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csky: Fixup regs.sr broken in ptrace

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commit af89ebaa64de726ca0a39bbb0bf0c81a1f43ad50 upstream.

gpr_get() return the entire pt_regs (include sr) to userspace, if we
don't restore the C bit in gpr_set, it may break the ALU result in
that context. So the C flag bit is part of gpr context, that's why
riscv totally remove the C bit in the ISA. That makes sr reg clear
from userspace to supervisor privilege.

Signed-off-by: Guo Ren <guoren@linux.alibaba.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: stable@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Guo Ren 2021-09-24 15:33:38 +08:00 committed by Greg Kroah-Hartman
parent 5dab6e8f14
commit 0c97008859
1 changed files with 2 additions and 1 deletions
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3
arch/csky/kernel/ptrace.c
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@ -98,7 +98,8 @@ static int gpr_set(struct task_struct *target,
if (ret)
return ret;
regs.sr = task_pt_regs(target)->sr;
/* BIT(0) of regs.sr is Condition Code/Carry bit */
regs.sr = (regs.sr & BIT(0)) | (task_pt_regs(target)->sr & ~BIT(0));
#ifdef CONFIG_CPU_HAS_HILO
regs.dcsr = task_pt_regs(target)->dcsr;
#endif