From: Rick Edgecombe <rick.p.edgecombe@intel.com>
To: Borislav Petkov <bp@alien8.de>, Andy Lutomirski <luto@kernel.org>,
Ingo Molnar <mingo@redhat.com>
Cc: linux-kernel@vger.kernel.org, x86@kernel.org, hpa@zytor.com,
Thomas Gleixner <tglx@linutronix.de>,
Nadav Amit <nadav.amit@gmail.com>,
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, akpm@linux-foundation.org,
kernel-hardening@lists.openwall.com, linux-mm@kvack.org,
will.deacon@arm.com, ard.biesheuvel@linaro.org,
kristen@linux.intel.com, deneen.t.dock@intel.com,
Nadav Amit <namit@vmware.com>,
Rick Edgecombe <rick.p.edgecombe@intel.com>
Subject: [PATCH v4 08/23] x86/kgdb: Avoid redundant comparison of patched code
Date: Mon, 22 Apr 2019 11:57:50 -0700 [thread overview]
Message-ID: <20190422185805.1169-9-rick.p.edgecombe@intel.com> (raw)
In-Reply-To: <20190422185805.1169-1-rick.p.edgecombe@intel.com>
From: Nadav Amit <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.
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Nadav Amit <namit@vmware.com>
Signed-off-by: Rick Edgecombe <rick.p.edgecombe@intel.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 2b203ee5b879..13b13311b792 100644
--- a/arch/x86/kernel/kgdb.c
+++ b/arch/x86/kernel/kgdb.c
@@ -747,7 +747,6 @@ 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,
@@ -766,11 +765,6 @@ 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;
@@ -778,9 +772,6 @@ 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;
/*
@@ -791,10 +782,7 @@ 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:[~2019-04-22 19:00 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-04-22 18:57 [PATCH v4 00/23] Merge text_poke fixes and executable lockdowns Rick Edgecombe
2019-04-22 18:57 ` [PATCH v4 01/23] Fix "x86/alternatives: Lockdep-enforce text_mutex in text_poke*()" Rick Edgecombe
2019-04-22 18:57 ` [PATCH v4 02/23] x86/jump_label: Use text_poke_early() during early init Rick Edgecombe
2019-04-22 18:57 ` [PATCH v4 03/23] x86/mm: Introduce temporary mm structs Rick Edgecombe
2019-04-25 16:26 ` Borislav Petkov
2019-04-25 17:37 ` Nadav Amit
2019-04-25 17:49 ` Andy Lutomirski
2019-04-22 18:57 ` [PATCH v4 04/23] x86/mm: Save DRs when loading a temporary mm Rick Edgecombe
2019-04-25 16:36 ` Borislav Petkov
2019-04-25 18:17 ` Peter Zijlstra
2019-04-22 18:57 ` [PATCH v4 05/23] fork: Provide a function for copying init_mm Rick Edgecombe
2019-04-22 18:57 ` [PATCH v4 06/23] x86/alternative: Initialize temporary mm for patching Rick Edgecombe
2019-04-22 18:57 ` [PATCH v4 07/23] x86/alternative: Use temporary mm for text poking Rick Edgecombe
2019-04-22 18:57 ` Rick Edgecombe [this message]
2019-04-22 18:57 ` [PATCH v4 09/23] x86/ftrace: Set trampoline pages as executable Rick Edgecombe
2019-04-22 18:57 ` [PATCH v4 10/23] x86/kprobes: Set instruction page " Rick Edgecombe
2019-04-22 18:57 ` [PATCH v4 11/23] x86/module: Avoid breaking W^X while loading modules Rick Edgecombe
2019-04-22 18:57 ` [PATCH v4 12/23] x86/jump-label: Remove support for custom poker Rick Edgecombe
2019-04-22 18:57 ` [PATCH v4 13/23] x86/alternative: Remove the return value of text_poke_*() Rick Edgecombe
2019-04-22 18:57 ` [PATCH v4 14/23] x86/mm/cpa: Add set_direct_map_ functions Rick Edgecombe
2019-04-22 18:57 ` [PATCH v4 15/23] mm: Make hibernate handle unmapped pages Rick Edgecombe
2019-04-22 18:57 ` [PATCH v4 16/23] vmalloc: Add flag for free of special permsissions Rick Edgecombe
2019-04-25 20:38 ` Peter Zijlstra
2019-04-25 21:22 ` Edgecombe, Rick P
2019-04-22 18:57 ` [PATCH v4 17/23] modules: Use vmalloc special flag Rick Edgecombe
2019-04-22 18:58 ` [PATCH v4 18/23] bpf: " Rick Edgecombe
2019-04-22 18:58 ` [PATCH v4 19/23] x86/ftrace: " Rick Edgecombe
2019-04-25 18:28 ` Steven Rostedt
2019-04-25 19:19 ` Edgecombe, Rick P
2019-04-22 18:58 ` [PATCH v4 20/23] x86/kprobes: " Rick Edgecombe
2019-04-22 18:58 ` [PATCH v4 21/23] x86/alternative: Comment about module removal races Rick Edgecombe
2019-04-22 18:58 ` [PATCH v4 22/23] tlb: provide default nmi_uaccess_okay() Rick Edgecombe
2019-04-22 18:58 ` [PATCH v4 23/23] bpf: Fail bpf_probe_write_user() while mm is switched Rick Edgecombe
2019-04-25 20:48 ` [PATCH v4 00/23] Merge text_poke fixes and executable lockdowns Peter Zijlstra
2019-04-25 20:49 ` Peter Zijlstra
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