (a0), 11f
		addi a0, a0, 1
		bltu a0, a3, 5b
		j 3b
		@@ -109,9 +109,14 @@ ENDPROC(__clear_user)

		.section .fixup,"ax"
		.balign 4
		/* Fixup code for __copy_user(10) and __clear_user(11) */
		10:
		/* Disable access to user memory */
		csrs sstatus, t6
		sub a0, a3, a0
		mv a0, a2
		ret
		11:
		csrs sstatus, t6
		mv a0, a1
		ret
		.previous

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