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33f082614c
This patch defines an extra_context signal frame record that can be used to describe an expanded signal frame, and modifies the context block allocator and signal frame setup and parsing code to create, populate, parse and decode this block as necessary. To avoid abuse by userspace, parse_user_sigframe() attempts to ensure that: * no more than one extra_context is accepted; * the extra context data is a sensible size, and properly placed and aligned. The extra_context data is required to start at the first 16-byte aligned address immediately after the dummy terminator record following extra_context in rt_sigframe.__reserved[] (as ensured during signal delivery). This serves as a sanity-check that the signal frame has not been moved or copied without taking the extra data into account. Signed-off-by: Dave Martin <Dave.Martin@arm.com> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> [will: add __force annotation when casting extra_datap to __user pointer] Signed-off-by: Will Deacon <will.deacon@arm.com>
120 lines
3.6 KiB
C
120 lines
3.6 KiB
C
/*
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* Copyright (C) 2012 ARM Ltd.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#ifndef _UAPI__ASM_SIGCONTEXT_H
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#define _UAPI__ASM_SIGCONTEXT_H
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#include <linux/types.h>
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/*
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* Signal context structure - contains all info to do with the state
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* before the signal handler was invoked.
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*/
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struct sigcontext {
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__u64 fault_address;
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/* AArch64 registers */
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__u64 regs[31];
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__u64 sp;
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__u64 pc;
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__u64 pstate;
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/* 4K reserved for FP/SIMD state and future expansion */
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__u8 __reserved[4096] __attribute__((__aligned__(16)));
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};
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/*
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* Allocation of __reserved[]:
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* (Note: records do not necessarily occur in the order shown here.)
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*
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* size description
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*
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* 0x210 fpsimd_context
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* 0x10 esr_context
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* 0x20 extra_context (optional)
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* 0x10 terminator (null _aarch64_ctx)
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*
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* 0xdb0 (reserved for future allocation)
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*
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* New records that can exceed this space need to be opt-in for userspace, so
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* that an expanded signal frame is not generated unexpectedly. The mechanism
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* for opting in will depend on the extension that generates each new record.
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* The above table documents the maximum set and sizes of records than can be
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* generated when userspace does not opt in for any such extension.
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*/
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/*
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* Header to be used at the beginning of structures extending the user
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* context. Such structures must be placed after the rt_sigframe on the stack
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* and be 16-byte aligned. The last structure must be a dummy one with the
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* magic and size set to 0.
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*/
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struct _aarch64_ctx {
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__u32 magic;
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__u32 size;
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};
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#define FPSIMD_MAGIC 0x46508001
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struct fpsimd_context {
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struct _aarch64_ctx head;
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__u32 fpsr;
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__u32 fpcr;
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__uint128_t vregs[32];
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};
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/* ESR_EL1 context */
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#define ESR_MAGIC 0x45535201
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struct esr_context {
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struct _aarch64_ctx head;
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__u64 esr;
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};
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/*
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* extra_context: describes extra space in the signal frame for
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* additional structures that don't fit in sigcontext.__reserved[].
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*
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* Note:
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*
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* 1) fpsimd_context, esr_context and extra_context must be placed in
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* sigcontext.__reserved[] if present. They cannot be placed in the
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* extra space. Any other record can be placed either in the extra
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* space or in sigcontext.__reserved[], unless otherwise specified in
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* this file.
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*
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* 2) There must not be more than one extra_context.
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*
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* 3) If extra_context is present, it must be followed immediately in
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* sigcontext.__reserved[] by the terminating null _aarch64_ctx.
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*
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* 4) The extra space to which datap points must start at the first
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* 16-byte aligned address immediately after the terminating null
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* _aarch64_ctx that follows the extra_context structure in
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* __reserved[]. The extra space may overrun the end of __reserved[],
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* as indicated by a sufficiently large value for the size field.
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*
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* 5) The extra space must itself be terminated with a null
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* _aarch64_ctx.
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*/
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#define EXTRA_MAGIC 0x45585401
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struct extra_context {
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struct _aarch64_ctx head;
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__u64 datap; /* 16-byte aligned pointer to extra space cast to __u64 */
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__u32 size; /* size in bytes of the extra space */
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__u32 __reserved[3];
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};
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#endif /* _UAPI__ASM_SIGCONTEXT_H */
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