[PATCH v2 18/20] x86/ftrace: 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>,
	Steven Rostedt <rostedt@goodmis.org>
Subject: [PATCH v2 18/20] x86/ftrace: Use vmalloc special flag
Date: Mon, 28 Jan 2019 16:34:20 -0800	[thread overview]
Message-ID: <20190129003422.9328-19-rick.p.edgecombe@intel.com> (raw)
In-Reply-To: <20190129003422.9328-1-rick.p.edgecombe@intel.com>

Use new flag VM_HAS_SPECIAL_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: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Rick Edgecombe <rick.p.edgecombe@intel.com>
---
 arch/x86/kernel/ftrace.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/arch/x86/kernel/ftrace.c b/arch/x86/kernel/ftrace.c
index 13c8249b197f..cf30594a2032 100644
--- a/arch/x86/kernel/ftrace.c
+++ b/arch/x86/kernel/ftrace.c
@@ -692,10 +692,6 @@ static inline void *alloc_tramp(unsigned long size)
 }
 static inline void tramp_free(void *tramp, int size)
 {
-	int npages = PAGE_ALIGN(size) >> PAGE_SHIFT;
-
-	set_memory_nx((unsigned long)tramp, npages);
-	set_memory_rw((unsigned long)tramp, npages);
 	module_memfree(tramp);
 }
 #else
@@ -820,6 +816,8 @@ create_trampoline(struct ftrace_ops *ops, unsigned int *tramp_size)
 	/* ALLOC_TRAMP flags lets us know we created it */
 	ops->flags |= FTRACE_OPS_FL_ALLOC_TRAMP;
 
+	set_vm_special(trampoline);
+
 	/*
 	 * Module allocation needs to be completed by making the page
 	 * executable. The page is still writable, which is a security hazard,
-- 
2.17.1

