[PATCH 4.19 66/81] MIPS: Disable Loongson MMI instructions for kernel build

[PATCH 4.19 66/81] MIPS: Disable Loongson MMI instructions for kernel build

[Greg Kroah-Hartman]

From: Paul Burton <paul.burton@mips.com>

commit 2f2b4fd674cadd8c6b40eb629e140a14db4068fd upstream.

GCC 9.x automatically enables support for Loongson MMI instructions when
using some -march= flags, and then errors out when -msoft-float is
specified with:

  cc1: error: ‘-mloongson-mmi’ must be used with ‘-mhard-float’

The kernel shouldn't be using these MMI instructions anyway, just as it
doesn't use floating point instructions. Explicitly disable them in
order to fix the build with GCC 9.x.

Signed-off-by: Paul Burton <paul.burton@mips.com>
Fixes: 3702bba5eb4f ("MIPS: Loongson: Add GCC 4.4 support for Loongson2E")
Fixes: 6f7a251a259e ("MIPS: Loongson: Add basic Loongson 2F support")
Fixes: 5188129b8c9f ("MIPS: Loongson-3: Improve -march option and move it to Platform")
Cc: Huacai Chen <chenhc@lemote.com>
Cc: Jiaxun Yang <jiaxun.yang@flygoat.com>
Cc: stable@vger.kernel.org # v2.6.32+
Cc: linux-mips@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 arch/mips/loongson64/Platform |    4 ++++
 arch/mips/vdso/Makefile       |    1 +
 2 files changed, 5 insertions(+)

--- a/arch/mips/loongson64/Platform
+++ b/arch/mips/loongson64/Platform
@@ -43,6 +43,10 @@ else
       $(call cc-option,-march=mips64r2,-mips64r2 -U_MIPS_ISA -D_MIPS_ISA=_MIPS_ISA_MIPS64)
 endif
 
+# Some -march= flags enable MMI instructions, and GCC complains about that
+# support being enabled alongside -msoft-float. Thus explicitly disable MMI.
+cflags-y += $(call cc-option,-mno-loongson-mmi)
+
 #
 # Loongson Machines' Support
 #
--- a/arch/mips/vdso/Makefile
+++ b/arch/mips/vdso/Makefile
@@ -9,6 +9,7 @@ ccflags-vdso := \
 	$(filter -mmicromips,$(KBUILD_CFLAGS)) \
 	$(filter -march=%,$(KBUILD_CFLAGS)) \
 	$(filter -m%-float,$(KBUILD_CFLAGS)) \
+	$(filter -mno-loongson-%,$(KBUILD_CFLAGS)) \
 	-D__VDSO__
 
 ifeq ($(cc-name),clang)

Re: [PATCH 4.19 66/81] MIPS: Disable Loongson MMI instructions for kernel build

[Guenter Roeck]

Hi,

On Wed, Oct 16, 2019 at 02:51:17PM -0700, Greg Kroah-Hartman wrote:
> From: Paul Burton <paul.burton@mips.com>
> 
> commit 2f2b4fd674cadd8c6b40eb629e140a14db4068fd upstream.
> 
> GCC 9.x automatically enables support for Loongson MMI instructions when
> using some -march= flags, and then errors out when -msoft-float is
> specified with:
> 
>   cc1: error: ‘-mloongson-mmi’ must be used with ‘-mhard-float’
> 
> The kernel shouldn't be using these MMI instructions anyway, just as it
> doesn't use floating point instructions. Explicitly disable them in
> order to fix the build with GCC 9.x.
> 

I still see this problem when trying to compile fuloong2e_defconfig with
gcc 9.x or later. Reason seems to be that the patch was applied to
arch/mips/loongson64/Platform, but fuloong2e_defconfig uses
arch/mips/loongson2ef/Platform.

Am I missing something ?

Thanks,
Guenter

Re: [PATCH 4.19 66/81] MIPS: Disable Loongson MMI instructions for kernel build

[Greg Kroah-Hartman]

On Wed, Aug 26, 2020 at 02:06:28PM -0700, Guenter Roeck wrote:
> Hi,
> 
> On Wed, Oct 16, 2019 at 02:51:17PM -0700, Greg Kroah-Hartman wrote:
> > From: Paul Burton <paul.burton@mips.com>
> > 
> > commit 2f2b4fd674cadd8c6b40eb629e140a14db4068fd upstream.
> > 
> > GCC 9.x automatically enables support for Loongson MMI instructions when
> > using some -march= flags, and then errors out when -msoft-float is
> > specified with:
> > 
> >   cc1: error: ‘-mloongson-mmi’ must be used with ‘-mhard-float’
> > 
> > The kernel shouldn't be using these MMI instructions anyway, just as it
> > doesn't use floating point instructions. Explicitly disable them in
> > order to fix the build with GCC 9.x.
> > 
> 
> I still see this problem when trying to compile fuloong2e_defconfig with
> gcc 9.x or later. Reason seems to be that the patch was applied to
> arch/mips/loongson64/Platform, but fuloong2e_defconfig uses
> arch/mips/loongson2ef/Platform.
> 
> Am I missing something ?

I don't know, sorry, that would be something that Paul understands.

Paul?

Re: [PATCH 4.19 66/81] MIPS: Disable Loongson MMI instructions for kernel build

[Philippe Mathieu-Daudé]

On Thu, Sep 3, 2020 at 11:28 AM Greg Kroah-Hartman
<gregkh@linuxfoundation.org> wrote:
>
> On Wed, Aug 26, 2020 at 02:06:28PM -0700, Guenter Roeck wrote:
> > Hi,
> >
> > On Wed, Oct 16, 2019 at 02:51:17PM -0700, Greg Kroah-Hartman wrote:
> > > From: Paul Burton <paul.burton@mips.com>
> > >
> > > commit 2f2b4fd674cadd8c6b40eb629e140a14db4068fd upstream.
> > >
> > > GCC 9.x automatically enables support for Loongson MMI instructions when
> > > using some -march= flags, and then errors out when -msoft-float is
> > > specified with:
> > >
> > >   cc1: error: ‘-mloongson-mmi’ must be used with ‘-mhard-float’
> > >
> > > The kernel shouldn't be using these MMI instructions anyway, just as it
> > > doesn't use floating point instructions. Explicitly disable them in
> > > order to fix the build with GCC 9.x.
> > >
> >
> > I still see this problem when trying to compile fuloong2e_defconfig with
> > gcc 9.x or later. Reason seems to be that the patch was applied to
> > arch/mips/loongson64/Platform, but fuloong2e_defconfig uses
> > arch/mips/loongson2ef/Platform.
> >
> > Am I missing something ?
>
> I don't know, sorry, that would be something that Paul understands.
>
> Paul?

Cc'ing Thomas who now maintains this.

Re: [PATCH 4.19 66/81] MIPS: Disable Loongson MMI instructions for kernel build

[Thomas Bogendoerfer]

On Mon, Sep 07, 2020 at 05:35:26AM +0200, Philippe Mathieu-Daudé wrote:
> On Thu, Sep 3, 2020 at 11:28 AM Greg Kroah-Hartman
> <gregkh@linuxfoundation.org> wrote:
> >
> > On Wed, Aug 26, 2020 at 02:06:28PM -0700, Guenter Roeck wrote:
> > > Hi,
> > >
> > > On Wed, Oct 16, 2019 at 02:51:17PM -0700, Greg Kroah-Hartman wrote:
> > > > From: Paul Burton <paul.burton@mips.com>
> > > >
> > > > commit 2f2b4fd674cadd8c6b40eb629e140a14db4068fd upstream.
> > > >
> > > > GCC 9.x automatically enables support for Loongson MMI instructions when
> > > > using some -march= flags, and then errors out when -msoft-float is
> > > > specified with:
> > > >
> > > >   cc1: error: ‘-mloongson-mmi’ must be used with ‘-mhard-float’
> > > >
> > > > The kernel shouldn't be using these MMI instructions anyway, just as it
> > > > doesn't use floating point instructions. Explicitly disable them in
> > > > order to fix the build with GCC 9.x.
> > > >
> > >
> > > I still see this problem when trying to compile fuloong2e_defconfig with
> > > gcc 9.x or later. Reason seems to be that the patch was applied to
> > > arch/mips/loongson64/Platform, but fuloong2e_defconfig uses
> > > arch/mips/loongson2ef/Platform.
> > >
> > > Am I missing something ?
> >
> > I don't know, sorry, that would be something that Paul understands.
> >
> > Paul?
> 
> Cc'ing Thomas who now maintains this.

I've queued a patch to fix this in mips-fixes.

Thomas.

-- 
Crap can work. Given enough thrust pigs will fly, but it's not necessarily a
good idea.                                                [ RFC1925, 2.3 ]

[PATCH 4.19 67/81] MIPS: elf_hwcap: Export userspace ASEs

[Greg Kroah-Hartman]

From: Jiaxun Yang <jiaxun.yang@flygoat.com>

commit 38dffe1e4dde1d3174fdce09d67370412843ebb5 upstream.

A Golang developer reported MIPS hwcap isn't reflecting instructions
that the processor actually supported so programs can't apply optimized
code at runtime.

Thus we export the ASEs that can be used in userspace programs.

Reported-by: Meng Zhuo <mengzhuo1203@gmail.com>
Signed-off-by: Jiaxun Yang <jiaxun.yang@flygoat.com>
Cc: linux-mips@vger.kernel.org
Cc: Paul Burton <paul.burton@mips.com>
Cc: <stable@vger.kernel.org> # 4.14+
Signed-off-by: Paul Burton <paul.burton@mips.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 arch/mips/include/uapi/asm/hwcap.h |   11 +++++++++++
 arch/mips/kernel/cpu-probe.c       |   33 +++++++++++++++++++++++++++++++++
 2 files changed, 44 insertions(+)

--- a/arch/mips/include/uapi/asm/hwcap.h
+++ b/arch/mips/include/uapi/asm/hwcap.h
@@ -6,5 +6,16 @@
 #define HWCAP_MIPS_R6		(1 << 0)
 #define HWCAP_MIPS_MSA		(1 << 1)
 #define HWCAP_MIPS_CRC32	(1 << 2)
+#define HWCAP_MIPS_MIPS16	(1 << 3)
+#define HWCAP_MIPS_MDMX     (1 << 4)
+#define HWCAP_MIPS_MIPS3D   (1 << 5)
+#define HWCAP_MIPS_SMARTMIPS (1 << 6)
+#define HWCAP_MIPS_DSP      (1 << 7)
+#define HWCAP_MIPS_DSP2     (1 << 8)
+#define HWCAP_MIPS_DSP3     (1 << 9)
+#define HWCAP_MIPS_MIPS16E2 (1 << 10)
+#define HWCAP_LOONGSON_MMI  (1 << 11)
+#define HWCAP_LOONGSON_EXT  (1 << 12)
+#define HWCAP_LOONGSON_EXT2 (1 << 13)
 
 #endif /* _UAPI_ASM_HWCAP_H */
--- a/arch/mips/kernel/cpu-probe.c
+++ b/arch/mips/kernel/cpu-probe.c
@@ -2105,6 +2105,39 @@ void cpu_probe(void)
 		elf_hwcap |= HWCAP_MIPS_MSA;
 	}
 
+	if (cpu_has_mips16)
+		elf_hwcap |= HWCAP_MIPS_MIPS16;
+
+	if (cpu_has_mdmx)
+		elf_hwcap |= HWCAP_MIPS_MDMX;
+
+	if (cpu_has_mips3d)
+		elf_hwcap |= HWCAP_MIPS_MIPS3D;
+
+	if (cpu_has_smartmips)
+		elf_hwcap |= HWCAP_MIPS_SMARTMIPS;
+
+	if (cpu_has_dsp)
+		elf_hwcap |= HWCAP_MIPS_DSP;
+
+	if (cpu_has_dsp2)
+		elf_hwcap |= HWCAP_MIPS_DSP2;
+
+	if (cpu_has_dsp3)
+		elf_hwcap |= HWCAP_MIPS_DSP3;
+
+	if (cpu_has_mips16e2)
+		elf_hwcap |= HWCAP_MIPS_MIPS16E2;
+
+	if (cpu_has_loongson_mmi)
+		elf_hwcap |= HWCAP_LOONGSON_MMI;
+
+	if (cpu_has_loongson_ext)
+		elf_hwcap |= HWCAP_LOONGSON_EXT;
+
+	if (cpu_has_loongson_ext2)
+		elf_hwcap |= HWCAP_LOONGSON_EXT2;
+
 	if (cpu_has_vz)
 		cpu_probe_vz(c);