diff options
| author | Paul Walmsley <paul@pwsan.com> | 2012-10-23 20:32:59 +0100 |
|---|---|---|
| committer | Ben Hutchings <ben@decadent.org.uk> | 2013-01-03 03:32:49 +0000 |
| commit | 6df81a71856743655368b3e877c9cc6b198719d1 (patch) | |
| tree | f55841f240afb04b261dc0740ad2623d85e53a01 /arch | |
| parent | 281f409aecf98336de9b15d7f931c438bfdc545f (diff) | |
ARM: 7566/1: vfp: fix save and restore when running on pre-VFPv3 and CONFIG_VFPv3 set
commit 39141ddfb63a664f26d3f42f64ee386e879b492c upstream.
After commit 846a136881b8f73c1f74250bf6acfaa309cab1f2 ("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 5aaf254409f8d58229107b59507a8235b715a960 ("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>
[bwh: Backported to 3.2: adjust filename]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/arm/include/asm/hwcap.h | 3 | ||||
| -rw-r--r-- | arch/arm/include/asm/vfpmacros.h | 12 | ||||
| -rw-r--r-- | arch/arm/vfp/vfpmodule.c | 9 |
3 files changed, 14 insertions, 10 deletions
diff --git a/arch/arm/include/asm/hwcap.h b/arch/arm/include/asm/hwcap.h index c93a22a8b92..3a925fb6334 100644 --- a/arch/arm/include/asm/hwcap.h +++ b/arch/arm/include/asm/hwcap.h @@ -18,11 +18,12 @@ #define HWCAP_THUMBEE (1 << 11) #define HWCAP_NEON (1 << 12) #define HWCAP_VFPv3 (1 << 13) -#define HWCAP_VFPv3D16 (1 << 14) +#define HWCAP_VFPv3D16 (1 << 14) /* also set for VFPv4-D16 */ #define HWCAP_TLS (1 << 15) #define HWCAP_VFPv4 (1 << 16) #define HWCAP_IDIVA (1 << 17) #define HWCAP_IDIVT (1 << 18) +#define HWCAP_VFPD32 (1 << 19) /* set if VFP has 32 regs (not 16) */ #define HWCAP_IDIV (HWCAP_IDIVA | HWCAP_IDIVT) #if defined(__KERNEL__) && !defined(__ASSEMBLY__) diff --git a/arch/arm/include/asm/vfpmacros.h b/arch/arm/include/asm/vfpmacros.h index bf5304797c7..c49c8f778b5 100644 --- a/arch/arm/include/asm/vfpmacros.h +++ b/arch/arm/include/asm/vfpmacros.h @@ -27,9 +27,9 @@ #if __LINUX_ARM_ARCH__ <= 6 ldr \tmp, =elf_hwcap @ may not have MVFR regs ldr \tmp, [\tmp, #0] - tst \tmp, #HWCAP_VFPv3D16 - ldceql p11, cr0, [\base],#32*4 @ FLDMIAD \base!, {d16-d31} - addne \base, \base, #32*4 @ step over unused register space + tst \tmp, #HWCAP_VFPD32 + ldcnel p11, cr0, [\base],#32*4 @ FLDMIAD \base!, {d16-d31} + addeq \base, \base, #32*4 @ step over unused register space #else VFPFMRX \tmp, MVFR0 @ Media and VFP Feature Register 0 and \tmp, \tmp, #MVFR0_A_SIMD_MASK @ A_SIMD field @@ -51,9 +51,9 @@ #if __LINUX_ARM_ARCH__ <= 6 ldr \tmp, =elf_hwcap @ may not have MVFR regs ldr \tmp, [\tmp, #0] - tst \tmp, #HWCAP_VFPv3D16 - stceql p11, cr0, [\base],#32*4 @ FSTMIAD \base!, {d16-d31} - addne \base, \base, #32*4 @ step over unused register space + tst \tmp, #HWCAP_VFPD32 + stcnel p11, cr0, [\base],#32*4 @ FSTMIAD \base!, {d16-d31} + addeq \base, \base, #32*4 @ step over unused register space #else VFPFMRX \tmp, MVFR0 @ Media and VFP Feature Register 0 and \tmp, \tmp, #MVFR0_A_SIMD_MASK @ A_SIMD field diff --git a/arch/arm/vfp/vfpmodule.c b/arch/arm/vfp/vfpmodule.c index f0702f384f4..7c815b2f0c5 100644 --- a/arch/arm/vfp/vfpmodule.c +++ b/arch/arm/vfp/vfpmodule.c @@ -610,11 +610,14 @@ static int __init vfp_init(void) elf_hwcap |= HWCAP_VFPv3; /* - * Check for VFPv3 D16. CPUs in this configuration - * only have 16 x 64bit registers. + * Check for VFPv3 D16 and VFPv4 D16. CPUs in + * this configuration only have 16 x 64bit + * registers. */ if (((fmrx(MVFR0) & MVFR0_A_SIMD_MASK)) == 1) - elf_hwcap |= HWCAP_VFPv3D16; + elf_hwcap |= HWCAP_VFPv3D16; /* also v4-D16 */ + else + elf_hwcap |= HWCAP_VFPD32; } #endif /* |