Crash in -next due to 'MIPS: Move FP usage checks into protected_{save, restore}_fp_context'

Crash in -next due to 'MIPS: Move FP usage checks into protected_{save, restore}_fp_context'

[Guenter Roeck]

Hi,

my qemu test for mipsel crashes with next-20150715 as follows.

...
Btrfs loaded
console [netcon0] enabled
netconsole: network logging started
Freeing unused kernel memory: 284K (808f9000 - 80940000)
Kernel panic - not syncing: Attempted to kill init! exitcode=0x00000008

Bisect points to commit 'MIPS: Move FP usage checks into protected_{save,
restore}_fp_context'. Bisect log is as follows.

The problem is not seen with bit endian qemu test.

Please let me know if there is anything I can do to help debugging
this problem.

Thanks,
Guenter
---

# bad: [f4d61b2d73c1e4964ad68df238af5005485469af] Add linux-next specific files for 20150715
# good: [bc0195aad0daa2ad5b0d76cce22b167bc3435590] Linux 4.2-rc2
git bisect start 'HEAD' 'v4.2-rc2'
# bad: [897f492ee766d354b949f3838cbfda8978cfd3cd] Merge remote-tracking branch 'crypto/master'
git bisect bad 897f492ee766d354b949f3838cbfda8978cfd3cd
# bad: [687fe9993e4fbe728113086eb9525360465694e6] Merge remote-tracking branch 'mips/mips-for-linux-next'
git bisect bad 687fe9993e4fbe728113086eb9525360465694e6
# good: [a06e5ae4e8d6d5846809e94d0d45afcc5a9eaf35] Merge remote-tracking branch 'omap/for-next'
git bisect good a06e5ae4e8d6d5846809e94d0d45afcc5a9eaf35
# good: [badbfaedef0876d3cffb3264512aaec8cc162c61] Merge remote-tracking branch 'tegra/for-next'
git bisect good badbfaedef0876d3cffb3264512aaec8cc162c61
# bad: [88841d986cebe1207a47cd7422f5069b2616b194] MIPS: Advertise MSA support via HWCAP when present
git bisect bad 88841d986cebe1207a47cd7422f5069b2616b194
# good: [7c1f7b83170bc14a3e461a9b5595fcecf857da70] MIPS: octeon: Replace the homebrewn flow handler
git bisect good 7c1f7b83170bc14a3e461a9b5595fcecf857da70
# good: [186a699fdf6f0866ca980bcf5e79f54922fe52c2] MIPS: Introduce accessors for MSA vector registers
git bisect good 186a699fdf6f0866ca980bcf5e79f54922fe52c2
# bad: [1793cdaa84ed5c4025a36793f350b07b49555b57] MIPS: Skip odd double FP registers when copying FP32 sigcontext
git bisect bad 1793cdaa84ed5c4025a36793f350b07b49555b57
# good: [8a6bb0ab74eaca5f2a4e60f94df2ea5b08cdfd63] MIPS: Simplify EVA FP context handling code
git bisect good 8a6bb0ab74eaca5f2a4e60f94df2ea5b08cdfd63
# good: [6f47ebd751531249fe0e2b4d3afdfcbf9f66dbd8] MIPS: Use struct mips_abi offsets to save FP context
git bisect good 6f47ebd751531249fe0e2b4d3afdfcbf9f66dbd8
# bad: [fa3156ca734cb65f23df0f844433e75ea1da37f3] MIPS: Move FP usage checks into protected_{save, restore}_fp_context
git bisect bad fa3156ca734cb65f23df0f844433e75ea1da37f3
# first bad commit: [fa3156ca734cb65f23df0f844433e75ea1da37f3] MIPS: Move FP usage checks into protected_{save, restore}_fp_context

Re: Crash in -next due to 'MIPS: Move FP usage checks into protected_{save, restore}_fp_context'

[Guenter Roeck]

On Wed, Jul 15, 2015 at 09:09:18AM -0700, Guenter Roeck wrote:
> Hi,
> 
> my qemu test for mipsel crashes with next-20150715 as follows.
> 
ping ... problem is still seen as of next-20150727.

> ...
> Btrfs loaded
> console [netcon0] enabled
> netconsole: network logging started
> Freeing unused kernel memory: 284K (808f9000 - 80940000)
> Kernel panic - not syncing: Attempted to kill init! exitcode=0x00000008
> 
> Bisect points to commit 'MIPS: Move FP usage checks into protected_{save,
> restore}_fp_context'. Bisect log is as follows.
> 
> The problem is not seen with bit endian qemu test.
> 
> Please let me know if there is anything I can do to help debugging
> this problem.
> 
> Thanks,
> Guenter
> ---
> 
> # bad: [f4d61b2d73c1e4964ad68df238af5005485469af] Add linux-next specific files for 20150715
> # good: [bc0195aad0daa2ad5b0d76cce22b167bc3435590] Linux 4.2-rc2
> git bisect start 'HEAD' 'v4.2-rc2'
> # bad: [897f492ee766d354b949f3838cbfda8978cfd3cd] Merge remote-tracking branch 'crypto/master'
> git bisect bad 897f492ee766d354b949f3838cbfda8978cfd3cd
> # bad: [687fe9993e4fbe728113086eb9525360465694e6] Merge remote-tracking branch 'mips/mips-for-linux-next'
> git bisect bad 687fe9993e4fbe728113086eb9525360465694e6
> # good: [a06e5ae4e8d6d5846809e94d0d45afcc5a9eaf35] Merge remote-tracking branch 'omap/for-next'
> git bisect good a06e5ae4e8d6d5846809e94d0d45afcc5a9eaf35
> # good: [badbfaedef0876d3cffb3264512aaec8cc162c61] Merge remote-tracking branch 'tegra/for-next'
> git bisect good badbfaedef0876d3cffb3264512aaec8cc162c61
> # bad: [88841d986cebe1207a47cd7422f5069b2616b194] MIPS: Advertise MSA support via HWCAP when present
> git bisect bad 88841d986cebe1207a47cd7422f5069b2616b194
> # good: [7c1f7b83170bc14a3e461a9b5595fcecf857da70] MIPS: octeon: Replace the homebrewn flow handler
> git bisect good 7c1f7b83170bc14a3e461a9b5595fcecf857da70
> # good: [186a699fdf6f0866ca980bcf5e79f54922fe52c2] MIPS: Introduce accessors for MSA vector registers
> git bisect good 186a699fdf6f0866ca980bcf5e79f54922fe52c2
> # bad: [1793cdaa84ed5c4025a36793f350b07b49555b57] MIPS: Skip odd double FP registers when copying FP32 sigcontext
> git bisect bad 1793cdaa84ed5c4025a36793f350b07b49555b57
> # good: [8a6bb0ab74eaca5f2a4e60f94df2ea5b08cdfd63] MIPS: Simplify EVA FP context handling code
> git bisect good 8a6bb0ab74eaca5f2a4e60f94df2ea5b08cdfd63
> # good: [6f47ebd751531249fe0e2b4d3afdfcbf9f66dbd8] MIPS: Use struct mips_abi offsets to save FP context
> git bisect good 6f47ebd751531249fe0e2b4d3afdfcbf9f66dbd8
> # bad: [fa3156ca734cb65f23df0f844433e75ea1da37f3] MIPS: Move FP usage checks into protected_{save, restore}_fp_context
> git bisect bad fa3156ca734cb65f23df0f844433e75ea1da37f3
> # first bad commit: [fa3156ca734cb65f23df0f844433e75ea1da37f3] MIPS: Move FP usage checks into protected_{save, restore}_fp_context

Re: Crash in -next due to 'MIPS: Move FP usage checks into protected_{save, restore}_fp_context'

[Paul Burton]

On Mon, Jul 27, 2015 at 08:06:52AM -0700, Guenter Roeck wrote:
> On Wed, Jul 15, 2015 at 09:09:18AM -0700, Guenter Roeck wrote:
> > Hi,
> > 
> > my qemu test for mipsel crashes with next-20150715 as follows.
> > 
> ping ... problem is still seen as of next-20150727.

Hi Guenter,

Apologies for the delay. Could you share your affected kernel
configuration & which userland you're running?

I've just tested with a malta_defconfig kernel & a buildroot based
initramfs without problems, and things are also fine on my physical
MIPSr6 setups. If you have any directions with which I can reproduce
this problem that would be great.

Thanks,
    Paul

> 
> > ...
> > Btrfs loaded
> > console [netcon0] enabled
> > netconsole: network logging started
> > Freeing unused kernel memory: 284K (808f9000 - 80940000)
> > Kernel panic - not syncing: Attempted to kill init! exitcode=0x00000008
> > 
> > Bisect points to commit 'MIPS: Move FP usage checks into protected_{save,
> > restore}_fp_context'. Bisect log is as follows.
> > 
> > The problem is not seen with bit endian qemu test.
> > 
> > Please let me know if there is anything I can do to help debugging
> > this problem.
> > 
> > Thanks,
> > Guenter
> > ---
> > 
> > # bad: [f4d61b2d73c1e4964ad68df238af5005485469af] Add linux-next specific files for 20150715
> > # good: [bc0195aad0daa2ad5b0d76cce22b167bc3435590] Linux 4.2-rc2
> > git bisect start 'HEAD' 'v4.2-rc2'
> > # bad: [897f492ee766d354b949f3838cbfda8978cfd3cd] Merge remote-tracking branch 'crypto/master'
> > git bisect bad 897f492ee766d354b949f3838cbfda8978cfd3cd
> > # bad: [687fe9993e4fbe728113086eb9525360465694e6] Merge remote-tracking branch 'mips/mips-for-linux-next'
> > git bisect bad 687fe9993e4fbe728113086eb9525360465694e6
> > # good: [a06e5ae4e8d6d5846809e94d0d45afcc5a9eaf35] Merge remote-tracking branch 'omap/for-next'
> > git bisect good a06e5ae4e8d6d5846809e94d0d45afcc5a9eaf35
> > # good: [badbfaedef0876d3cffb3264512aaec8cc162c61] Merge remote-tracking branch 'tegra/for-next'
> > git bisect good badbfaedef0876d3cffb3264512aaec8cc162c61
> > # bad: [88841d986cebe1207a47cd7422f5069b2616b194] MIPS: Advertise MSA support via HWCAP when present
> > git bisect bad 88841d986cebe1207a47cd7422f5069b2616b194
> > # good: [7c1f7b83170bc14a3e461a9b5595fcecf857da70] MIPS: octeon: Replace the homebrewn flow handler
> > git bisect good 7c1f7b83170bc14a3e461a9b5595fcecf857da70
> > # good: [186a699fdf6f0866ca980bcf5e79f54922fe52c2] MIPS: Introduce accessors for MSA vector registers
> > git bisect good 186a699fdf6f0866ca980bcf5e79f54922fe52c2
> > # bad: [1793cdaa84ed5c4025a36793f350b07b49555b57] MIPS: Skip odd double FP registers when copying FP32 sigcontext
> > git bisect bad 1793cdaa84ed5c4025a36793f350b07b49555b57
> > # good: [8a6bb0ab74eaca5f2a4e60f94df2ea5b08cdfd63] MIPS: Simplify EVA FP context handling code
> > git bisect good 8a6bb0ab74eaca5f2a4e60f94df2ea5b08cdfd63
> > # good: [6f47ebd751531249fe0e2b4d3afdfcbf9f66dbd8] MIPS: Use struct mips_abi offsets to save FP context
> > git bisect good 6f47ebd751531249fe0e2b4d3afdfcbf9f66dbd8
> > # bad: [fa3156ca734cb65f23df0f844433e75ea1da37f3] MIPS: Move FP usage checks into protected_{save, restore}_fp_context
> > git bisect bad fa3156ca734cb65f23df0f844433e75ea1da37f3
> > # first bad commit: [fa3156ca734cb65f23df0f844433e75ea1da37f3] MIPS: Move FP usage checks into protected_{save, restore}_fp_context

Re: Crash in -next due to 'MIPS: Move FP usage checks into protected_{save, restore}_fp_context'

[Guenter Roeck]

On Mon, Jul 27, 2015 at 10:21:42AM -0700, Paul Burton wrote:
> On Mon, Jul 27, 2015 at 08:06:52AM -0700, Guenter Roeck wrote:
> > On Wed, Jul 15, 2015 at 09:09:18AM -0700, Guenter Roeck wrote:
> > > Hi,
> > > 
> > > my qemu test for mipsel crashes with next-20150715 as follows.
> > > 
> > ping ... problem is still seen as of next-20150727.
> 
> Hi Guenter,
> 
> Apologies for the delay. Could you share your affected kernel
> configuration & which userland you're running?
> 
> I've just tested with a malta_defconfig kernel & a buildroot based
> initramfs without problems, and things are also fine on my physical
> MIPSr6 setups. If you have any directions with which I can reproduce
> this problem that would be great.
> 
This is with qemu in little endian mode. Big endian works fine.
The configuration, the script to build and run the kernel, 
and the root file system used are are available at
https://github.com/groeck/linux-build-test, in directory
rootfs/mipsel/. The log for the latest build failure is in
http://server.roeck-us.net:8010/builders/qemu-mipsel-next/builds/194/steps/qemubuildcommand/logs/stdio.

Hope this helps,
Guenter


> Thanks,
>     Paul
> 
> > 
> > > ...
> > > Btrfs loaded
> > > console [netcon0] enabled
> > > netconsole: network logging started
> > > Freeing unused kernel memory: 284K (808f9000 - 80940000)
> > > Kernel panic - not syncing: Attempted to kill init! exitcode=0x00000008
> > > 
> > > Bisect points to commit 'MIPS: Move FP usage checks into protected_{save,
> > > restore}_fp_context'. Bisect log is as follows.
> > > 
> > > The problem is not seen with bit endian qemu test.
> > > 
> > > Please let me know if there is anything I can do to help debugging
> > > this problem.
> > > 
> > > Thanks,
> > > Guenter
> > > ---
> > > 
> > > # bad: [f4d61b2d73c1e4964ad68df238af5005485469af] Add linux-next specific files for 20150715
> > > # good: [bc0195aad0daa2ad5b0d76cce22b167bc3435590] Linux 4.2-rc2
> > > git bisect start 'HEAD' 'v4.2-rc2'
> > > # bad: [897f492ee766d354b949f3838cbfda8978cfd3cd] Merge remote-tracking branch 'crypto/master'
> > > git bisect bad 897f492ee766d354b949f3838cbfda8978cfd3cd
> > > # bad: [687fe9993e4fbe728113086eb9525360465694e6] Merge remote-tracking branch 'mips/mips-for-linux-next'
> > > git bisect bad 687fe9993e4fbe728113086eb9525360465694e6
> > > # good: [a06e5ae4e8d6d5846809e94d0d45afcc5a9eaf35] Merge remote-tracking branch 'omap/for-next'
> > > git bisect good a06e5ae4e8d6d5846809e94d0d45afcc5a9eaf35
> > > # good: [badbfaedef0876d3cffb3264512aaec8cc162c61] Merge remote-tracking branch 'tegra/for-next'
> > > git bisect good badbfaedef0876d3cffb3264512aaec8cc162c61
> > > # bad: [88841d986cebe1207a47cd7422f5069b2616b194] MIPS: Advertise MSA support via HWCAP when present
> > > git bisect bad 88841d986cebe1207a47cd7422f5069b2616b194
> > > # good: [7c1f7b83170bc14a3e461a9b5595fcecf857da70] MIPS: octeon: Replace the homebrewn flow handler
> > > git bisect good 7c1f7b83170bc14a3e461a9b5595fcecf857da70
> > > # good: [186a699fdf6f0866ca980bcf5e79f54922fe52c2] MIPS: Introduce accessors for MSA vector registers
> > > git bisect good 186a699fdf6f0866ca980bcf5e79f54922fe52c2
> > > # bad: [1793cdaa84ed5c4025a36793f350b07b49555b57] MIPS: Skip odd double FP registers when copying FP32 sigcontext
> > > git bisect bad 1793cdaa84ed5c4025a36793f350b07b49555b57
> > > # good: [8a6bb0ab74eaca5f2a4e60f94df2ea5b08cdfd63] MIPS: Simplify EVA FP context handling code
> > > git bisect good 8a6bb0ab74eaca5f2a4e60f94df2ea5b08cdfd63
> > > # good: [6f47ebd751531249fe0e2b4d3afdfcbf9f66dbd8] MIPS: Use struct mips_abi offsets to save FP context
> > > git bisect good 6f47ebd751531249fe0e2b4d3afdfcbf9f66dbd8
> > > # bad: [fa3156ca734cb65f23df0f844433e75ea1da37f3] MIPS: Move FP usage checks into protected_{save, restore}_fp_context
> > > git bisect bad fa3156ca734cb65f23df0f844433e75ea1da37f3
> > > # first bad commit: [fa3156ca734cb65f23df0f844433e75ea1da37f3] MIPS: Move FP usage checks into protected_{save, restore}_fp_context

Re: Crash in -next due to 'MIPS: Move FP usage checks into protected_{save, restore}_fp_context'

[Paul Burton]

On Mon, Jul 27, 2015 at 10:46:22AM -0700, Guenter Roeck wrote:
> On Mon, Jul 27, 2015 at 10:21:42AM -0700, Paul Burton wrote:
> > On Mon, Jul 27, 2015 at 08:06:52AM -0700, Guenter Roeck wrote:
> > > On Wed, Jul 15, 2015 at 09:09:18AM -0700, Guenter Roeck wrote:
> > > > Hi,
> > > > 
> > > > my qemu test for mipsel crashes with next-20150715 as follows.
> > > > 
> > > ping ... problem is still seen as of next-20150727.
> > 
> > Hi Guenter,
> > 
> > Apologies for the delay. Could you share your affected kernel
> > configuration & which userland you're running?
> > 
> > I've just tested with a malta_defconfig kernel & a buildroot based
> > initramfs without problems, and things are also fine on my physical
> > MIPSr6 setups. If you have any directions with which I can reproduce
> > this problem that would be great.
> > 
> This is with qemu in little endian mode. Big endian works fine.

Yup, I was using little endian in both cases. malta_defconfig is little
endian - sadly use of the el suffix is pretty inconsistent...

> The configuration, the script to build and run the kernel, 
> and the root file system used are are available at
> https://github.com/groeck/linux-build-test, in directory
> rootfs/mipsel/. The log for the latest build failure is in
> http://server.roeck-us.net:8010/builders/qemu-mipsel-next/builds/194/steps/qemubuildcommand/logs/stdio.

Thanks for the pointers, I'm able to reproduce it using your config and
initramfs, and I'll dig into what's going on here.

Paul

Re: Crash in -next due to 'MIPS: Move FP usage checks into protected_{save, restore}_fp_context'

[Guenter Roeck]

On Mon, Jul 27, 2015 at 11:04:42AM -0700, Paul Burton wrote:
> On Mon, Jul 27, 2015 at 10:46:22AM -0700, Guenter Roeck wrote:
> > On Mon, Jul 27, 2015 at 10:21:42AM -0700, Paul Burton wrote:
> > > On Mon, Jul 27, 2015 at 08:06:52AM -0700, Guenter Roeck wrote:
> > > > On Wed, Jul 15, 2015 at 09:09:18AM -0700, Guenter Roeck wrote:
> > > > > Hi,
> > > > > 
> > > > > my qemu test for mipsel crashes with next-20150715 as follows.
> > > > > 
> > > > ping ... problem is still seen as of next-20150727.
> > > 
> > > Hi Guenter,
> > > 
> > > Apologies for the delay. Could you share your affected kernel
> > > configuration & which userland you're running?
> > > 
> > > I've just tested with a malta_defconfig kernel & a buildroot based
> > > initramfs without problems, and things are also fine on my physical
> > > MIPSr6 setups. If you have any directions with which I can reproduce
> > > this problem that would be great.
> > > 
> > This is with qemu in little endian mode. Big endian works fine.
> 
> Yup, I was using little endian in both cases. malta_defconfig is little
> endian - sadly use of the el suffix is pretty inconsistent...
> 
Interesting.

> > The configuration, the script to build and run the kernel, 
> > and the root file system used are are available at
> > https://github.com/groeck/linux-build-test, in directory
> > rootfs/mipsel/. The log for the latest build failure is in
> > http://server.roeck-us.net:8010/builders/qemu-mipsel-next/builds/194/steps/qemubuildcommand/logs/stdio.
> 
> Thanks for the pointers, I'm able to reproduce it using your config and
> initramfs, and I'll dig into what's going on here.
> 
Let me know what you find. Maybe something is wrong with my configuration
or initramfs, but it is odd that I didn't see the problem earlier.

Unfortunately I don't recall where I got the configuration from.
Guess I should keep notes :-(.

Thanks,
Guenter

Re: Crash in -next due to 'MIPS: Move FP usage checks into protected_{save, restore}_fp_context'

[Guenter Roeck]

On Mon, Jul 27, 2015 at 11:04:42AM -0700, Paul Burton wrote:
> On Mon, Jul 27, 2015 at 10:46:22AM -0700, Guenter Roeck wrote:
> > On Mon, Jul 27, 2015 at 10:21:42AM -0700, Paul Burton wrote:
> > > On Mon, Jul 27, 2015 at 08:06:52AM -0700, Guenter Roeck wrote:
> > > > On Wed, Jul 15, 2015 at 09:09:18AM -0700, Guenter Roeck wrote:
> > > > > Hi,
> > > > 
> > > > > my qemu test for mipsel crashes with next-20150715 as follows.
> > > > > 
> > > > ping ... problem is still seen as of next-20150727.
> > > 
> > > Hi Guenter,
> > > 
> > > Apologies for the delay. Could you share your affected kernel
> > > configuration & which userland you're running?
> > > 
> > > I've just tested with a malta_defconfig kernel & a buildroot based
> > > initramfs without problems, and things are also fine on my physical
> > > MIPSr6 setups. If you have any directions with which I can reproduce
> > > this problem that would be great.
> > > 
> > This is with qemu in little endian mode. Big endian works fine.
> 
> Yup, I was using little endian in both cases. malta_defconfig is little
> endian - sadly use of the el suffix is pretty inconsistent...
> 

Hi Paul,

some more data:

I tried with mipsel64, using malta_defconfig from 4.2-rc4 as starting point.
Same failure. All releases from 3.2 up to 4.2-rc4 pass the test, linux-next
as of today fails.

Here is the log:

http://server.roeck-us.net:8010/builders/qemu-mipsel64-next/builds/0/steps/qemubuildcommand/logs/stdio

I pushed the initramfs, configuration, and test script into rootfs/mipsel64
of https://github.com/groeck/linux-build-test.

Guenter

Re: Crash in -next due to 'MIPS: Move FP usage checks into protected_{save, restore}_fp_context'

[Paul Burton]

On Mon, Jul 27, 2015 at 12:44:01PM -0700, Guenter Roeck wrote:
> On Mon, Jul 27, 2015 at 11:04:42AM -0700, Paul Burton wrote:
> > On Mon, Jul 27, 2015 at 10:46:22AM -0700, Guenter Roeck wrote:
> > > On Mon, Jul 27, 2015 at 10:21:42AM -0700, Paul Burton wrote:
> > > > On Mon, Jul 27, 2015 at 08:06:52AM -0700, Guenter Roeck wrote:
> > > > > On Wed, Jul 15, 2015 at 09:09:18AM -0700, Guenter Roeck wrote:
> > > > > > Hi,
> > > > > 
> > > > > > my qemu test for mipsel crashes with next-20150715 as follows.
> > > > > > 
> > > > > ping ... problem is still seen as of next-20150727.
> > > > 
> > > > Hi Guenter,
> > > > 
> > > > Apologies for the delay. Could you share your affected kernel
> > > > configuration & which userland you're running?
> > > > 
> > > > I've just tested with a malta_defconfig kernel & a buildroot based
> > > > initramfs without problems, and things are also fine on my physical
> > > > MIPSr6 setups. If you have any directions with which I can reproduce
> > > > this problem that would be great.
> > > > 
> > > This is with qemu in little endian mode. Big endian works fine.
> > 
> > Yup, I was using little endian in both cases. malta_defconfig is little
> > endian - sadly use of the el suffix is pretty inconsistent...
> > 
> 
> Hi Paul,
> 
> some more data:
> 
> I tried with mipsel64, using malta_defconfig from 4.2-rc4 as starting point.
> Same failure. All releases from 3.2 up to 4.2-rc4 pass the test, linux-next
> as of today fails.
> 
> Here is the log:
> 
> http://server.roeck-us.net:8010/builders/qemu-mipsel64-next/builds/0/steps/qemubuildcommand/logs/stdio
> 
> I pushed the initramfs, configuration, and test script into rootfs/mipsel64
> of https://github.com/groeck/linux-build-test.

Hi Guenter,

I'm currently mailing out v2 of the series which should fix your
problem. It was an issue where the kernel would check the FP context for
whether a SIGFPE should be generated even in cases where FP had not been
used by userland, and thus had not been initialised. My userland is
hard float & thus makes use of the FPU early whilst I believe yours is
soft float, which explains the difference in behaviour.

I think the endian difference probably boils down to what garbage the
initial FP context contained.

Ralf: can you update the patches in -next please?

Thanks,
    Paul

Re: Crash in -next due to 'MIPS: Move FP usage checks into protected_{save, restore}_fp_context'

[Guenter Roeck]

Hi Paul,

On Mon, Jul 27, 2015 at 01:02:14PM -0700, Paul Burton wrote:
> 
> Hi Guenter,
> 
> I'm currently mailing out v2 of the series which should fix your
> problem. It was an issue where the kernel would check the FP context for
> whether a SIGFPE should be generated even in cases where FP had not been
> used by userland, and thus had not been initialised. My userland is
> hard float & thus makes use of the FPU early whilst I believe yours is
> soft float, which explains the difference in behaviour.
> 
> I think the endian difference probably boils down to what garbage the
> initial FP context contained.
> 
Thanks a lot for the fix!

Guenter

Re: Crash in -next due to 'MIPS: Move FP usage checks into protected_{save, restore}_fp_context'

[Ralf Baechle]

On Mon, Jul 27, 2015 at 01:02:14PM -0700, Paul Burton wrote:

> Ralf: can you update the patches in -next please?

Done.  Will push in a few minutes to upstream-sfr; should make it to
-next by tomorrow.

But <rant> could you next time please send a patchset based on something
halfway recent?  Five patches had merge conflicts, one is already upstream.
</rant>.

  Ralf