[RFC][PATCH v2 1/8] futex: arch_futex_atomic_op_inuser() calling conventions change

[RFC][PATCH v2 1/8] futex: arch_futex_atomic_op_inuser() calling conventions change

[Al Viro]

From: Al Viro <viro@zeniv.linux.org.uk>

Move access_ok() in and pagefault_enable()/pagefault_disable() out.
Mechanical conversion only - some instances don't really need
a separate access_ok() at all (e.g. the ones only using
get_user()/put_user(), or architectures where access_ok()
is always true); we'll deal with that in followups.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
 arch/alpha/include/asm/futex.h      | 5 ++---
 arch/arc/include/asm/futex.h        | 5 +++--
 arch/arm/include/asm/futex.h        | 5 +++--
 arch/arm64/include/asm/futex.h      | 5 ++---
 arch/hexagon/include/asm/futex.h    | 5 ++---
 arch/ia64/include/asm/futex.h       | 5 ++---
 arch/microblaze/include/asm/futex.h | 5 ++---
 arch/mips/include/asm/futex.h       | 5 ++---
 arch/nds32/include/asm/futex.h      | 6 ++----
 arch/openrisc/include/asm/futex.h   | 5 ++---
 arch/parisc/include/asm/futex.h     | 5 +++--
 arch/powerpc/include/asm/futex.h    | 5 ++---
 arch/riscv/include/asm/futex.h      | 5 ++---
 arch/s390/include/asm/futex.h       | 4 ++--
 arch/sh/include/asm/futex.h         | 5 ++---
 arch/sparc/include/asm/futex_64.h   | 6 ++----
 arch/x86/include/asm/futex.h        | 5 ++---
 arch/xtensa/include/asm/futex.h     | 5 ++---
 include/asm-generic/futex.h         | 4 ++--
 kernel/futex.c                      | 5 ++---
 20 files changed, 43 insertions(+), 57 deletions(-)

diff --git a/arch/alpha/include/asm/futex.h b/arch/alpha/include/asm/futex.h
index bfd3c01038f8..da67afd578fd 100644
--- a/arch/alpha/include/asm/futex.h
+++ b/arch/alpha/include/asm/futex.h
@@ -31,7 +31,8 @@ static inline int arch_futex_atomic_op_inuser(int op, int oparg, int *oval,
 {
 	int oldval = 0, ret;
 
-	pagefault_disable();
+	if (!access_ok(uaddr, sizeof(u32)))
+		return -EFAULT;
 
 	switch (op) {
 	case FUTEX_OP_SET:
@@ -53,8 +54,6 @@ static inline int arch_futex_atomic_op_inuser(int op, int oparg, int *oval,
 		ret = -ENOSYS;
 	}
 
-	pagefault_enable();
-
 	if (!ret)
 		*oval = oldval;
 
diff --git a/arch/arc/include/asm/futex.h b/arch/arc/include/asm/futex.h
index 9d0d070e6c22..607d1c16d4dd 100644
--- a/arch/arc/include/asm/futex.h
+++ b/arch/arc/include/asm/futex.h
@@ -75,10 +75,12 @@ static inline int arch_futex_atomic_op_inuser(int op, int oparg, int *oval,
 {
 	int oldval = 0, ret;
 
+	if (!access_ok(uaddr, sizeof(u32)))
+		return -EFAULT;
+
 #ifndef CONFIG_ARC_HAS_LLSC
 	preempt_disable();	/* to guarantee atomic r-m-w of futex op */
 #endif
-	pagefault_disable();
 
 	switch (op) {
 	case FUTEX_OP_SET:
@@ -101,7 +103,6 @@ static inline int arch_futex_atomic_op_inuser(int op, int oparg, int *oval,
 		ret = -ENOSYS;
 	}
 
-	pagefault_enable();
 #ifndef CONFIG_ARC_HAS_LLSC
 	preempt_enable();
 #endif
diff --git a/arch/arm/include/asm/futex.h b/arch/arm/include/asm/futex.h
index 83c391b597d4..e133da303a98 100644
--- a/arch/arm/include/asm/futex.h
+++ b/arch/arm/include/asm/futex.h
@@ -134,10 +134,12 @@ arch_futex_atomic_op_inuser(int op, int oparg, int *oval, u32 __user *uaddr)
 {
 	int oldval = 0, ret, tmp;
 
+	if (!access_ok(uaddr, sizeof(u32)))
+		return -EFAULT;
+
 #ifndef CONFIG_SMP
 	preempt_disable();
 #endif
-	pagefault_disable();
 
 	switch (op) {
 	case FUTEX_OP_SET:
@@ -159,7 +161,6 @@ arch_futex_atomic_op_inuser(int op, int oparg, int *oval, u32 __user *uaddr)
 		ret = -ENOSYS;
 	}
 
-	pagefault_enable();
 #ifndef CONFIG_SMP
 	preempt_enable();
 #endif
diff --git a/arch/arm64/include/asm/futex.h b/arch/arm64/include/asm/futex.h
index 6cc26a127819..97f6a63810ec 100644
--- a/arch/arm64/include/asm/futex.h
+++ b/arch/arm64/include/asm/futex.h
@@ -48,7 +48,8 @@ arch_futex_atomic_op_inuser(int op, int oparg, int *oval, u32 __user *_uaddr)
 	int oldval = 0, ret, tmp;
 	u32 __user *uaddr = __uaccess_mask_ptr(_uaddr);
 
-	pagefault_disable();
+	if (!access_ok(_uaddr, sizeof(u32)))
+		return -EFAULT;
 
 	switch (op) {
 	case FUTEX_OP_SET:
@@ -75,8 +76,6 @@ arch_futex_atomic_op_inuser(int op, int oparg, int *oval, u32 __user *_uaddr)
 		ret = -ENOSYS;
 	}
 
-	pagefault_enable();
-
 	if (!ret)
 		*oval = oldval;
 
diff --git a/arch/hexagon/include/asm/futex.h b/arch/hexagon/include/asm/futex.h
index 0191f7c7193e..6b9c554aee78 100644
--- a/arch/hexagon/include/asm/futex.h
+++ b/arch/hexagon/include/asm/futex.h
@@ -36,7 +36,8 @@ arch_futex_atomic_op_inuser(int op, int oparg, int *oval, u32 __user *uaddr)
 {
 	int oldval = 0, ret;
 
-	pagefault_disable();
+	if (!access_ok(uaddr, sizeof(u32)))
+		return -EFAULT;
 
 	switch (op) {
 	case FUTEX_OP_SET:
@@ -62,8 +63,6 @@ arch_futex_atomic_op_inuser(int op, int oparg, int *oval, u32 __user *uaddr)
 		ret = -ENOSYS;
 	}
 
-	pagefault_enable();
-
 	if (!ret)
 		*oval = oldval;
 
diff --git a/arch/ia64/include/asm/futex.h b/arch/ia64/include/asm/futex.h
index 2e106d462196..1db26b432d8c 100644
--- a/arch/ia64/include/asm/futex.h
+++ b/arch/ia64/include/asm/futex.h
@@ -50,7 +50,8 @@ arch_futex_atomic_op_inuser(int op, int oparg, int *oval, u32 __user *uaddr)
 {
 	int oldval = 0, ret;
 
-	pagefault_disable();
+	if (!access_ok(uaddr, sizeof(u32)))
+		return -EFAULT;
 
 	switch (op) {
 	case FUTEX_OP_SET:
@@ -74,8 +75,6 @@ arch_futex_atomic_op_inuser(int op, int oparg, int *oval, u32 __user *uaddr)
 		ret = -ENOSYS;
 	}
 
-	pagefault_enable();
-
 	if (!ret)
 		*oval = oldval;
 
diff --git a/arch/microblaze/include/asm/futex.h b/arch/microblaze/include/asm/futex.h
index 8c90357e5983..86131ed84c9a 100644
--- a/arch/microblaze/include/asm/futex.h
+++ b/arch/microblaze/include/asm/futex.h
@@ -34,7 +34,8 @@ arch_futex_atomic_op_inuser(int op, int oparg, int *oval, u32 __user *uaddr)
 {
 	int oldval = 0, ret;
 
-	pagefault_disable();
+	if (!access_ok(uaddr, sizeof(u32)))
+		return -EFAULT;
 
 	switch (op) {
 	case FUTEX_OP_SET:
@@ -56,8 +57,6 @@ arch_futex_atomic_op_inuser(int op, int oparg, int *oval, u32 __user *uaddr)
 		ret = -ENOSYS;
 	}
 
-	pagefault_enable();
-
 	if (!ret)
 		*oval = oldval;
 
diff --git a/arch/mips/include/asm/futex.h b/arch/mips/include/asm/futex.h
index 110220705e97..2bf8f6014579 100644
--- a/arch/mips/include/asm/futex.h
+++ b/arch/mips/include/asm/futex.h
@@ -89,7 +89,8 @@ arch_futex_atomic_op_inuser(int op, int oparg, int *oval, u32 __user *uaddr)
 {
 	int oldval = 0, ret;
 
-	pagefault_disable();
+	if (!access_ok(uaddr, sizeof(u32)))
+		return -EFAULT;
 
 	switch (op) {
 	case FUTEX_OP_SET:
@@ -116,8 +117,6 @@ arch_futex_atomic_op_inuser(int op, int oparg, int *oval, u32 __user *uaddr)
 		ret = -ENOSYS;
 	}
 
-	pagefault_enable();
-
 	if (!ret)
 		*oval = oldval;
 
diff --git a/arch/nds32/include/asm/futex.h b/arch/nds32/include/asm/futex.h
index 5213c65c2e0b..4223f473bd36 100644
--- a/arch/nds32/include/asm/futex.h
+++ b/arch/nds32/include/asm/futex.h
@@ -66,8 +66,8 @@ arch_futex_atomic_op_inuser(int op, int oparg, int *oval, u32 __user *uaddr)
 {
 	int oldval = 0, ret;
 
-
-	pagefault_disable();
+	if (!access_ok(uaddr, sizeof(u32)))
+		return -EFAULT;
 	switch (op) {
 	case FUTEX_OP_SET:
 		__futex_atomic_op("move	%0, %3", ret, oldval, tmp, uaddr,
@@ -93,8 +93,6 @@ arch_futex_atomic_op_inuser(int op, int oparg, int *oval, u32 __user *uaddr)
 		ret = -ENOSYS;
 	}
 
-	pagefault_enable();
-
 	if (!ret)
 		*oval = oldval;
 
diff --git a/arch/openrisc/include/asm/futex.h b/arch/openrisc/include/asm/futex.h
index fe894e6331ae..865e9cd0d97b 100644
--- a/arch/openrisc/include/asm/futex.h
+++ b/arch/openrisc/include/asm/futex.h
@@ -35,7 +35,8 @@ arch_futex_atomic_op_inuser(int op, int oparg, int *oval, u32 __user *uaddr)
 {
 	int oldval = 0, ret;
 
-	pagefault_disable();
+	if (!access_ok(uaddr, sizeof(u32)))
+		return -EFAULT;
 
 	switch (op) {
 	case FUTEX_OP_SET:
@@ -57,8 +58,6 @@ arch_futex_atomic_op_inuser(int op, int oparg, int *oval, u32 __user *uaddr)
 		ret = -ENOSYS;
 	}
 
-	pagefault_enable();
-
 	if (!ret)
 		*oval = oldval;
 
diff --git a/arch/parisc/include/asm/futex.h b/arch/parisc/include/asm/futex.h
index d2c3e4106851..c10cc9010cc1 100644
--- a/arch/parisc/include/asm/futex.h
+++ b/arch/parisc/include/asm/futex.h
@@ -39,8 +39,10 @@ arch_futex_atomic_op_inuser(int op, int oparg, int *oval, u32 __user *uaddr)
 	int oldval, ret;
 	u32 tmp;
 
+	if (!access_ok(uaddr, sizeof(u32)))
+		return -EFAULT;
+
 	_futex_spin_lock_irqsave(uaddr, &flags);
-	pagefault_disable();
 
 	ret = -EFAULT;
 	if (unlikely(get_user(oldval, uaddr) != 0))
@@ -73,7 +75,6 @@ arch_futex_atomic_op_inuser(int op, int oparg, int *oval, u32 __user *uaddr)
 		ret = -EFAULT;
 
 out_pagefault_enable:
-	pagefault_enable();
 	_futex_spin_unlock_irqrestore(uaddr, &flags);
 
 	if (!ret)
diff --git a/arch/powerpc/include/asm/futex.h b/arch/powerpc/include/asm/futex.h
index bc7d9d06a6d9..f187bb5e524e 100644
--- a/arch/powerpc/include/asm/futex.h
+++ b/arch/powerpc/include/asm/futex.h
@@ -35,8 +35,9 @@ static inline int arch_futex_atomic_op_inuser(int op, int oparg, int *oval,
 {
 	int oldval = 0, ret;
 
+	if (!access_ok(uaddr, sizeof(u32)))
+		return -EFAULT;
 	allow_read_write_user(uaddr, uaddr, sizeof(*uaddr));
-	pagefault_disable();
 
 	switch (op) {
 	case FUTEX_OP_SET:
@@ -58,8 +59,6 @@ static inline int arch_futex_atomic_op_inuser(int op, int oparg, int *oval,
 		ret = -ENOSYS;
 	}
 
-	pagefault_enable();
-
 	*oval = oldval;
 
 	prevent_read_write_user(uaddr, uaddr, sizeof(*uaddr));
diff --git a/arch/riscv/include/asm/futex.h b/arch/riscv/include/asm/futex.h
index fdfaf7f3df7c..1b00badb9f87 100644
--- a/arch/riscv/include/asm/futex.h
+++ b/arch/riscv/include/asm/futex.h
@@ -46,7 +46,8 @@ arch_futex_atomic_op_inuser(int op, int oparg, int *oval, u32 __user *uaddr)
 {
 	int oldval = 0, ret = 0;
 
-	pagefault_disable();
+	if (!access_ok(uaddr, sizeof(u32)))
+		return -EFAULT;
 
 	switch (op) {
 	case FUTEX_OP_SET:
@@ -73,8 +74,6 @@ arch_futex_atomic_op_inuser(int op, int oparg, int *oval, u32 __user *uaddr)
 		ret = -ENOSYS;
 	}
 
-	pagefault_enable();
-
 	if (!ret)
 		*oval = oldval;
 
diff --git a/arch/s390/include/asm/futex.h b/arch/s390/include/asm/futex.h
index 5e97a4353147..ed965c3ecd5b 100644
--- a/arch/s390/include/asm/futex.h
+++ b/arch/s390/include/asm/futex.h
@@ -28,8 +28,9 @@ static inline int arch_futex_atomic_op_inuser(int op, int oparg, int *oval,
 	int oldval = 0, newval, ret;
 	mm_segment_t old_fs;
 
+	if (!access_ok(uaddr, sizeof(u32)))
+		return -EFAULT;
 	old_fs = enable_sacf_uaccess();
-	pagefault_disable();
 	switch (op) {
 	case FUTEX_OP_SET:
 		__futex_atomic_op("lr %2,%5\n",
@@ -54,7 +55,6 @@ static inline int arch_futex_atomic_op_inuser(int op, int oparg, int *oval,
 	default:
 		ret = -ENOSYS;
 	}
-	pagefault_enable();
 	disable_sacf_uaccess(old_fs);
 
 	if (!ret)
diff --git a/arch/sh/include/asm/futex.h b/arch/sh/include/asm/futex.h
index 3190ec89df81..324fa680b13d 100644
--- a/arch/sh/include/asm/futex.h
+++ b/arch/sh/include/asm/futex.h
@@ -34,7 +34,8 @@ static inline int arch_futex_atomic_op_inuser(int op, u32 oparg, int *oval,
 	u32 oldval, newval, prev;
 	int ret;
 
-	pagefault_disable();
+	if (!access_ok(uaddr, sizeof(u32)))
+		return -EFAULT;
 
 	do {
 		ret = get_user(oldval, uaddr);
@@ -67,8 +68,6 @@ static inline int arch_futex_atomic_op_inuser(int op, u32 oparg, int *oval,
 		ret = futex_atomic_cmpxchg_inatomic(&prev, uaddr, oldval, newval);
 	} while (!ret && prev != oldval);
 
-	pagefault_enable();
-
 	if (!ret)
 		*oval = oldval;
 
diff --git a/arch/sparc/include/asm/futex_64.h b/arch/sparc/include/asm/futex_64.h
index 0865ce77ec00..84fffaaf59d3 100644
--- a/arch/sparc/include/asm/futex_64.h
+++ b/arch/sparc/include/asm/futex_64.h
@@ -35,11 +35,11 @@ static inline int arch_futex_atomic_op_inuser(int op, int oparg, int *oval,
 {
 	int oldval = 0, ret, tem;
 
+	if (!access_ok(uaddr, sizeof(u32)))
+		return -EFAULT;
 	if (unlikely((((unsigned long) uaddr) & 0x3UL)))
 		return -EINVAL;
 
-	pagefault_disable();
-
 	switch (op) {
 	case FUTEX_OP_SET:
 		__futex_cas_op("mov\t%4, %1", ret, oldval, uaddr, oparg);
@@ -60,8 +60,6 @@ static inline int arch_futex_atomic_op_inuser(int op, int oparg, int *oval,
 		ret = -ENOSYS;
 	}
 
-	pagefault_enable();
-
 	if (!ret)
 		*oval = oldval;
 
diff --git a/arch/x86/include/asm/futex.h b/arch/x86/include/asm/futex.h
index 13c83fe97988..6bcd1c1486d9 100644
--- a/arch/x86/include/asm/futex.h
+++ b/arch/x86/include/asm/futex.h
@@ -47,7 +47,8 @@ static inline int arch_futex_atomic_op_inuser(int op, int oparg, int *oval,
 {
 	int oldval = 0, ret, tem;
 
-	pagefault_disable();
+	if (!access_ok(uaddr, sizeof(u32)))
+		return -EFAULT;
 
 	switch (op) {
 	case FUTEX_OP_SET:
@@ -70,8 +71,6 @@ static inline int arch_futex_atomic_op_inuser(int op, int oparg, int *oval,
 		ret = -ENOSYS;
 	}
 
-	pagefault_enable();
-
 	if (!ret)
 		*oval = oldval;
 
diff --git a/arch/xtensa/include/asm/futex.h b/arch/xtensa/include/asm/futex.h
index 964611083224..a1a27b2ea460 100644
--- a/arch/xtensa/include/asm/futex.h
+++ b/arch/xtensa/include/asm/futex.h
@@ -72,7 +72,8 @@ static inline int arch_futex_atomic_op_inuser(int op, int oparg, int *oval,
 #if XCHAL_HAVE_S32C1I || XCHAL_HAVE_EXCLUSIVE
 	int oldval = 0, ret;
 
-	pagefault_disable();
+	if (!access_ok(uaddr, sizeof(u32)))
+		return -EFAULT;
 
 	switch (op) {
 	case FUTEX_OP_SET:
@@ -99,8 +100,6 @@ static inline int arch_futex_atomic_op_inuser(int op, int oparg, int *oval,
 		ret = -ENOSYS;
 	}
 
-	pagefault_enable();
-
 	if (!ret)
 		*oval = oldval;
 
diff --git a/include/asm-generic/futex.h b/include/asm-generic/futex.h
index 02970b11f71f..3eab7ba912fc 100644
--- a/include/asm-generic/futex.h
+++ b/include/asm-generic/futex.h
@@ -33,8 +33,9 @@ arch_futex_atomic_op_inuser(int op, u32 oparg, int *oval, u32 __user *uaddr)
 	int oldval, ret;
 	u32 tmp;
 
+	if (!access_ok(uaddr, sizeof(u32)))
+		return -EFAULT;
 	preempt_disable();
-	pagefault_disable();
 
 	ret = -EFAULT;
 	if (unlikely(get_user(oldval, uaddr) != 0))
@@ -67,7 +68,6 @@ arch_futex_atomic_op_inuser(int op, u32 oparg, int *oval, u32 __user *uaddr)
 		ret = -EFAULT;
 
 out_pagefault_enable:
-	pagefault_enable();
 	preempt_enable();
 
 	if (ret == 0)
diff --git a/kernel/futex.c b/kernel/futex.c
index 0cf84c8664f2..7fdd2c949487 100644
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -1723,10 +1723,9 @@ static int futex_atomic_op_inuser(unsigned int encoded_op, u32 __user *uaddr)
 		oparg = 1 << oparg;
 	}
 
-	if (!access_ok(uaddr, sizeof(u32)))
-		return -EFAULT;
-
+	pagefault_disable();
 	ret = arch_futex_atomic_op_inuser(op, oparg, &oldval, uaddr);
+	pagefault_enable();
 	if (ret)
 		return ret;
 
-- 
2.11.0

[RFC][PATCH v2 2/8] sh: no need of access_ok() in arch_futex_atomic_op_inuser()

[Al Viro]

From: Al Viro <viro@zeniv.linux.org.uk>

everything it uses is doing access_ok() already

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
 arch/sh/include/asm/futex.h | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/arch/sh/include/asm/futex.h b/arch/sh/include/asm/futex.h
index 324fa680b13d..b39cda09fb95 100644
--- a/arch/sh/include/asm/futex.h
+++ b/arch/sh/include/asm/futex.h
@@ -34,9 +34,6 @@ static inline int arch_futex_atomic_op_inuser(int op, u32 oparg, int *oval,
 	u32 oldval, newval, prev;
 	int ret;
 
-	if (!access_ok(uaddr, sizeof(u32)))
-		return -EFAULT;
-
 	do {
 		ret = get_user(oldval, uaddr);
 
-- 
2.11.0

[RFC][PATCH v2 3/8] [parisc, s390, sparc64] no need for access_ok() in futex handling

[Al Viro]

From: Al Viro <viro@zeniv.linux.org.uk>

access_ok() is always true on those

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
 arch/parisc/include/asm/futex.h   | 3 ---
 arch/s390/include/asm/futex.h     | 2 --
 arch/sparc/include/asm/futex_64.h | 2 --
 3 files changed, 7 deletions(-)

diff --git a/arch/parisc/include/asm/futex.h b/arch/parisc/include/asm/futex.h
index c10cc9010cc1..c459f656c8c3 100644
--- a/arch/parisc/include/asm/futex.h
+++ b/arch/parisc/include/asm/futex.h
@@ -39,9 +39,6 @@ arch_futex_atomic_op_inuser(int op, int oparg, int *oval, u32 __user *uaddr)
 	int oldval, ret;
 	u32 tmp;
 
-	if (!access_ok(uaddr, sizeof(u32)))
-		return -EFAULT;
-
 	_futex_spin_lock_irqsave(uaddr, &flags);
 
 	ret = -EFAULT;
diff --git a/arch/s390/include/asm/futex.h b/arch/s390/include/asm/futex.h
index ed965c3ecd5b..26f9144562c9 100644
--- a/arch/s390/include/asm/futex.h
+++ b/arch/s390/include/asm/futex.h
@@ -28,8 +28,6 @@ static inline int arch_futex_atomic_op_inuser(int op, int oparg, int *oval,
 	int oldval = 0, newval, ret;
 	mm_segment_t old_fs;
 
-	if (!access_ok(uaddr, sizeof(u32)))
-		return -EFAULT;
 	old_fs = enable_sacf_uaccess();
 	switch (op) {
 	case FUTEX_OP_SET:
diff --git a/arch/sparc/include/asm/futex_64.h b/arch/sparc/include/asm/futex_64.h
index 84fffaaf59d3..72de967318d7 100644
--- a/arch/sparc/include/asm/futex_64.h
+++ b/arch/sparc/include/asm/futex_64.h
@@ -35,8 +35,6 @@ static inline int arch_futex_atomic_op_inuser(int op, int oparg, int *oval,
 {
 	int oldval = 0, ret, tem;
 
-	if (!access_ok(uaddr, sizeof(u32)))
-		return -EFAULT;
 	if (unlikely((((unsigned long) uaddr) & 0x3UL)))
 		return -EINVAL;
 
-- 
2.11.0

[RFC][PATCH v2 4/8] objtool: whitelist __sanitizer_cov_trace_switch()

[Al Viro]

From: Al Viro <viro@zeniv.linux.org.uk>

it's not really different from e.g. __sanitizer_cov_trace_cmp4();
as it is, the switches that generate an array of labels get
rejected by objtool, while slightly different set of cases
that gets compiled into a series of comparisons is accepted.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
 tools/objtool/check.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 4768d91c6d68..3667c5d7453a 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -478,6 +478,7 @@ static const char *uaccess_safe_builtin[] = {
 	"__sanitizer_cov_trace_cmp2",
 	"__sanitizer_cov_trace_cmp4",
 	"__sanitizer_cov_trace_cmp8",
+	"__sanitizer_cov_trace_switch",
 	/* UBSAN */
 	"ubsan_type_mismatch_common",
 	"__ubsan_handle_type_mismatch",
-- 
2.11.0

[RFC][PATCH v2 5/8] x86: convert arch_futex_atomic_op_inuser() to user_access_begin/user_access_end()

[Al Viro]

From: Al Viro <viro@zeniv.linux.org.uk>

Lift stac/clac pairs from __futex_atomic_op{1,2} into arch_futex_atomic_op_inuser(),
fold them with access_ok() in there.  The switch in arch_futex_atomic_op_inuser()
is what has required the previous (objtool) commit...

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
 arch/x86/include/asm/futex.h | 62 +++++++++++++++++++++++++-------------------
 1 file changed, 36 insertions(+), 26 deletions(-)

diff --git a/arch/x86/include/asm/futex.h b/arch/x86/include/asm/futex.h
index 6bcd1c1486d9..53c07ab63762 100644
--- a/arch/x86/include/asm/futex.h
+++ b/arch/x86/include/asm/futex.h
@@ -12,26 +12,33 @@
 #include <asm/processor.h>
 #include <asm/smap.h>
 
-#define __futex_atomic_op1(insn, ret, oldval, uaddr, oparg)	\
-	asm volatile("\t" ASM_STAC "\n"				\
-		     "1:\t" insn "\n"				\
-		     "2:\t" ASM_CLAC "\n"			\
+#define unsafe_atomic_op1(insn, oval, uaddr, oparg, label)	\
+do {								\
+	int oldval = 0, ret;					\
+	asm volatile("1:\t" insn "\n"				\
+		     "2:\n"					\
 		     "\t.section .fixup,\"ax\"\n"		\
 		     "3:\tmov\t%3, %1\n"			\
 		     "\tjmp\t2b\n"				\
 		     "\t.previous\n"				\
 		     _ASM_EXTABLE_UA(1b, 3b)			\
 		     : "=r" (oldval), "=r" (ret), "+m" (*uaddr)	\
-		     : "i" (-EFAULT), "0" (oparg), "1" (0))
+		     : "i" (-EFAULT), "0" (oparg), "1" (0));	\
+	if (ret)						\
+		goto label;					\
+	*oval = oldval;						\
+} while(0)
 
-#define __futex_atomic_op2(insn, ret, oldval, uaddr, oparg)	\
-	asm volatile("\t" ASM_STAC "\n"				\
-		     "1:\tmovl	%2, %0\n"			\
+
+#define unsafe_atomic_op2(insn, oval, uaddr, oparg, label)	\
+do {								\
+	int oldval = 0, ret, tem;				\
+	asm volatile("1:\tmovl	%2, %0\n"			\
 		     "\tmovl\t%0, %3\n"				\
 		     "\t" insn "\n"				\
 		     "2:\t" LOCK_PREFIX "cmpxchgl %3, %2\n"	\
 		     "\tjnz\t1b\n"				\
-		     "3:\t" ASM_CLAC "\n"			\
+		     "3:\n"					\
 		     "\t.section .fixup,\"ax\"\n"		\
 		     "4:\tmov\t%5, %1\n"			\
 		     "\tjmp\t3b\n"				\
@@ -40,41 +47,44 @@
 		     _ASM_EXTABLE_UA(2b, 4b)			\
 		     : "=&a" (oldval), "=&r" (ret),		\
 		       "+m" (*uaddr), "=&r" (tem)		\
-		     : "r" (oparg), "i" (-EFAULT), "1" (0))
+		     : "r" (oparg), "i" (-EFAULT), "1" (0));	\
+	if (ret)						\
+		goto label;					\
+	*oval = oldval;						\
+} while(0)
 
-static inline int arch_futex_atomic_op_inuser(int op, int oparg, int *oval,
+static __always_inline int arch_futex_atomic_op_inuser(int op, int oparg, int *oval,
 		u32 __user *uaddr)
 {
-	int oldval = 0, ret, tem;
-
-	if (!access_ok(uaddr, sizeof(u32)))
+	if (!user_access_begin(uaddr, sizeof(u32)))
 		return -EFAULT;
 
 	switch (op) {
 	case FUTEX_OP_SET:
-		__futex_atomic_op1("xchgl %0, %2", ret, oldval, uaddr, oparg);
+		unsafe_atomic_op1("xchgl %0, %2", oval, uaddr, oparg, Efault);
 		break;
 	case FUTEX_OP_ADD:
-		__futex_atomic_op1(LOCK_PREFIX "xaddl %0, %2", ret, oldval,
-				   uaddr, oparg);
+		unsafe_atomic_op1(LOCK_PREFIX "xaddl %0, %2", oval,
+				   uaddr, oparg, Efault);
 		break;
 	case FUTEX_OP_OR:
-		__futex_atomic_op2("orl %4, %3", ret, oldval, uaddr, oparg);
+		unsafe_atomic_op2("orl %4, %3", oval, uaddr, oparg, Efault);
 		break;
 	case FUTEX_OP_ANDN:
-		__futex_atomic_op2("andl %4, %3", ret, oldval, uaddr, ~oparg);
+		unsafe_atomic_op2("andl %4, %3", oval, uaddr, ~oparg, Efault);
 		break;
 	case FUTEX_OP_XOR:
-		__futex_atomic_op2("xorl %4, %3", ret, oldval, uaddr, oparg);
+		unsafe_atomic_op2("xorl %4, %3", oval, uaddr, oparg, Efault);
 		break;
 	default:
-		ret = -ENOSYS;
+		user_access_end();
+		return -ENOSYS;
 	}
-
-	if (!ret)
-		*oval = oldval;
-
-	return ret;
+	user_access_end();
+	return 0;
+Efault:
+	user_access_end();
+	return -EFAULT;
 }
 
 static inline int futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr,
-- 
2.11.0

[RFC][PATCH v2 6/8] x86: don't reload after cmpxchg in unsafe_atomic_op2() loop

[Al Viro]

From: Al Viro <viro@zeniv.linux.org.uk>

lock cmpxchg leaves the current value in eax; no need to reload it.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
 arch/x86/include/asm/futex.h | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/arch/x86/include/asm/futex.h b/arch/x86/include/asm/futex.h
index 53c07ab63762..d5d36f408ad0 100644
--- a/arch/x86/include/asm/futex.h
+++ b/arch/x86/include/asm/futex.h
@@ -34,17 +34,17 @@ do {								\
 do {								\
 	int oldval = 0, ret, tem;				\
 	asm volatile("1:\tmovl	%2, %0\n"			\
-		     "\tmovl\t%0, %3\n"				\
+		     "2:\tmovl\t%0, %3\n"			\
 		     "\t" insn "\n"				\
-		     "2:\t" LOCK_PREFIX "cmpxchgl %3, %2\n"	\
-		     "\tjnz\t1b\n"				\
-		     "3:\n"					\
+		     "3:\t" LOCK_PREFIX "cmpxchgl %3, %2\n"	\
+		     "\tjnz\t2b\n"				\
+		     "4:\n"					\
 		     "\t.section .fixup,\"ax\"\n"		\
-		     "4:\tmov\t%5, %1\n"			\
+		     "5:\tmov\t%5, %1\n"			\
 		     "\tjmp\t3b\n"				\
 		     "\t.previous\n"				\
-		     _ASM_EXTABLE_UA(1b, 4b)			\
-		     _ASM_EXTABLE_UA(2b, 4b)			\
+		     _ASM_EXTABLE_UA(1b, 5b)			\
+		     _ASM_EXTABLE_UA(3b, 5b)			\
 		     : "=&a" (oldval), "=&r" (ret),		\
 		       "+m" (*uaddr), "=&r" (tem)		\
 		     : "r" (oparg), "i" (-EFAULT), "1" (0));	\
-- 
2.11.0

Re: [RFC][PATCH v2 6/8] x86: don't reload after cmpxchg in unsafe_atomic_op2() loop

[Linus Torvalds]

On Thu, Mar 26, 2020 at 7:28 PM Al Viro <viro@zeniv.linux.org.uk> wrote:
>
> From: Al Viro <viro@zeniv.linux.org.uk>
>
> lock cmpxchg leaves the current value in eax; no need to reload it.

I think this one is buggy.

Patch edited to remove the "-" lines, so that you see the end result:

>         int oldval = 0, ret, tem;                               \
>         asm volatile("1:\tmovl  %2, %0\n"                       \
> +                    "2:\tmovl\t%0, %3\n"                       \
>                      "\t" insn "\n"                             \
> +                    "3:\t" LOCK_PREFIX "cmpxchgl %3, %2\n"     \
> +                    "\tjnz\t2b\n"                              \
> +                    "4:\n"                                     \
>                      "\t.section .fixup,\"ax\"\n"               \
> +                    "5:\tmov\t%5, %1\n"                        \
>                      "\tjmp\t3b\n"                              \
>                      "\t.previous\n"                            \
> +                    _ASM_EXTABLE_UA(1b, 5b)                    \
> +                    _ASM_EXTABLE_UA(3b, 5b)                    \
>                      : "=&a" (oldval), "=&r" (ret),             \
>                        "+m" (*uaddr), "=&r" (tem)               \
>                      : "r" (oparg), "i" (-EFAULT), "1" (0));    \

I think that

                       "\tjmp\t3b\n"

line in the fixup section should be

                       "\tjmp\t4b\n"

because you don't want to jump to the cmpxchg instruction.

Maybe I'm misreading it.

               Linus

Re: [RFC][PATCH v2 6/8] x86: don't reload after cmpxchg in unsafe_atomic_op2() loop

[Al Viro]

On Thu, Mar 26, 2020 at 08:23:59PM -0700, Linus Torvalds wrote:
> On Thu, Mar 26, 2020 at 7:28 PM Al Viro <viro@zeniv.linux.org.uk> wrote:
> >
> > From: Al Viro <viro@zeniv.linux.org.uk>
> >
> > lock cmpxchg leaves the current value in eax; no need to reload it.
> 
> I think this one is buggy.
> 
> Patch edited to remove the "-" lines, so that you see the end result:
> 
> >         int oldval = 0, ret, tem;                               \
> >         asm volatile("1:\tmovl  %2, %0\n"                       \
> > +                    "2:\tmovl\t%0, %3\n"                       \
> >                      "\t" insn "\n"                             \
> > +                    "3:\t" LOCK_PREFIX "cmpxchgl %3, %2\n"     \
> > +                    "\tjnz\t2b\n"                              \
> > +                    "4:\n"                                     \
> >                      "\t.section .fixup,\"ax\"\n"               \
> > +                    "5:\tmov\t%5, %1\n"                        \
> >                      "\tjmp\t3b\n"                              \
> >                      "\t.previous\n"                            \
> > +                    _ASM_EXTABLE_UA(1b, 5b)                    \
> > +                    _ASM_EXTABLE_UA(3b, 5b)                    \
> >                      : "=&a" (oldval), "=&r" (ret),             \
> >                        "+m" (*uaddr), "=&r" (tem)               \
> >                      : "r" (oparg), "i" (-EFAULT), "1" (0));    \
> 
> I think that
> 
>                        "\tjmp\t3b\n"
> 
> line in the fixup section should be
> 
>                        "\tjmp\t4b\n"
> 
> because you don't want to jump to the cmpxchg instruction.
> 
> Maybe I'm misreading it.

You are not - I'd missed that one while renumbering the labels.  Fixed and
pushed.

[RFC][PATCH v2 7/8] generic arch_futex_atomic_op_inuser() doesn't need access_ok()

[Al Viro]

From: Al Viro <viro@zeniv.linux.org.uk>

uses get_user() and put_user() for memory accesses

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
 include/asm-generic/futex.h | 2 --
 1 file changed, 2 deletions(-)

diff --git a/include/asm-generic/futex.h b/include/asm-generic/futex.h
index 3eab7ba912fc..f4c3470480c7 100644
--- a/include/asm-generic/futex.h
+++ b/include/asm-generic/futex.h
@@ -33,8 +33,6 @@ arch_futex_atomic_op_inuser(int op, u32 oparg, int *oval, u32 __user *uaddr)
 	int oldval, ret;
 	u32 tmp;
 
-	if (!access_ok(uaddr, sizeof(u32)))
-		return -EFAULT;
 	preempt_disable();
 
 	ret = -EFAULT;
-- 
2.11.0

[RFC][PATCH v2 8/8] x86: get rid of user_atomic_cmpxchg_inatomic()

[Al Viro]

From: Al Viro <viro@zeniv.linux.org.uk>

Only one user left; the thing had been made polymorphic back in 2013
for the sake of MPX.  No point keeping it now that MPX is gone.
Convert futex_atomic_cmpxchg_inatomic() to user_access_{begin,end}()
while we are at it.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
 arch/x86/include/asm/futex.h   | 20 ++++++++-
 arch/x86/include/asm/uaccess.h | 93 ------------------------------------------
 2 files changed, 19 insertions(+), 94 deletions(-)

diff --git a/arch/x86/include/asm/futex.h b/arch/x86/include/asm/futex.h
index d5d36f408ad0..537f58280174 100644
--- a/arch/x86/include/asm/futex.h
+++ b/arch/x86/include/asm/futex.h
@@ -90,7 +90,25 @@ static __always_inline int arch_futex_atomic_op_inuser(int op, int oparg, int *o
 static inline int futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr,
 						u32 oldval, u32 newval)
 {
-	return user_atomic_cmpxchg_inatomic(uval, uaddr, oldval, newval);
+	int ret = 0;
+
+	if (!user_access_begin(uaddr, sizeof(u32)))
+		return -EFAULT;
+	asm volatile("\n"
+		"1:\t" LOCK_PREFIX "cmpxchgl %4, %2\n"
+		"2:\n"
+		"\t.section .fixup, \"ax\"\n"
+		"3:\tmov     %3, %0\n"
+		"\tjmp     2b\n"
+		"\t.previous\n"
+		_ASM_EXTABLE_UA(1b, 3b)
+		: "+r" (ret), "=a" (oldval), "+m" (*uaddr)
+		: "i" (-EFAULT), "r" (newval), "1" (oldval)
+		: "memory"
+	);
+	user_access_end();
+	*uval = oldval;
+	return ret;
 }
 
 #endif
diff --git a/arch/x86/include/asm/uaccess.h b/arch/x86/include/asm/uaccess.h
index d11662f753d2..c8247a84244b 100644
--- a/arch/x86/include/asm/uaccess.h
+++ b/arch/x86/include/asm/uaccess.h
@@ -453,99 +453,6 @@ extern __must_check long strnlen_user(const char __user *str, long n);
 unsigned long __must_check clear_user(void __user *mem, unsigned long len);
 unsigned long __must_check __clear_user(void __user *mem, unsigned long len);
 
-extern void __cmpxchg_wrong_size(void)
-	__compiletime_error("Bad argument size for cmpxchg");
-
-#define __user_atomic_cmpxchg_inatomic(uval, ptr, old, new, size)	\
-({									\
-	int __ret = 0;							\
-	__typeof__(*(ptr)) __old = (old);				\
-	__typeof__(*(ptr)) __new = (new);				\
-	__uaccess_begin_nospec();					\
-	switch (size) {							\
-	case 1:								\
-	{								\
-		asm volatile("\n"					\
-			"1:\t" LOCK_PREFIX "cmpxchgb %4, %2\n"		\
-			"2:\n"						\
-			"\t.section .fixup, \"ax\"\n"			\
-			"3:\tmov     %3, %0\n"				\
-			"\tjmp     2b\n"				\
-			"\t.previous\n"					\
-			_ASM_EXTABLE_UA(1b, 3b)				\
-			: "+r" (__ret), "=a" (__old), "+m" (*(ptr))	\
-			: "i" (-EFAULT), "q" (__new), "1" (__old)	\
-			: "memory"					\
-		);							\
-		break;							\
-	}								\
-	case 2:								\
-	{								\
-		asm volatile("\n"					\
-			"1:\t" LOCK_PREFIX "cmpxchgw %4, %2\n"		\
-			"2:\n"						\
-			"\t.section .fixup, \"ax\"\n"			\
-			"3:\tmov     %3, %0\n"				\
-			"\tjmp     2b\n"				\
-			"\t.previous\n"					\
-			_ASM_EXTABLE_UA(1b, 3b)				\
-			: "+r" (__ret), "=a" (__old), "+m" (*(ptr))	\
-			: "i" (-EFAULT), "r" (__new), "1" (__old)	\
-			: "memory"					\
-		);							\
-		break;							\
-	}								\
-	case 4:								\
-	{								\
-		asm volatile("\n"					\
-			"1:\t" LOCK_PREFIX "cmpxchgl %4, %2\n"		\
-			"2:\n"						\
-			"\t.section .fixup, \"ax\"\n"			\
-			"3:\tmov     %3, %0\n"				\
-			"\tjmp     2b\n"				\
-			"\t.previous\n"					\
-			_ASM_EXTABLE_UA(1b, 3b)				\
-			: "+r" (__ret), "=a" (__old), "+m" (*(ptr))	\
-			: "i" (-EFAULT), "r" (__new), "1" (__old)	\
-			: "memory"					\
-		);							\
-		break;							\
-	}								\
-	case 8:								\
-	{								\
-		if (!IS_ENABLED(CONFIG_X86_64))				\
-			__cmpxchg_wrong_size();				\
-									\
-		asm volatile("\n"					\
-			"1:\t" LOCK_PREFIX "cmpxchgq %4, %2\n"		\
-			"2:\n"						\
-			"\t.section .fixup, \"ax\"\n"			\
-			"3:\tmov     %3, %0\n"				\
-			"\tjmp     2b\n"				\
-			"\t.previous\n"					\
-			_ASM_EXTABLE_UA(1b, 3b)				\
-			: "+r" (__ret), "=a" (__old), "+m" (*(ptr))	\
-			: "i" (-EFAULT), "r" (__new), "1" (__old)	\
-			: "memory"					\
-		);							\
-		break;							\
-	}								\
-	default:							\
-		__cmpxchg_wrong_size();					\
-	}								\
-	__uaccess_end();						\
-	*(uval) = __old;						\
-	__ret;								\
-})
-
-#define user_atomic_cmpxchg_inatomic(uval, ptr, old, new)		\
-({									\
-	access_ok((ptr), sizeof(*(ptr))) ?		\
-		__user_atomic_cmpxchg_inatomic((uval), (ptr),		\
-				(old), (new), sizeof(*(ptr))) :		\
-		-EFAULT;						\
-})
-
 /*
  * movsl can be slow when source and dest are not both 8-byte aligned
  */
-- 
2.11.0