ARM: 9180/1: Thumb2: align ALT_UP() sections in modules sufficiently

When building for Thumb2, the .alt.smp.init sections that are emitted by
the ALT_UP() patching code may not be 32-bit aligned, even though the
fixup_smp_on_up() routine expects that. This results in alignment faults
at module load time, which need to be fixed up by the fault handler.

So let's align those sections explicitly, and prevent this from occurring.

Cc: <stable@vger.kernel.org>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>

diff --git a/arch/arm/include/asm/assembler.h b/arch/arm/include/asm/assembler.h
index 7d23d4b..6fe6796 100644 (file)
--- a/arch/arm/include/asm/assembler.h
+++ b/arch/arm/include/asm/assembler.h
@@ -288,6 +288,7 @@
  */
 #define ALT_UP(instr...)                                       \
        .pushsection ".alt.smp.init", "a"                       ;\
+       .align  2                                               ;\
        .long   9998b - .                                       ;\
 9997:  instr                                                   ;\
        .if . - 9997b == 2                                      ;\
@@ -299,6 +300,7 @@
        .popsection
 #define ALT_UP_B(label)                                        \
        .pushsection ".alt.smp.init", "a"                       ;\
+       .align  2                                               ;\
        .long   9998b - .                                       ;\
        W(b)    . + (label - 9998b)                                     ;\
        .popsection

diff --git a/arch/arm/include/asm/processor.h b/arch/arm/include/asm/processor.h
index 6af68ed..bdc35c0 100644 (file)
--- a/arch/arm/include/asm/processor.h
+++ b/arch/arm/include/asm/processor.h
@@ -96,6 +96,7 @@ unsigned long __get_wchan(struct task_struct *p);
 #define __ALT_SMP_ASM(smp, up)                                         \
        "9998:  " smp "\n"                                              \
        "       .pushsection \".alt.smp.init\", \"a\"\n"                \
+       "       .align  2\n"                                            \
        "       .long   9998b - .\n"                                    \
        "       " up "\n"                                               \
        "       .popsection\n"