[U-Boot] [PATCH v3] x86: lib: Implement standalone __udivdi3 etc instead of libgcc ones

[U-Boot] [PATCH v3] x86: lib: Implement standalone __udivdi3 etc instead of libgcc ones

[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.

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>
---
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
-- 
2.15.0

[U-Boot] [PATCH v3] x86: lib: Implement standalone __udivdi3 etc instead of libgcc ones

[Bin Meng]

On Wed, Nov 29, 2017 at 11:23 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>
> ---
> 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
>

Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Tested-by: Bin Meng <bmeng.cn@gmail.com>

[U-Boot] [PATCH v3] x86: lib: Implement standalone __udivdi3 etc instead of libgcc ones

[Bin Meng]

On Thu, Nov 30, 2017 at 1:31 PM, Bin Meng <bmeng.cn@gmail.com> wrote:
> On Wed, Nov 29, 2017 at 11:23 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>
>> ---
>> 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
>>
>
> Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
> Tested-by: Bin Meng <bmeng.cn@gmail.com>

applied to u-boot-x86, thanks!

[U-Boot] [PATCH v3] x86: lib: Implement standalone __udivdi3 etc instead of libgcc ones

[Ferry Toth]

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@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>
> ---
> 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