linux/arch/arm/include/uapi/asm
Paul Walmsley 39141ddfb6 ARM: 7566/1: vfp: fix save and restore when running on pre-VFPv3 and CONFIG_VFPv3 set
After commit 846a136881 ("ARM: vfp: fix
saving d16-d31 vfp registers on v6+ kernels"), the OMAP 2430SDP board
started crashing during boot with omap2plus_defconfig:

[    3.875122] mmcblk0: mmc0:e624 SD04G 3.69 GiB
[    3.915954]  mmcblk0: p1
[    4.086639] Internal error: Oops - undefined instruction: 0 [#1] SMP ARM
[    4.093719] Modules linked in:
[    4.096954] CPU: 0    Not tainted  (3.6.0-02232-g759e00b #570)
[    4.103149] PC is at vfp_reload_hw+0x1c/0x44
[    4.107666] LR is at __und_usr_fault_32+0x0/0x8

It turns out that the context save/restore fix unmasked a latent bug
in commit 5aaf254409 ("ARM: 6203/1: Make
VFPv3 usable on ARMv6").  When CONFIG_VFPv3 is set, but the kernel is
booted on a pre-VFPv3 core, the code attempts to save and restore the
d16-d31 VFP registers.  These are only present on non-D16 VFPv3+, so
this results in an undefined instruction exception.  The code didn't
crash before commit 846a136 because the save and restore code was
only touching d0-d15, present on all VFP.

Fix by implementing a request from Russell King to add a new HWCAP
flag that affirmatively indicates the presence of the d16-d31
registers:

   http://marc.info/?l=linux-arm-kernel&m=135013547905283&w=2

and some feedback from Måns to clarify the name of the HWCAP flag.

Signed-off-by: Paul Walmsley <paul@pwsan.com>
Cc: Tony Lindgren <tony@atomide.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Dave Martin <dave.martin@linaro.org>
Cc: Måns Rullgård <mans.rullgard@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2012-10-29 10:04:05 +00:00
..
a.out.h UAPI: (Scripted) Disintegrate arch/arm/include/asm 2012-10-12 13:05:52 +01:00
byteorder.h UAPI: (Scripted) Disintegrate arch/arm/include/asm 2012-10-12 13:05:52 +01:00
fcntl.h UAPI: (Scripted) Disintegrate arch/arm/include/asm 2012-10-12 13:05:52 +01:00
hwcap.h ARM: 7566/1: vfp: fix save and restore when running on pre-VFPv3 and CONFIG_VFPv3 set 2012-10-29 10:04:05 +00:00
ioctls.h UAPI: (Scripted) Disintegrate arch/arm/include/asm 2012-10-12 13:05:52 +01:00
Kbuild UAPI: (Scripted) Disintegrate arch/arm/include/asm 2012-10-12 13:05:52 +01:00
kvm_para.h UAPI: (Scripted) Disintegrate arch/arm/include/asm 2012-10-12 13:05:52 +01:00
mman.h UAPI: (Scripted) Disintegrate arch/arm/include/asm 2012-10-12 13:05:52 +01:00
posix_types.h UAPI: (Scripted) Disintegrate arch/arm/include/asm 2012-10-12 13:05:52 +01:00
ptrace.h UAPI: (Scripted) Disintegrate arch/arm/include/asm 2012-10-12 13:05:52 +01:00
setup.h UAPI: (Scripted) Disintegrate arch/arm/include/asm 2012-10-12 13:05:52 +01:00
sigcontext.h UAPI: (Scripted) Disintegrate arch/arm/include/asm 2012-10-12 13:05:52 +01:00
signal.h UAPI: (Scripted) Disintegrate arch/arm/include/asm 2012-10-12 13:05:52 +01:00
stat.h UAPI: (Scripted) Disintegrate arch/arm/include/asm 2012-10-12 13:05:52 +01:00
statfs.h UAPI: (Scripted) Disintegrate arch/arm/include/asm 2012-10-12 13:05:52 +01:00
swab.h UAPI: (Scripted) Disintegrate arch/arm/include/asm 2012-10-12 13:05:52 +01:00
unistd.h UAPI: (Scripted) Disintegrate arch/arm/include/asm 2012-10-12 13:05:52 +01:00