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After commit846a136881("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 commit5aaf254409("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 commit846a136because 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>
66 lines
2.1 KiB
C
66 lines
2.1 KiB
C
/*
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* arch/arm/include/asm/vfpmacros.h
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*
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* Assembler-only file containing VFP macros and register definitions.
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*/
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#include <asm/hwcap.h>
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#include <asm/vfp.h>
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@ Macros to allow building with old toolkits (with no VFP support)
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.macro VFPFMRX, rd, sysreg, cond
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MRC\cond p10, 7, \rd, \sysreg, cr0, 0 @ FMRX \rd, \sysreg
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.endm
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.macro VFPFMXR, sysreg, rd, cond
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MCR\cond p10, 7, \rd, \sysreg, cr0, 0 @ FMXR \sysreg, \rd
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.endm
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@ read all the working registers back into the VFP
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.macro VFPFLDMIA, base, tmp
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#if __LINUX_ARM_ARCH__ < 6
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LDC p11, cr0, [\base],#33*4 @ FLDMIAX \base!, {d0-d15}
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#else
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LDC p11, cr0, [\base],#32*4 @ FLDMIAD \base!, {d0-d15}
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#endif
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#ifdef CONFIG_VFPv3
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#if __LINUX_ARM_ARCH__ <= 6
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ldr \tmp, =elf_hwcap @ may not have MVFR regs
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ldr \tmp, [\tmp, #0]
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tst \tmp, #HWCAP_VFPD32
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ldcnel p11, cr0, [\base],#32*4 @ FLDMIAD \base!, {d16-d31}
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addeq \base, \base, #32*4 @ step over unused register space
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#else
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VFPFMRX \tmp, MVFR0 @ Media and VFP Feature Register 0
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and \tmp, \tmp, #MVFR0_A_SIMD_MASK @ A_SIMD field
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cmp \tmp, #2 @ 32 x 64bit registers?
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ldceql p11, cr0, [\base],#32*4 @ FLDMIAD \base!, {d16-d31}
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addne \base, \base, #32*4 @ step over unused register space
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#endif
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#endif
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.endm
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@ write all the working registers out of the VFP
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.macro VFPFSTMIA, base, tmp
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#if __LINUX_ARM_ARCH__ < 6
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STC p11, cr0, [\base],#33*4 @ FSTMIAX \base!, {d0-d15}
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#else
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STC p11, cr0, [\base],#32*4 @ FSTMIAD \base!, {d0-d15}
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#endif
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#ifdef CONFIG_VFPv3
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#if __LINUX_ARM_ARCH__ <= 6
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ldr \tmp, =elf_hwcap @ may not have MVFR regs
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ldr \tmp, [\tmp, #0]
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tst \tmp, #HWCAP_VFPD32
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stcnel p11, cr0, [\base],#32*4 @ FSTMIAD \base!, {d16-d31}
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addeq \base, \base, #32*4 @ step over unused register space
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#else
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VFPFMRX \tmp, MVFR0 @ Media and VFP Feature Register 0
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and \tmp, \tmp, #MVFR0_A_SIMD_MASK @ A_SIMD field
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cmp \tmp, #2 @ 32 x 64bit registers?
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stceql p11, cr0, [\base],#32*4 @ FSTMIAD \base!, {d16-d31}
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addne \base, \base, #32*4 @ step over unused register space
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#endif
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#endif
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.endm
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