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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	[thread overview]
Message-ID: <20181110231732.15060-8-namit@vmware.com> (raw)
In-Reply-To: <20181110231732.15060-1-namit@vmware.com>

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


  parent reply	other threads:[~2018-11-11  6:35 UTC|newest]

Thread overview: 29+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-11-10 23:17 [PATCH v4 00/10] x86/alternative: text_poke() fixes Nadav Amit
2018-11-10 23:17 ` [PATCH v4 01/10] Fix "x86/alternatives: Lockdep-enforce text_mutex in text_poke*()" Nadav Amit
2018-11-12  2:54   ` Masami Hiramatsu
2018-11-12 10:59     ` Jiri Kosina
2018-11-10 23:17 ` [PATCH v4 02/10] x86/jump_label: Use text_poke_early() during early init Nadav Amit
2018-11-12 20:12   ` Nadav Amit
2018-11-10 23:17 ` [PATCH v4 03/10] x86/mm: temporary mm struct Nadav Amit
2018-11-10 23:17 ` [PATCH v4 04/10] fork: provide a function for copying init_mm Nadav Amit
2018-11-10 23:17 ` [PATCH v4 05/10] x86/alternative: initializing temporary mm for patching Nadav Amit
2018-11-11 14:43   ` Peter Zijlstra
2018-11-11 20:38     ` Nadav Amit
2018-11-12  0:34       ` Peter Zijlstra
2018-11-10 23:17 ` [PATCH v4 06/10] x86/alternative: use temporary mm for text poking Nadav Amit
2018-11-11 14:59   ` Peter Zijlstra
2018-11-11 20:53     ` Nadav Amit
2018-11-11 23:52       ` Peter Zijlstra
2018-11-12  0:09         ` Nadav Amit
2018-11-12  0:41           ` Peter Zijlstra
2018-11-12  0:36         ` Peter Zijlstra
2018-11-12  3:46         ` Ingo Molnar
2018-11-12  8:50           ` Peter Zijlstra
2018-11-11 19:11   ` Damian Tometzki
2018-11-11 20:41     ` Nadav Amit
2018-11-10 23:17 ` Nadav Amit [this message]
2018-11-10 23:17 ` [PATCH v4 08/10] x86: avoid W^X being broken during modules loading Nadav Amit
2018-11-10 23:17 ` [PATCH v4 09/10] x86/jump-label: remove support for custom poker Nadav Amit
2018-11-11 15:05   ` Peter Zijlstra
2018-11-11 20:31     ` Nadav Amit
2018-11-10 23:17 ` [PATCH v4 10/10] x86/alternative: remove the return value of text_poke_*() Nadav Amit

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