linux-kernel - [PATCH RFC 2/8] powerpc: Use barrier_nospec in copy_from

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Message-Id: <38f5e330801b677df65c774b214b79b799975be4.1520965380.git.msuchanek@suse.de>
Date:   Tue, 13 Mar 2018 19:33:00 +0100
From:   Michal Suchanek <msuchanek@...e.de>
To:     linuxppc-dev@...ts.ozlabs.org
Cc:     Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Michael Ellerman <mpe@...erman.id.au>,
        Peter Zijlstra <peterz@...radead.org>,
        Michal Suchanek <msuchanek@...e.de>,
        Kate Stewart <kstewart@...uxfoundation.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Philippe Ombredanne <pombredanne@...b.com>,
        Nicholas Piggin <npiggin@...il.com>,
        "Tobin C. Harding" <me@...in.cc>,
        Mahesh Salgaonkar <mahesh@...ux.vnet.ibm.com>,
        David Gibson <david@...son.dropbear.id.au>,
        Al Viro <viro@...iv.linux.org.uk>,
        Michael Neuling <mikey@...ling.org>,
        "Oliver O'Halloran" <oohall@...il.com>,
        "Naveen N. Rao" <naveen.n.rao@...ux.vnet.ibm.com>,
        Madhavan Srinivasan <maddy@...ux.vnet.ibm.com>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Balbir Singh <bsingharora@...il.com>,
        Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
        Christophe Leroy <christophe.leroy@....fr>,
        Andrew Donnellan <andrew.donnellan@....ibm.com>,
        Daniel Axtens <dja@...ens.net>,
        Russell Currey <ruscur@...sell.cc>,
        Joe Perches <joe@...ches.com>,
        "Bryant G. Ly" <bryantly@...ux.vnet.ibm.com>,
        Cédric Le Goater <clg@...d.org>,
        linux-kernel@...r.kernel.org
Subject: [PATCH RFC 2/8] powerpc: Use barrier_nospec in copy_from_user

Coopypasta from x86.

Signed-off-by: Michal Suchanek <msuchanek@...e.de>
---
 arch/powerpc/include/asm/uaccess.h | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/include/asm/uaccess.h b/arch/powerpc/include/asm/uaccess.h
index 51bfeb8777f0..af9b0e731f46 100644
--- a/arch/powerpc/include/asm/uaccess.h
+++ b/arch/powerpc/include/asm/uaccess.h
@@ -248,6 +248,7 @@ do {								\
 	__chk_user_ptr(ptr);					\
 	if (!is_kernel_addr((unsigned long)__gu_addr))		\
 		might_fault();					\
+	barrier_nospec();					\
 	__get_user_size(__gu_val, __gu_addr, (size), __gu_err);	\
 	(x) = (__typeof__(*(ptr)))__gu_val;			\
 	__gu_err;						\
@@ -258,8 +259,10 @@ do {								\
 	long __gu_err = -EFAULT;					\
 	unsigned long  __gu_val = 0;					\
 	const __typeof__(*(ptr)) __user *__gu_addr = (ptr);		\
+	int can_access = access_ok(VERIFY_READ, __gu_addr, (size));	\
 	might_fault();							\
-	if (access_ok(VERIFY_READ, __gu_addr, (size)))			\
+	barrier_nospec();						\
+	if (can_access)							\
 		__get_user_size(__gu_val, __gu_addr, (size), __gu_err);	\
 	(x) = (__force __typeof__(*(ptr)))__gu_val;				\
 	__gu_err;							\
@@ -271,6 +274,7 @@ do {								\
 	unsigned long __gu_val;					\
 	const __typeof__(*(ptr)) __user *__gu_addr = (ptr);	\
 	__chk_user_ptr(ptr);					\
+	barrier_nospec();					\
 	__get_user_size(__gu_val, __gu_addr, (size), __gu_err);	\
 	(x) = (__force __typeof__(*(ptr)))__gu_val;			\
 	__gu_err;						\
@@ -298,15 +302,19 @@ static inline unsigned long raw_copy_from_user(void *to,
 
 		switch (n) {
 		case 1:
+			barrier_nospec();
 			__get_user_size(*(u8 *)to, from, 1, ret);
 			break;
 		case 2:
+			barrier_nospec();
 			__get_user_size(*(u16 *)to, from, 2, ret);
 			break;
 		case 4:
+			barrier_nospec();
 			__get_user_size(*(u32 *)to, from, 4, ret);
 			break;
 		case 8:
+			barrier_nospec();
 			__get_user_size(*(u64 *)to, from, 8, ret);
 			break;
 		}
@@ -314,6 +322,7 @@ static inline unsigned long raw_copy_from_user(void *to,
 			return 0;
 	}
 
+	barrier_nospec();
 	return __copy_tofrom_user((__force void __user *)to, from, n);
 }
 
-- 
2.13.6