From: ard.biesheuvel@linaro.org (Ard Biesheuvel)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH] ARM: kvm: implement replacement for ld's LOG2CEIL()
Date: Mon, 23 Mar 2015 11:52:57 +0100 [thread overview]
Message-ID: <1427107977-18591-1-git-send-email-ard.biesheuvel@linaro.org> (raw)
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>
---
Linker map output after applying this patch:
0xc09a2590 __idmap_text_end = .
[...]
*fill* 0xc09a2590 0x70
0xc09a2600 __hyp_idmap_text_start = .
*(.hyp.idmap.text)
.hyp.idmap.text
0xc09a2600 0x100 arch/arm/kvm/built-in.o
0xc09a2600 __kvm_hyp_init
0xc09a26ec __kvm_hyp_init_end
0xc09a2700 __hyp_idmap_text_end = .
which confirms that the alignemnt is correct. The size of the region
is 0xec bytes, and 0x70 bytes of padding are emitted to align it at
a 0x100 byte boundary
arch/arm/kernel/vmlinux.lds.S | 24 ++++++++++++++++++++++--
1 file 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) = .;
--
1.8.3.2
next reply other threads:[~2015-03-23 10:52 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-03-23 10:52 Ard Biesheuvel [this message]
2015-03-23 11:40 ` [PATCH] ARM: kvm: implement replacement for ld's LOG2CEIL() Will Deacon
2015-03-23 16:03 ` Ard Biesheuvel
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