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Subject[PATCH 4.4 020/312] MIPS: math-emu: Fix BC1{EQ,NE}Z emulation
Date
From: Paul Burton <paul.burton@imgtec.com>

commit 93583e178ebfdd2fadf950eef1547f305cac12ca upstream.

The conditions for branching when emulating the BC1EQZ & BC1NEZ
instructions were backwards, leading to each of those instructions being
treated as the other. Fix this by reversing the conditions, and clear up
the code a little for readability & checkpatch.

Fixes: c909ca718e8f ("MIPS: math-emu: Emulate missing BC1{EQ,NE}Z instructions")
Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Reviewed-by: James Hogan <james.hogan@imgtec.com>
Cc: Maciej W. Rozycki <macro@imgtec.com>
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/13150/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
arch/mips/math-emu/cp1emu.c | 11 ++++++-----
1 file changed, 6 insertions(+), 5 deletions(-)

--- a/arch/mips/math-emu/cp1emu.c
+++ b/arch/mips/math-emu/cp1emu.c
@@ -975,9 +975,10 @@ static int cop1Emulate(struct pt_regs *x
struct mm_decoded_insn dec_insn, void *__user *fault_addr)
{
unsigned long contpc = xcp->cp0_epc + dec_insn.pc_inc;
- unsigned int cond, cbit;
+ unsigned int cond, cbit, bit0;
mips_instruction ir;
int likely, pc_inc;
+ union fpureg *fpr;
u32 __user *wva;
u64 __user *dva;
u32 wval;
@@ -1189,14 +1190,14 @@ emul:
return SIGILL;

cond = likely = 0;
+ fpr = &current->thread.fpu.fpr[MIPSInst_RT(ir)];
+ bit0 = get_fpr32(fpr, 0) & 0x1;
switch (MIPSInst_RS(ir)) {
case bc1eqz_op:
- if (get_fpr32(&current->thread.fpu.fpr[MIPSInst_RT(ir)], 0) & 0x1)
- cond = 1;
+ cond = bit0 == 0;
break;
case bc1nez_op:
- if (!(get_fpr32(&current->thread.fpu.fpr[MIPSInst_RT(ir)], 0) & 0x1))
- cond = 1;
+ cond = bit0 != 0;
break;
}
goto branch_common;

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