arch/arm64/include/uapi/asm/sigcontext.h

Source file repositories/reference/linux-study-clean/arch/arm64/include/uapi/asm/sigcontext.h

File Facts

System
Linux kernel
Corpus path
arch/arm64/include/uapi/asm/sigcontext.h
Extension
.h
Size
11386 bytes
Lines
359
Domain
Architecture Layer
Bucket
arch/arm64
Inferred role
Architecture Layer: implementation source
Status
source implementation candidate

Why This File Exists

CPU and platform-specific kernel glue: boot entry, traps, syscall entry, interrupts, page tables, context switch, and low-level barriers.

Dependency Surface

Detected Declarations

Annotated Snippet

struct sigcontext {
	__u64 fault_address;
	/* AArch64 registers */
	__u64 regs[31];
	__u64 sp;
	__u64 pc;
	__u64 pstate;
	/* 4K reserved for FP/SIMD state and future expansion */
	__u8 __reserved[4096] __attribute__((__aligned__(16)));
};

/*
 * Allocation of __reserved[]:
 * (Note: records do not necessarily occur in the order shown here.)
 *
 *	size		description
 *
 *	0x210		fpsimd_context
 *	 0x10		esr_context
 *	0x8a0		sve_context (vl <= 64) (optional)
 *	 0x20		extra_context (optional)
 *	 0x10		terminator (null _aarch64_ctx)
 *
 *	0x510		(reserved for future allocation)
 *
 * New records that can exceed this space need to be opt-in for userspace, so
 * that an expanded signal frame is not generated unexpectedly.  The mechanism
 * for opting in will depend on the extension that generates each new record.
 * The above table documents the maximum set and sizes of records than can be
 * generated when userspace does not opt in for any such extension.
 */

/*
 * Header to be used at the beginning of structures extending the user
 * context. Such structures must be placed after the rt_sigframe on the stack
 * and be 16-byte aligned. The last structure must be a dummy one with the
 * magic and size set to 0.
 *
 * Note that the values allocated for use as magic should be chosen to
 * be meaningful in ASCII to aid manual parsing, ZA doesn't follow this
 * convention due to oversight but it should be observed for future additions.
 */
struct _aarch64_ctx {
	__u32 magic;
	__u32 size;
};

#define FPSIMD_MAGIC	0x46508001

struct fpsimd_context {
	struct _aarch64_ctx head;
	__u32 fpsr;
	__u32 fpcr;
	__uint128_t vregs[32];
};

/*
 * Note: similarly to all other integer fields, each V-register is stored in an
 * endianness-dependent format, with the byte at offset i from the start of the
 * in-memory representation of the register value containing
 *
 *    bits [(7 + 8 * i) : (8 * i)] of the register on little-endian hosts; or
 *    bits [(127 - 8 * i) : (120 - 8 * i)] on big-endian hosts.
 */

/* ESR_EL1 context */
#define ESR_MAGIC	0x45535201

struct esr_context {
	struct _aarch64_ctx head;
	__u64 esr;
};

#define POE_MAGIC	0x504f4530

struct poe_context {
	struct _aarch64_ctx head;
	__u64 por_el0;
};

/*
 * extra_context: describes extra space in the signal frame for
 * additional structures that don't fit in sigcontext.__reserved[].
 *
 * Note:
 *
 * 1) fpsimd_context, esr_context and extra_context must be placed in
 * sigcontext.__reserved[] if present.  They cannot be placed in the
 * extra space.  Any other record can be placed either in the extra
 * space or in sigcontext.__reserved[], unless otherwise specified in

Annotation

Implementation Notes