Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
From:   Nadav Amit <namit@vmware.com>
To:     Ingo Molnar <mingo@redhat.com>
CC:     <linux-kernel@vger.kernel.org>, <x86@kernel.org>,
        "H. Peter Anvin" <hpa@zytor.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Borislav Petkov <bp@alien8.de>,
        Dave Hansen <dave.hansen@linux.intel.com>,
        Nadav Amit <namit@vmware.com>
Subject: [PATCH v4 07/10] x86/kgdb: avoid redundant comparison of code
Date:   Sat, 10 Nov 2018 15:17:29 -0800
Message-ID: <20181110231732.15060-8-namit@vmware.com>
In-Reply-To: <20181110231732.15060-1-namit@vmware.com>
References: <20181110231732.15060-1-namit@vmware.com>
MIME-Version: 1.0
Content-Type: text/plain
Received-SPF: None (EX13-EDG-OU-001.vmware.com: namit@vmware.com does not
 designate permitted sender hosts)
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

text_poke() already ensures that the written value is the correct one
and fails if that is not the case. There is no need for an additional
comparison. Remove it.

Signed-off-by: Nadav Amit <namit@vmware.com>
---
 arch/x86/kernel/kgdb.c | 10 ----------
 1 file changed, 10 deletions(-)

diff --git a/arch/x86/kernel/kgdb.c b/arch/x86/kernel/kgdb.c
index 8091b2e381d4..d14e1be576fd 100644
--- a/arch/x86/kernel/kgdb.c
+++ b/arch/x86/kernel/kgdb.c
@@ -751,7 +751,6 @@ void kgdb_arch_set_pc(struct pt_regs *regs, unsigned long ip)
 int kgdb_arch_set_breakpoint(struct kgdb_bkpt *bpt)
 {
 	int err;
-	char opc[BREAK_INSTR_SIZE];
 
 	bpt->type = BP_BREAKPOINT;
 	err = probe_kernel_read(bpt->saved_instr, (char *)bpt->bpt_addr,
@@ -772,11 +771,6 @@ int kgdb_arch_set_breakpoint(struct kgdb_bkpt *bpt)
 			     BREAK_INSTR_SIZE);
 	if (err)
 		return err;
-	err = probe_kernel_read(opc, (char *)bpt->bpt_addr, BREAK_INSTR_SIZE);
-	if (err)
-		return err;
-	if (memcmp(opc, arch_kgdb_ops.gdb_bpt_instr, BREAK_INSTR_SIZE))
-		return -EINVAL;
 	bpt->type = BP_POKE_BREAKPOINT;
 
 	return err;
@@ -785,7 +779,6 @@ int kgdb_arch_set_breakpoint(struct kgdb_bkpt *bpt)
 int kgdb_arch_remove_breakpoint(struct kgdb_bkpt *bpt)
 {
 	int err;
-	char opc[BREAK_INSTR_SIZE];
 
 	if (bpt->type != BP_POKE_BREAKPOINT)
 		goto knl_write;
@@ -798,9 +791,6 @@ int kgdb_arch_remove_breakpoint(struct kgdb_bkpt *bpt)
 	err = text_poke_kgdb((void *)bpt->bpt_addr, bpt->saved_instr,
 			     BREAK_INSTR_SIZE);
 	if (err)
-		return err;
-	err = probe_kernel_read(opc, (char *)bpt->bpt_addr, BREAK_INSTR_SIZE);
-	if (err || memcmp(opc, bpt->saved_instr, BREAK_INSTR_SIZE))
 		goto knl_write;
 	return err;
 
-- 
2.17.1