Hi Stefan,
On Mon, Nov 20, 2017 at 6:43 PM, Stefan Roese sr@denx.de wrote:
Hi Bin,
On 20.11.2017 08:24, Bin Meng wrote:
On Fri, Nov 17, 2017 at 2:02 PM, Stefan Roese sr@denx.de wrote:
This patch removes the inclusion of the libgcc math functions and replaces them by functions coded in C, taken from the coreboot project. This makes U-Boot building more independent from the toolchain installed / available on the build system.
The code taken from coreboot is authored from Vadim Bendebury vbendeb@chromium.org on 2014-11-28 and committed with commit ID e63990ef [libpayload: provide basic 64bit division implementation] (coreboot git repository located here [1]).
I modified the code so that its checkpatch clean without any functional changes.
[1] git://github.com/coreboot/coreboot.git
Signed-off-by: Stefan Roese sr@denx.de Cc: Simon Glass sjg@chromium.org Cc: Bin Meng bmeng.cn@gmail.com
v2:
Added coreboot git repository link to commit message
arch/x86/config.mk | 3 -- arch/x86/lib/Makefile | 2 +- arch/x86/lib/div64.c | 113
++++++++++++++++++++++++++++++++++++++++++++++++++ arch/x86/lib/gcc.c | 29 ------------- 4 files changed, 114 insertions(+), 33 deletions(-) create mode 100644 arch/x86/lib/div64.c delete mode 100644 arch/x86/lib/gcc.c
diff --git a/arch/x86/config.mk b/arch/x86/config.mk index 8835dcf36f..472ada5490 100644 --- a/arch/x86/config.mk +++ b/arch/x86/config.mk @@ -34,9 +34,6 @@ PLATFORM_RELFLAGS += -ffunction-sections -fvisibility=hidden PLATFORM_LDFLAGS += -Bsymbolic -Bsymbolic-functions PLATFORM_LDFLAGS += -m $(if $(IS_32BIT),elf_i386,elf_x86_64)
-LDFLAGS_FINAL += --wrap=__divdi3 --wrap=__udivdi3 -LDFLAGS_FINAL += --wrap=__moddi3 --wrap=__umoddi3
- # This is used in the top-level Makefile which does not include # PLATFORM_LDFLAGS LDFLAGS_EFI_PAYLOAD := -Bsymbolic -Bsymbolic-functions -shared
--no-undefined diff --git a/arch/x86/lib/Makefile b/arch/x86/lib/Makefile index fe00d7573f..d9b23f5cc4 100644 --- a/arch/x86/lib/Makefile +++ b/arch/x86/lib/Makefile @@ -18,7 +18,7 @@ obj-$(CONFIG_SEABIOS) += coreboot_table.o obj-y += early_cmos.o obj-$(CONFIG_EFI) += efi/ obj-y += e820.o -obj-y += gcc.o +obj-y += div64.o obj-y += init_helpers.o obj-y += interrupts.o obj-y += lpc-uclass.o diff --git a/arch/x86/lib/div64.c b/arch/x86/lib/div64.c new file mode 100644 index 0000000000..4efed74037 --- /dev/null +++ b/arch/x86/lib/div64.c @@ -0,0 +1,113 @@ +/*
- This file is copied from the coreboot repository as part of
- the libpayload project:
- Copyright 2014 Google Inc.
- SPDX-License-Identifier: BSD-3-Clause
- */
+#include <common.h>
+union overlay64 {
u64 longw;struct {u32 lower;u32 higher;} words;+};
+u64 __ashldi3(u64 num, unsigned int shift) +{
union overlay64 output;output.longw = num;if (shift >= 32) {output.words.higher = output.words.lower << (shift - 32);output.words.lower = 0;} else {if (!shift)return num;output.words.higher = (output.words.higher << shift) |(output.words.lower >> (32 - shift));output.words.lower = output.words.lower << shift;}return output.longw;+}
+u64 __lshrdi3(u64 num, unsigned int shift) +{
union overlay64 output;output.longw = num;if (shift >= 32) {output.words.lower = output.words.higher >> (shift - 32);output.words.higher = 0;} else {if (!shift)return num;output.words.lower = output.words.lower >> shift |(output.words.higher << (32 - shift));output.words.higher = output.words.higher >> shift;}return output.longw;+}
+#define MAX_32BIT_UINT ((((u64)1) << 32) - 1)
+static u64 _64bit_divide(u64 dividend, u64 divider, u64 *rem_p) +{
u64 result = 0;/** If divider is zero - let the rest of the system care about the* exception.*/if (!divider)return 1 / (u32)divider;/* As an optimization, let's not use 64 bit division unless wemust. */
if (dividend <= MAX_32BIT_UINT) {if (divider > MAX_32BIT_UINT) {result = 0;if (rem_p)*rem_p = divider;} else {result = (u32)dividend / (u32)divider;if (rem_p)*rem_p = (u32)dividend % (u32)divider;}return result;}while (divider <= dividend) {u64 locald = divider;u64 limit = __lshrdi3(dividend, 1);int shifts = 0;while (locald <= limit) {shifts++;locald = locald + locald;}result |= __ashldi3(1, shifts);dividend -= locald;}if (rem_p)*rem_p = dividend;return result;+}
+u64 __udivdi3(u64 num, u64 den) +{
return _64bit_divide(num, den, NULL);+}
+u64 __umoddi3(u64 num, u64 den) +{
u64 v = 0;_64bit_divide(num, den, &v);return v;+} diff --git a/arch/x86/lib/gcc.c b/arch/x86/lib/gcc.c deleted file mode 100644 index 3c70d790d4..0000000000 --- a/arch/x86/lib/gcc.c +++ /dev/null @@ -1,29 +0,0 @@ -/*
- This file is part of the coreboot project.
- Copyright (C) 2009 coresystems GmbH
- SPDX-License-Identifier: GPL-2.0
- */
-#ifdef __GNUC__
-/*
- GCC's libgcc handling is quite broken. While the libgcc functions
- are always regparm(0) the code that calls them uses whatever the
- compiler call specifies. Therefore we need a wrapper around those
- functions. See gcc bug PR41055 for more information.
- */
-#define WRAP_LIBGCC_CALL(type, name) \
type __normal_##name(type a, type b) __attribute__((regparm(0)));\
type __wrap_##name(type a, type b); \type __attribute__((no_instrument_function)) \__wrap_##name(type a, type b) \{ return __normal_##name(a, b); }-WRAP_LIBGCC_CALL(long long, __divdi3) -WRAP_LIBGCC_CALL(unsigned long long, __udivdi3) -WRAP_LIBGCC_CALL(long long, __moddi3) -WRAP_LIBGCC_CALL(unsigned long long, __umoddi3)
-#endif
I don't see __divdi3 and __moddi3 in the new implementation. Are they not needed?
Yes, at least I couldn't find any problems compiling U-Boot for x86 with this patch.
BTW: The code size also did shrink a bit with this patch.
But this is needed in fact. If you write some codes doing signed 64-bit integer division, you will get link errors.
undefined reference to `__divdi3'
Regards, Bin