[PATCH v3 19/20] x86/kprobes: Use vmalloc special flag

From: Rick Edgecombe <rick.p.edgecombe@intel.com>
To: 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>,
	Borislav Petkov <bp@alien8.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,
	Rick Edgecombe <rick.p.edgecombe@intel.com>,
	Masami Hiramatsu <mhiramat@kernel.org>
Subject: [PATCH v3 19/20] x86/kprobes: Use vmalloc special flag
Date: Thu, 21 Feb 2019 15:44:50 -0800	[thread overview]
Message-ID: <20190221234451.17632-20-rick.p.edgecombe@intel.com> (raw)
In-Reply-To: <20190221234451.17632-1-rick.p.edgecombe@intel.com>

Use new flag VM_FLUSH_RESET_PERMS for handling freeing of special
permissioned memory in vmalloc and remove places where memory was set NX
and RW before freeing which is no longer needed.

Cc: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Rick Edgecombe <rick.p.edgecombe@intel.com>
---
 arch/x86/kernel/kprobes/core.c | 7 +------
 1 file changed, 1 insertion(+), 6 deletions(-)

diff --git a/arch/x86/kernel/kprobes/core.c b/arch/x86/kernel/kprobes/core.c
index 98c671e89889..8b56935d7b53 100644
--- a/arch/x86/kernel/kprobes/core.c
+++ b/arch/x86/kernel/kprobes/core.c
@@ -434,6 +434,7 @@ void *alloc_insn_page(void)
 	if (!page)
 		return NULL;
 
+	set_vm_flush_reset_perms(page);
 	/*
 	 * First make the page read-only, and only then make it executable to
 	 * prevent it from being W+X in between.
@@ -452,12 +453,6 @@ void *alloc_insn_page(void)
 /* Recover page to RW mode before releasing it */
 void free_insn_page(void *page)
 {
-	/*
-	 * First make the page non-executable, and only then make it writable to
-	 * prevent it from being W+X in between.
-	 */
-	set_memory_nx((unsigned long)page, 1);
-	set_memory_rw((unsigned long)page, 1);
 	module_memfree(page);
 }
 
-- 
2.17.1

