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>,
Peter Zijlstra <peterz@infradead.org>, <linux_dti@icloud.com>,
<linux-integrity@vger.kernel.org>,
<linux-security-module@vger.kernel.org>,
Nadav Amit <namit@vmware.com>
Subject: [PATCH v6 07/10] x86/kgdb: avoid redundant comparison of patched code
Date: Tue, 20 Nov 2018 12:35:42 -0800 [thread overview]
Message-ID: <20181120203545.34928-8-namit@vmware.com> (raw)
In-Reply-To: <20181120203545.34928-1-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 | 14 +-------------
1 file changed, 1 insertion(+), 13 deletions(-)
diff --git a/arch/x86/kernel/kgdb.c b/arch/x86/kernel/kgdb.c
index 2636ca8394bd..86484510bf54 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,
@@ -770,11 +769,6 @@ int kgdb_arch_set_breakpoint(struct kgdb_bkpt *bpt)
return -EBUSY;
text_poke_kgdb((void *)bpt->bpt_addr, arch_kgdb_ops.gdb_bpt_instr,
BREAK_INSTR_SIZE);
- 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;
@@ -782,9 +776,6 @@ 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;
/*
@@ -795,10 +786,7 @@ int kgdb_arch_remove_breakpoint(struct kgdb_bkpt *bpt)
goto knl_write;
text_poke_kgdb((void *)bpt->bpt_addr, bpt->saved_instr,
BREAK_INSTR_SIZE);
- 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;
+ return 0;
knl_write:
return probe_kernel_write((char *)bpt->bpt_addr,
--
2.17.1
next prev parent reply other threads:[~2018-11-21 3:53 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-20 20:35 [PATCH v6 00/10] x86/alternative: text_poke() fixes Nadav Amit
2018-11-20 20:35 ` [PATCH v6 01/10] Fix "x86/alternatives: Lockdep-enforce text_mutex in text_poke*()" Nadav Amit
2018-11-20 20:35 ` [PATCH v6 02/10] x86/jump_label: Use text_poke_early() during early init Nadav Amit
2018-11-20 20:35 ` [PATCH v6 03/10] x86/mm: temporary mm struct Nadav Amit
2018-11-20 20:35 ` [PATCH v6 04/10] fork: provide a function for copying init_mm Nadav Amit
2018-11-20 20:35 ` [PATCH v6 05/10] x86/alternative: initializing temporary mm for patching Nadav Amit
2018-11-20 20:35 ` [PATCH v6 06/10] x86/alternative: use temporary mm for text poking Nadav Amit
2018-11-20 20:35 ` Nadav Amit [this message]
2018-11-20 20:35 ` [PATCH v6 08/10] x86: avoid W^X being broken during modules loading Nadav Amit
2018-11-28 18:59 ` Nadav Amit
2018-11-30 2:32 ` Masami Hiramatsu
2018-11-20 20:35 ` [PATCH v6 09/10] x86/jump-label: remove support for custom poker Nadav Amit
2018-11-20 20:35 ` [PATCH v6 10/10] x86/alternative: remove the return value of text_poke_*() Nadav Amit
2018-11-26 10:32 ` [PATCH v6 00/10] x86/alternative: text_poke() fixes Peter Zijlstra
2018-11-26 17:46 ` Nadav Amit
2018-11-29 12:58 ` Peter Zijlstra
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