ARM: kvm: implement replacement for ld's LOG2CEIL()

Commit 06f75a1f6200 ("ARM, arm64: kvm: get rid of the bounce
page") uses ld's builtin function LOG2CEIL() to align the
KVM init code to a log2 upper bound of its size. However,
this function turns out to be a fairly recent addition to
binutils, which breaks the build for older toolchains.

So instead, implement a replacement LOG2_ROUNDUP() using
the C preprocessor.

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>

1 files changed, 22 insertions, 2 deletions

diff --git a/arch/arm/kernel/vmlinux.lds.S b/arch/arm/kernel/vmlinux.lds.S
index ba65f1217310..2d760df0d57d 100644
--- a/arch/arm/kernel/vmlinux.lds.S
+++ b/arch/arm/kernel/vmlinux.lds.S
@@ -11,7 +11,27 @@
 #ifdef CONFIG_ARM_KERNMEM_PERMS
 #include <asm/pgtable.h>
 #endif
-        
+
+/*
+ * Poor man's version of LOG2CEIL(), which is
+ * not available in binutils before v2.24.
+ */
+#define LOG2_ROUNDUP(size) (            \
+        __LOG2_ROUNDUP(size,  2)        \
+        __LOG2_ROUNDUP(size,  3)        \
+        __LOG2_ROUNDUP(size,  4)        \
+        __LOG2_ROUNDUP(size,  5)        \
+        __LOG2_ROUNDUP(size,  6)        \
+        __LOG2_ROUNDUP(size,  7)        \
+        __LOG2_ROUNDUP(size,  8)        \
+        __LOG2_ROUNDUP(size,  9)        \
+        __LOG2_ROUNDUP(size, 10)        \
+        __LOG2_ROUNDUP(size, 11)        \
+        12)
+
+#define __LOG2_ROUNDUP(size, order)     \
+        (size) <= (1 << order) ? order :
+
 #define PROC_INFO                                                       \
         . = ALIGN(4);                                                   \
         VMLINUX_SYMBOL(__proc_info_begin) = .;                          \
@@ -23,7 +43,7 @@
         VMLINUX_SYMBOL(__idmap_text_start) = .;                         \
         *(.idmap.text)                                                  \
         VMLINUX_SYMBOL(__idmap_text_end) = .;                           \
-        . = ALIGN(1 << LOG2CEIL(__hyp_idmap_size));                     \
+        . = ALIGN(1 << LOG2_ROUNDUP(__hyp_idmap_size));                 \
         VMLINUX_SYMBOL(__hyp_idmap_text_start) = .;                     \
         *(.hyp.idmap.text)                                              \
         VMLINUX_SYMBOL(__hyp_idmap_text_end) = .;