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From: Jiaxun Yang <jiaxun.yang@flygoat.com>
Date: Fri, 02 Feb 2024 12:30:27 +0000
Subject: [PATCH v2 2/3] MIPS: Clear Cause.BD in instruction_pointer_set
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Message-Id: <20240202-exception_ip-v2-2-e6894d5ce705@flygoat.com>
References: <20240202-exception_ip-v2-0-e6894d5ce705@flygoat.com>
In-Reply-To: <20240202-exception_ip-v2-0-e6894d5ce705@flygoat.com>
To: Oleg Nesterov <oleg@redhat.com>, 
 Thomas Bogendoerfer <tsbogend@alpha.franken.de>, 
 Andrew Morton <akpm@linux-foundation.org>, 
 Ben Hutchings <ben@decadent.org.uk>
Cc: linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org, 
 linux-mips@vger.kernel.org, linux-mm@kvack.org, 
 Jiaxun Yang <jiaxun.yang@flygoat.com>

Clear Cause.BD after we use instruction_pointer_set to override
EPC.

This can prevent exception_epc check against instruction code at
new return address.
It won't be considered as "in delay slot" after epc being overridden
anyway.

Signed-off-by: Jiaxun Yang <jiaxun.yang@flygoat.com>
---
 arch/mips/include/asm/ptrace.h | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/mips/include/asm/ptrace.h b/arch/mips/include/asm/ptrace.h
index 701a233583c2..d14d0e37ad02 100644
--- a/arch/mips/include/asm/ptrace.h
+++ b/arch/mips/include/asm/ptrace.h
@@ -60,6 +60,7 @@ static inline void instruction_pointer_set(struct pt_regs *regs,
                                            unsigned long val)
 {
 	regs->cp0_epc = val;
+	regs->cp0_cause &= ~CAUSEF_BD;
 }
 
 /* Query offset/name of register from its name/offset */

-- 
2.43.0