Re: [PATCH] MIPS: use generic GCC library routines from lib/

[Antony Pavlov]

On Wed, 17 Jan 2018 17:34:59 -0800 (PST)
Palmer Dabbelt <palmer@xxxxxxxxxx> wrote:

> Ah, thanks for reminding me -- I'd originally posted a patch set that converted 
> every other port to use these routines, but I ended up dropping all those.  
> Here's my original MIPS attempt
> 
>     https://marc.info/?l=linux-mips&m=149677651707103&w=2

Now I see that I have dubbed your June 2017 patch. Sorry!

Alas in June 2017 there was no chance to push your patch to linux-mips repo.
Linus merged your patches in November 2017. Ralf merged your RISC-V changes
into linux-mips repo AFAIR just several days ago.

> Given that, I think you can also drop arch/mips/lib/libgcc.h -- if it's used 
> from anywhere else, it should be possible to use include/linux/libgcc.h 
> instead.

I agree with you.

> 
> Assuming it still seems sane do to that I can go give the rest of the patch set 
> another shot.  I'm a bit new to this, but I think I should do something like
> 
> Reviewed-by: Palmer Dabbelt <palmer@xxxxxxxxxx>

I suppose that it's better to resurrect you patch and abandon my patch.

Your original patch series (https://www.linux-mips.org/archives/linux-mips/2017-06/msg00148.html)
has a disadvantage: it tries to change several architectures at once.

I propose to create new short separate patch series for MIPS architecture.

This patch series should contain two patches:

   [PATCH 1/2] Add notrace to lib/ucmpdi2.c
   [PATCH 2/2] MIPS: Use generic libgcc intrinsics


> Thanks!
> 
> On Tue, 16 Jan 2018 22:51:21 PST (-0800), antonynpavlov@xxxxxxxxx wrote:
> > The commit b35cd9884fa5 ("lib: Add shared copies of
> > some GCC library routines") makes it possible
> > to share generic GCC library routines by several
> > architectures.
> >
> > This commit removes several generic GCC library
> > routines from arch/mips/lib/ in favour of similar
> > routines from lib/.
> >
> > Signed-off-by: Antony Pavlov <antonynpavlov@xxxxxxxxx>
> > Cc: Palmer Dabbelt <palmer@xxxxxxxxxx>
> > Cc: Ralf Baechle <ralf@xxxxxxxxxxxxxx>
> > Cc: linux-mips@xxxxxxxxxxxxxx
> > Cc: linux-kernel@xxxxxxxxxxxxxxx
> > ---
> >  arch/mips/Kconfig       |  5 +++++
> >  arch/mips/lib/Makefile  |  2 +-
> >  arch/mips/lib/ashldi3.c | 30 ------------------------------
> >  arch/mips/lib/ashrdi3.c | 32 --------------------------------
> >  arch/mips/lib/cmpdi2.c  | 28 ----------------------------
> >  arch/mips/lib/lshrdi3.c | 30 ------------------------------
> >  arch/mips/lib/ucmpdi2.c | 22 ----------------------
> >  7 files changed, 6 insertions(+), 143 deletions(-)
> >  delete mode 100644 arch/mips/lib/ashldi3.c
> >  delete mode 100644 arch/mips/lib/ashrdi3.c
> >  delete mode 100644 arch/mips/lib/cmpdi2.c
> >  delete mode 100644 arch/mips/lib/lshrdi3.c
> >  delete mode 100644 arch/mips/lib/ucmpdi2.c
> >
> > diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
> > index 350a990fc719..9cd49ee848c6 100644
> > --- a/arch/mips/Kconfig
> > +++ b/arch/mips/Kconfig
> > @@ -73,6 +73,11 @@ config MIPS
> >  	select RTC_LIB if !MACH_LOONGSON64
> >  	select SYSCTL_EXCEPTION_TRACE
> >  	select VIRT_TO_BUS
> > +	select GENERIC_ASHLDI3
> > +	select GENERIC_ASHRDI3
> > +	select GENERIC_LSHRDI3
> > +	select GENERIC_CMPDI2
> > +	select GENERIC_UCMPDI2
> >
> >  menu "Machine selection"
> >
> > diff --git a/arch/mips/lib/Makefile b/arch/mips/lib/Makefile
> > index 78c2affeabf8..195ab4cb0840 100644
> > --- a/arch/mips/lib/Makefile
> > +++ b/arch/mips/lib/Makefile
> > @@ -16,4 +16,4 @@ obj-$(CONFIG_CPU_R3000)		+= r3k_dump_tlb.o
> >  obj-$(CONFIG_CPU_TX39XX)	+= r3k_dump_tlb.o
> >
> >  # libgcc-style stuff needed in the kernel
> > -obj-y += ashldi3.o ashrdi3.o bswapsi.o bswapdi.o cmpdi2.o lshrdi3.o ucmpdi2.o
> > +obj-y += bswapsi.o bswapdi.o
> > diff --git a/arch/mips/lib/ashldi3.c b/arch/mips/lib/ashldi3.c
> > deleted file mode 100644
> > index 24cd6903e797..000000000000
> > --- a/arch/mips/lib/ashldi3.c
> > +++ /dev/null
> > @@ -1,30 +0,0 @@
> > -// SPDX-License-Identifier: GPL-2.0
> > -#include <linux/export.h>
> > -
> > -#include "libgcc.h"
> > -
> > -long long notrace __ashldi3(long long u, word_type b)
> > -{
> > -	DWunion uu, w;
> > -	word_type bm;
> > -
> > -	if (b == 0)
> > -		return u;
> > -
> > -	uu.ll = u;
> > -	bm = 32 - b;
> > -
> > -	if (bm <= 0) {
> > -		w.s.low = 0;
> > -		w.s.high = (unsigned int) uu.s.low << -bm;
> > -	} else {
> > -		const unsigned int carries = (unsigned int) uu.s.low >> bm;
> > -
> > -		w.s.low = (unsigned int) uu.s.low << b;
> > -		w.s.high = ((unsigned int) uu.s.high << b) | carries;
> > -	}
> > -
> > -	return w.ll;
> > -}
> > -
> > -EXPORT_SYMBOL(__ashldi3);
> > diff --git a/arch/mips/lib/ashrdi3.c b/arch/mips/lib/ashrdi3.c
> > deleted file mode 100644
> > index 23f5295af51e..000000000000
> > --- a/arch/mips/lib/ashrdi3.c
> > +++ /dev/null
> > @@ -1,32 +0,0 @@
> > -// SPDX-License-Identifier: GPL-2.0
> > -#include <linux/export.h>
> > -
> > -#include "libgcc.h"
> > -
> > -long long notrace __ashrdi3(long long u, word_type b)
> > -{
> > -	DWunion uu, w;
> > -	word_type bm;
> > -
> > -	if (b == 0)
> > -		return u;
> > -
> > -	uu.ll = u;
> > -	bm = 32 - b;
> > -
> > -	if (bm <= 0) {
> > -		/* w.s.high = 1..1 or 0..0 */
> > -		w.s.high =
> > -		    uu.s.high >> 31;
> > -		w.s.low = uu.s.high >> -bm;
> > -	} else {
> > -		const unsigned int carries = (unsigned int) uu.s.high << bm;
> > -
> > -		w.s.high = uu.s.high >> b;
> > -		w.s.low = ((unsigned int) uu.s.low >> b) | carries;
> > -	}
> > -
> > -	return w.ll;
> > -}
> > -
> > -EXPORT_SYMBOL(__ashrdi3);
> > diff --git a/arch/mips/lib/cmpdi2.c b/arch/mips/lib/cmpdi2.c
> > deleted file mode 100644
> > index 93cfc785927d..000000000000
> > --- a/arch/mips/lib/cmpdi2.c
> > +++ /dev/null
> > @@ -1,28 +0,0 @@
> > -// SPDX-License-Identifier: GPL-2.0
> > -#include <linux/export.h>
> > -
> > -#include "libgcc.h"
> > -
> > -word_type notrace __cmpdi2(long long a, long long b)
> > -{
> > -	const DWunion au = {
> > -		.ll = a
> > -	};
> > -	const DWunion bu = {
> > -		.ll = b
> > -	};
> > -
> > -	if (au.s.high < bu.s.high)
> > -		return 0;
> > -	else if (au.s.high > bu.s.high)
> > -		return 2;
> > -
> > -	if ((unsigned int) au.s.low < (unsigned int) bu.s.low)
> > -		return 0;
> > -	else if ((unsigned int) au.s.low > (unsigned int) bu.s.low)
> > -		return 2;
> > -
> > -	return 1;
> > -}
> > -
> > -EXPORT_SYMBOL(__cmpdi2);
> > diff --git a/arch/mips/lib/lshrdi3.c b/arch/mips/lib/lshrdi3.c
> > deleted file mode 100644
> > index 914b971aca3b..000000000000
> > --- a/arch/mips/lib/lshrdi3.c
> > +++ /dev/null
> > @@ -1,30 +0,0 @@
> > -// SPDX-License-Identifier: GPL-2.0
> > -#include <linux/export.h>
> > -
> > -#include "libgcc.h"
> > -
> > -long long notrace __lshrdi3(long long u, word_type b)
> > -{
> > -	DWunion uu, w;
> > -	word_type bm;
> > -
> > -	if (b == 0)
> > -		return u;
> > -
> > -	uu.ll = u;
> > -	bm = 32 - b;
> > -
> > -	if (bm <= 0) {
> > -		w.s.high = 0;
> > -		w.s.low = (unsigned int) uu.s.high >> -bm;
> > -	} else {
> > -		const unsigned int carries = (unsigned int) uu.s.high << bm;
> > -
> > -		w.s.high = (unsigned int) uu.s.high >> b;
> > -		w.s.low = ((unsigned int) uu.s.low >> b) | carries;
> > -	}
> > -
> > -	return w.ll;
> > -}
> > -
> > -EXPORT_SYMBOL(__lshrdi3);
> > diff --git a/arch/mips/lib/ucmpdi2.c b/arch/mips/lib/ucmpdi2.c
> > deleted file mode 100644
> > index c31c78ca4175..000000000000
> > --- a/arch/mips/lib/ucmpdi2.c
> > +++ /dev/null
> > @@ -1,22 +0,0 @@
> > -// SPDX-License-Identifier: GPL-2.0
> > -#include <linux/export.h>
> > -
> > -#include "libgcc.h"
> > -
> > -word_type notrace __ucmpdi2(unsigned long long a, unsigned long long b)
> > -{
> > -	const DWunion au = {.ll = a};
> > -	const DWunion bu = {.ll = b};
> > -
> > -	if ((unsigned int) au.s.high < (unsigned int) bu.s.high)
> > -		return 0;
> > -	else if ((unsigned int) au.s.high > (unsigned int) bu.s.high)
> > -		return 2;
> > -	if ((unsigned int) au.s.low < (unsigned int) bu.s.low)
> > -		return 0;
> > -	else if ((unsigned int) au.s.low > (unsigned int) bu.s.low)
> > -		return 2;
> > -	return 1;
> > -}
> > -
> > -EXPORT_SYMBOL(__ucmpdi2);


-- 
Best regards,
  Antony Pavlov