[U-Boot] [PATCH v3] x86: lib: Implement standalone __udivdi3 etc instead of libgcc ones
Ferry Toth
ftoth at telfort.nl
Sat Dec 2 17:43:32 UTC 2017
Op Wed, 29 Nov 2017 16:23:31 +0100, schreef Stefan Roese:
> 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.
Thanks Stefan,
Great work, I'll try to test that soon.
BTW I eventually have been able to work around the problem in Yocto. The
work around involved creating a seperate .conf file for u-boot which
includes multilib support. I couldn't add multilib support to my
rootfs .conf file because that broke building the sdk. Of course the
effect is to build a complete seperate target infrastructure (x86_64 +
ml) just to build one binary.
This patch will save people a lot of grief I'm sure.
> The code taken from coreboot is authored from Vadim Bendebury
> <vbendeb at 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 at denx.de>
> Cc: Simon Glass <sjg at chromium.org>
> Cc: Bin Meng <bmeng.cn at gmail.com>
> ---
> v3:
> - Completely get rid of all libgcc references in arch/x86/lib/Makefile,
> also for the standalone applications
>
> v2:
> - Added coreboot git repository link to commit message
>
> arch/x86/config.mk | 3 --
> arch/x86/lib/Makefile | 8 +---
> arch/x86/lib/div64.c | 113
> ++++++++++++++++++++++++++++++++++++++++++++++++++
> arch/x86/lib/gcc.c | 29 -------------
> 4 files changed, 114 insertions(+), 39 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 $(IS_32BIT),elf_i386,elf_x86_64)
>
> -LDFLAGS_FINAL += --wrap=__divdi3 --wrap=__udivdi3 -LDFLAGS_FINAL +=
> --wrap=__moddi3 --wrap=__umoddi3 -
> # This is used in the top-level Makefile which does not include #
> PLATFORM_LDFLAGS LDFLAGS_EFI_PAYLOAD := -Bsymbolic -Bsymbolic-functions
> -shared --no-undefined
> diff --git a/arch/x86/lib/Makefile b/arch/x86/lib/Makefile index
> fe00d7573f..7d729ea0f7 100644 --- a/arch/x86/lib/Makefile +++
> b/arch/x86/lib/Makefile @@ -18,7 +18,6 @@ obj-$(CONFIG_SEABIOS) +=
> coreboot_table.o
> obj-y += early_cmos.o obj-$(CONFIG_EFI) += efi/
> obj-y += e820.o
> -obj-y += gcc.o
> obj-y += init_helpers.o obj-y += interrupts.o obj-y += lpc-
uclass.o
> @@ -49,12 +48,7 @@ endif
> obj-$(CONFIG_HAVE_FSP) += fsp/
> obj-$(CONFIG_SPL_BUILD) += spl.o
>
> -extra-$(CONFIG_USE_PRIVATE_LIBGCC) += lib.a -
> -NORMAL_LIBGCC = $(shell $(CC) $(PLATFORM_CPPFLAGS)
> -print-libgcc-file-name) -OBJCOPYFLAGS := --prefix-symbols=__normal_
> -$(obj)/lib.a: $(NORMAL_LIBGCC) FORCE - $(call if_changed,objcopy)
> +lib-$(CONFIG_USE_PRIVATE_LIBGCC) += div64.o
>
> ifeq ($(CONFIG_$(SPL_)X86_64),)
> obj-$(CONFIG_EFI_APP) += crt0_ia32_efi.o reloc_ia32_efi.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 we
must.
> */ + 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
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