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 v5 07/10] x86/kgdb: avoid redundant comparison of patched code
Date: Tue, 13 Nov 2018 05:07:27 -0800 [thread overview]
Message-ID: <20181113130730.44844-8-namit@vmware.com> (raw)
In-Reply-To: <20181113130730.44844-1-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
next prev parent reply other threads:[~2018-11-13 20:26 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-13 13:07 [PATCH v5 00/10] x86/alternative: text_poke() fixes Nadav Amit
2018-11-13 13:07 ` [PATCH v5 01/10] Fix "x86/alternatives: Lockdep-enforce text_mutex in text_poke*()" Nadav Amit
2018-11-13 13:07 ` [PATCH v5 02/10] x86/jump_label: Use text_poke_early() during early init Nadav Amit
2018-11-20 18:10 ` H. Peter Anvin
2018-11-20 18:18 ` Peter Zijlstra
2018-11-20 18:23 ` H. Peter Anvin
2018-11-20 18:47 ` Nadav Amit
2018-11-13 13:07 ` [PATCH v5 03/10] x86/mm: temporary mm struct Nadav Amit
2018-11-13 13:07 ` [PATCH v5 04/10] fork: provide a function for copying init_mm Nadav Amit
2018-11-13 13:07 ` [PATCH v5 05/10] x86/alternative: initializing temporary mm for patching Nadav Amit
2018-11-13 13:07 ` [PATCH v5 06/10] x86/alternative: use temporary mm for text poking Nadav Amit
2018-11-13 13:07 ` Nadav Amit [this message]
2018-11-13 13:07 ` [PATCH v5 08/10] x86: avoid W^X being broken during modules loading Nadav Amit
2018-11-13 13:07 ` [PATCH v5 09/10] x86/jump-label: remove support for custom poker Nadav Amit
2018-11-13 13:07 ` [PATCH v5 10/10] x86/alternative: remove the return value of text_poke_*() Nadav Amit
2018-11-20 12:42 ` [PATCH v5 00/10] x86/alternative: text_poke() fixes Peter Zijlstra
2018-11-20 18:52 ` Nadav Amit
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20181113130730.44844-8-namit@vmware.com \
--to=namit@vmware.com \
--cc=bp@alien8.de \
--cc=dave.hansen@linux.intel.com \
--cc=hpa@zytor.com \
--cc=linux-integrity@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-security-module@vger.kernel.org \
--cc=linux_dti@icloud.com \
--cc=mingo@redhat.com \
--cc=peterz@infradead.org \
--cc=tglx@linutronix.de \
--cc=x86@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).