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ce184a0dee
In kernels with CONFIG_IWMMXT=y running on non-iWMMXt hardware, the signal frame can be left partially uninitialised in such a way that userspace cannot parse uc_regspace[] safely. In particular, this means that the VFP registers cannot be located reliably in the signal frame when a multi_v7_defconfig kernel is run on the majority of platforms. The cause is that the uc_regspace[] is laid out statically based on the kernel config, but the decision of whether to save/restore the iWMMXt registers must be a runtime decision. To minimise breakage of software that may assume a fixed layout, this patch emits a dummy block of the same size as iwmmxt_sigframe, for non-iWMMXt threads. However, the magic and size of this block are now filled in to help parsers skip over it. A new DUMMY_MAGIC is defined for this purpose. It is probably legitimate (if non-portable) for userspace to manufacture its own sigframe for sigreturn, and there is no obvious reason why userspace should be required to insert a DUMMY_MAGIC block when running on non-iWMMXt hardware, when omitting it has worked just fine forever in other configurations. So in this case, sigreturn does not require this block to be present. Reported-by: Edmund Grimley-Evans <Edmund.Grimley-Evans@arm.com> Signed-off-by: Dave Martin <Dave.Martin@arm.com> Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
109 lines
2.9 KiB
C
109 lines
2.9 KiB
C
#ifndef _ASMARM_UCONTEXT_H
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#define _ASMARM_UCONTEXT_H
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#include <asm/fpstate.h>
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/*
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* struct sigcontext only has room for the basic registers, but struct
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* ucontext now has room for all registers which need to be saved and
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* restored. Coprocessor registers are stored in uc_regspace. Each
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* coprocessor's saved state should start with a documented 32-bit magic
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* number, followed by a 32-bit word giving the coproccesor's saved size.
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* uc_regspace may be expanded if necessary, although this takes some
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* coordination with glibc.
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*/
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struct ucontext {
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unsigned long uc_flags;
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struct ucontext *uc_link;
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stack_t uc_stack;
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struct sigcontext uc_mcontext;
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sigset_t uc_sigmask;
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/* Allow for uc_sigmask growth. Glibc uses a 1024-bit sigset_t. */
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int __unused[32 - (sizeof (sigset_t) / sizeof (int))];
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/* Last for extensibility. Eight byte aligned because some
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coprocessors require eight byte alignment. */
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unsigned long uc_regspace[128] __attribute__((__aligned__(8)));
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};
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#ifdef __KERNEL__
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/*
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* Coprocessor save state. The magic values and specific
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* coprocessor's layouts are part of the userspace ABI. Each one of
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* these should be a multiple of eight bytes and aligned to eight
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* bytes, to prevent unpredictable padding in the signal frame.
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*/
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/*
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* Dummy padding block: if this magic is encountered, the block should
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* be skipped using the corresponding size field.
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*/
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#define DUMMY_MAGIC 0xb0d9ed01
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#ifdef CONFIG_CRUNCH
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#define CRUNCH_MAGIC 0x5065cf03
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#define CRUNCH_STORAGE_SIZE (CRUNCH_SIZE + 8)
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struct crunch_sigframe {
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unsigned long magic;
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unsigned long size;
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struct crunch_state storage;
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} __attribute__((__aligned__(8)));
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#endif
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#ifdef CONFIG_IWMMXT
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/* iwmmxt_area is 0x98 bytes long, preceded by 8 bytes of signature */
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#define IWMMXT_MAGIC 0x12ef842a
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#define IWMMXT_STORAGE_SIZE (IWMMXT_SIZE + 8)
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struct iwmmxt_sigframe {
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unsigned long magic;
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unsigned long size;
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struct iwmmxt_struct storage;
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} __attribute__((__aligned__(8)));
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#endif /* CONFIG_IWMMXT */
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#ifdef CONFIG_VFP
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#define VFP_MAGIC 0x56465001
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struct vfp_sigframe
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{
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unsigned long magic;
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unsigned long size;
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struct user_vfp ufp;
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struct user_vfp_exc ufp_exc;
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} __attribute__((__aligned__(8)));
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/*
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* 8 byte for magic and size, 264 byte for ufp, 12 bytes for ufp_exc,
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* 4 bytes padding.
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*/
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#define VFP_STORAGE_SIZE sizeof(struct vfp_sigframe)
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#endif /* CONFIG_VFP */
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/*
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* Auxiliary signal frame. This saves stuff like FP state.
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* The layout of this structure is not part of the user ABI,
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* because the config options aren't. uc_regspace is really
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* one of these.
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*/
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struct aux_sigframe {
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#ifdef CONFIG_CRUNCH
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struct crunch_sigframe crunch;
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#endif
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#ifdef CONFIG_IWMMXT
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struct iwmmxt_sigframe iwmmxt;
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#endif
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#ifdef CONFIG_VFP
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struct vfp_sigframe vfp;
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#endif
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/* Something that isn't a valid magic number for any coprocessor. */
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unsigned long end_magic;
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} __attribute__((__aligned__(8)));
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#endif
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#endif /* !_ASMARM_UCONTEXT_H */
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