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authorPaul Walmsley <paul@pwsan.com>2012-10-23 20:32:59 +0100
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2012-12-17 10:49:02 -0800
commit15a83cc22d40240f1f551b4c2092f7f246bdbfce (patch)
treef20379fa5c82ccd5e14f87164528f310c43e0344 /arch
parent4eb15b7fe7ad2a055f79eb1056a0c2d3317ff6f0 (diff)
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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> Cc: Ben Hutchings <ben@decadent.org.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'arch')
-rw-r--r--arch/arm/include/asm/hwcap.h3
-rw-r--r--arch/arm/include/asm/vfpmacros.h12
-rw-r--r--arch/arm/vfp/vfpmodule.c9
3 files changed, 14 insertions, 10 deletions
diff --git a/arch/arm/include/asm/hwcap.h b/arch/arm/include/asm/hwcap.h
index c1062c3..1e3f30f 100644
--- a/arch/arm/include/asm/hwcap.h
+++ b/arch/arm/include/asm/hwcap.h
@@ -18,8 +18,9 @@
#define HWCAP_THUMBEE 2048
#define HWCAP_NEON 4096
#define HWCAP_VFPv3 8192
-#define HWCAP_VFPv3D16 16384
+#define HWCAP_VFPv3D16 (1 << 14) /* also set for VFPv4-D16 */
#define HWCAP_TLS 32768
+#define HWCAP_VFPD32 (1 << 19) /* set if VFP has 32 regs (not 16) */
#if defined(__KERNEL__) && !defined(__ASSEMBLY__)
/*
diff --git a/arch/arm/include/asm/vfpmacros.h b/arch/arm/include/asm/vfpmacros.h
index bf53047..c49c8f7 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 f25e7ec..ce18802 100644
--- a/arch/arm/vfp/vfpmodule.c
+++ b/arch/arm/vfp/vfpmodule.c
@@ -575,11 +575,14 @@ 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
#ifdef CONFIG_NEON