linux-kernel - [PATCH v3 18/20] x86/ftrace: Use vmalloc special flag

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Date:   Thu, 21 Feb 2019 15:44:49 -0800
From:   Rick Edgecombe <rick.p.edgecombe@...el.com>
To:     Andy Lutomirski <luto@...nel.org>, Ingo Molnar <mingo@...hat.com>
Cc:     linux-kernel@...r.kernel.org, x86@...nel.org, hpa@...or.com,
        Thomas Gleixner <tglx@...utronix.de>,
        Borislav Petkov <bp@...en8.de>,
        Nadav Amit <nadav.amit@...il.com>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Peter Zijlstra <peterz@...radead.org>, linux_dti@...oud.com,
        linux-integrity@...r.kernel.org,
        linux-security-module@...r.kernel.org, akpm@...ux-foundation.org,
        kernel-hardening@...ts.openwall.com, linux-mm@...ck.org,
        will.deacon@....com, ard.biesheuvel@...aro.org,
        kristen@...ux.intel.com, deneen.t.dock@...el.com,
        Rick Edgecombe <rick.p.edgecombe@...el.com>,
        Steven Rostedt <rostedt@...dmis.org>
Subject: [PATCH v3 18/20] x86/ftrace: Use vmalloc special flag

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: Steven Rostedt <rostedt@...dmis.org>
Acked-by: Steven Rostedt (VMware) <rostedt@...dmis.org>
Signed-off-by: Rick Edgecombe <rick.p.edgecombe@...el.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..93efe3955333 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_flush_reset_perms(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