arm64: Add ASM_BUG()

Currently. we can only use BUG() from C code, though there are
situations where we would like an equivalent mechanism in assembly code.

This patch refactors our BUG() definition such that it can be used in
either C or assembly, in the form of a new ASM_BUG().

The refactoring requires the removal of escape sequences, such as '\n'
and '\t', but these aren't strictly necessary as we can use ';' to
terminate assembler statements.

The low-level assembly is factored out into <asm/asm-bug.h>, with
<asm/bug.h> retained as the C wrapper.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Dave Martin <dave.martin@arm.com>
Cc: James Morse <james.morse@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
(cherry picked from commit db44e9c5ecf1b60336ccfc176b07ba7d81d855e0)

CVE-2017-5753
CVE-2017-5715
CVE-2017-5754

Signed-off-by: Paolo Pisati <paolo.pisati@canonical.com>
Acked-by: Brad Figg <brad.figg@canonical.com>
Acked-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>

diff --git a/arch/arm64/include/asm/asm-bug.h b/arch/arm64/include/asm/asm-bug.h
new file mode 100644 (file)
index 0000000..636e755
--- /dev/null
+++ b/arch/arm64/include/asm/asm-bug.h
@@ -0,0 +1,54 @@
+#ifndef __ASM_ASM_BUG_H
+/*
+ * Copyright (C) 2017  ARM Limited
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+#define __ASM_ASM_BUG_H
+
+#include <asm/brk-imm.h>
+
+#ifdef CONFIG_DEBUG_BUGVERBOSE
+#define _BUGVERBOSE_LOCATION(file, line) __BUGVERBOSE_LOCATION(file, line)
+#define __BUGVERBOSE_LOCATION(file, line)                      \
+               .pushsection .rodata.str,"aMS",@progbits,1;     \
+       2:      .string file;                                   \
+               .popsection;                                    \
+                                                               \
+               .long 2b - 0b;                                  \
+               .short line;
+#else
+#define _BUGVERBOSE_LOCATION(file, line)
+#endif
+
+#ifdef CONFIG_GENERIC_BUG
+
+#define __BUG_ENTRY(flags)                             \
+               .pushsection __bug_table,"aw";          \
+               .align 2;                               \
+       0:      .long 1f - 0b;                          \
+_BUGVERBOSE_LOCATION(__FILE__, __LINE__)               \
+               .short flags;                           \
+               .popsection;                            \
+       1:
+#else
+#define __BUG_ENTRY(flags)
+#endif
+
+#define ASM_BUG_FLAGS(flags)                           \
+       __BUG_ENTRY(flags)                              \
+       brk     BUG_BRK_IMM
+
+#define ASM_BUG()      ASM_BUG_FLAGS(0)
+
+#endif /* __ASM_ASM_BUG_H */

diff --git a/arch/arm64/include/asm/bug.h b/arch/arm64/include/asm/bug.h
index a02a57186f5689b7a3d99869d6770f7705332957..d7dc437527050736e99dd28e2f0b8bd526551a23 100644 (file)
--- a/arch/arm64/include/asm/bug.h
+++ b/arch/arm64/include/asm/bug.h
@@ -18,41 +18,12 @@
 #ifndef _ARCH_ARM64_ASM_BUG_H
 #define _ARCH_ARM64_ASM_BUG_H
 
-#include <asm/brk-imm.h>
+#include <linux/stringify.h>
 
-#ifdef CONFIG_DEBUG_BUGVERBOSE
-#define _BUGVERBOSE_LOCATION(file, line) __BUGVERBOSE_LOCATION(file, line)
-#define __BUGVERBOSE_LOCATION(file, line)                              \
-               ".pushsection .rodata.str,\"aMS\",@progbits,1\n"        \
-       "2:     .string \"" file "\"\n\t"                               \
-               ".popsection\n\t"                                       \
-                                                                       \
-               ".long 2b - 0b\n\t"                                     \
-               ".short " #line "\n\t"
-#else
-#define _BUGVERBOSE_LOCATION(file, line)
-#endif
-
-#ifdef CONFIG_GENERIC_BUG
-
-#define __BUG_ENTRY(flags)                             \
-               ".pushsection __bug_table,\"aw\"\n\t"   \
-               ".align 2\n\t"                          \
-       "0:     .long 1f - 0b\n\t"                      \
-_BUGVERBOSE_LOCATION(__FILE__, __LINE__)               \
-               ".short " #flags "\n\t"                 \
-               ".popsection\n"                         \
-       "1:     "
-#else
-#define __BUG_ENTRY(flags) ""
-#endif
+#include <asm/asm-bug.h>
 
 #define __BUG_FLAGS(flags)                             \
-       asm volatile (                                  \
-               __BUG_ENTRY(flags)                      \
-               "brk %[imm]" :: [imm] "i" (BUG_BRK_IMM) \
-       );
-
+       asm volatile (__stringify(ASM_BUG_FLAGS(flags)));
 
 #define BUG() do {                                     \
        __BUG_FLAGS(0);                                 \