[LLDB] Add Linux SVE Ptrace macros.

[kristof.beyls]

Summary

@labath this SVE header from ARM is being directly contributed by an ARM employee with all relevant license authority available to him.

LGTM?

lldb/source/Plugins/Process/Linux/LinuxPTraceDefines_arm64sve.h

+//===-- LinuxPTraceDefines_arm64sve.h ------------------------- -*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef lldb_LinuxPTraceDefines_arm64sve_h
+#define lldb_LinuxPTraceDefines_arm64sve_h
+
+#define SVE_MAGIC 0x53564501
+
+struct sve_context {
+  struct _aarch64_ctx head;
+  __u16 vl;
+  __u16 __reserved[3];
+};
+
+/*
+ * The SVE architecture leaves space for future expansion of the
+ * vector length beyond its initial architectural limit of 2048 bits
+ * (16 quadwords).
+ *
+ * See linux/Documentation/arm64/sve.txt for a description of the VL/VQ
+ * terminology.
+ */
+#define SVE_VQ_BYTES 16 /* number of bytes per quadword */
+
+#define SVE_VQ_MIN 1
+#define SVE_VQ_MAX 512
+
+#define SVE_VL_MIN (SVE_VQ_MIN * SVE_VQ_BYTES)
+#define SVE_VL_MAX (SVE_VQ_MAX * SVE_VQ_BYTES)
+
+#define SVE_NUM_ZREGS 32
+#define SVE_NUM_PREGS 16
+
+#define sve_vl_valid(vl)                                                       \
+  ((vl) % SVE_VQ_BYTES == 0 && (vl) >= SVE_VL_MIN && (vl) <= SVE_VL_MAX)
+#define sve_vq_from_vl(vl) ((vl) / SVE_VQ_BYTES)
+#define sve_vl_from_vq(vq) ((vq)*SVE_VQ_BYTES)
+
+/*
+ * If the SVE registers are currently live for the thread at signal delivery,
+ * sve_context.head.size >=
+ *  SVE_SIG_CONTEXT_SIZE(sve_vq_from_vl(sve_context.vl))
+ * and the register data may be accessed using the SVE_SIG_*() macros.
+ *
+ * If sve_context.head.size <
+ *  SVE_SIG_CONTEXT_SIZE(sve_vq_from_vl(sve_context.vl)),
+ * the SVE registers were not live for the thread and no register data
+ * is included: in this case, the SVE_SIG_*() macros should not be
+ * used except for this check.
+ *
+ * The same convention applies when returning from a signal: a caller
+ * will need to remove or resize the sve_context block if it wants to
+ * make the SVE registers live when they were previously non-live or
+ * vice-versa.  This may require the the caller to allocate fresh
+ * memory and/or move other context blocks in the signal frame.
+ *
+ * Changing the vector length during signal return is not permitted:
+ * sve_context.vl must equal the thread's current vector length when
+ * doing a sigreturn.
+ *
+ *
+ * Note: for all these macros, the "vq" argument denotes the SVE
+ * vector length in quadwords (i.e., units of 128 bits).
+ *
+ * The correct way to obtain vq is to use sve_vq_from_vl(vl).  The
+ * result is valid if and only if sve_vl_valid(vl) is true.  This is
+ * guaranteed for a struct sve_context written by the kernel.
+ *
+ *
+ * Additional macros describe the contents and layout of the payload.
+ * For each, SVE_SIG_x_OFFSET(args) is the start offset relative to
+ * the start of struct sve_context, and SVE_SIG_x_SIZE(args) is the
+ * size in bytes:
+ *
+ *  x type        description
+ *  - ----        -----------
+ *  REGS          the entire SVE context
+ *
+ *  ZREGS __uint128_t[SVE_NUM_ZREGS][vq]  all Z-registers
+ *  ZREG  __uint128_t[vq]     individual Z-register Zn
+ *
+ *  PREGS uint16_t[SVE_NUM_PREGS][vq] all P-registers
+ *  PREG  uint16_t[vq]      individual P-register Pn
+ *
+ *  FFR uint16_t[vq]      first-fault status register
+ *
+ * Additional data might be appended in the future.
+ */
+
+#define SVE_SIG_ZREG_SIZE(vq) ((__u32)(vq)*SVE_VQ_BYTES)
+#define SVE_SIG_PREG_SIZE(vq) ((__u32)(vq) * (SVE_VQ_BYTES / 8))
+#define SVE_SIG_FFR_SIZE(vq) SVE_SIG_PREG_SIZE(vq)
+
+#define SVE_SIG_REGS_OFFSET                                                    \
+  ((sizeof(struct sve_context) + (SVE_VQ_BYTES - 1)) / SVE_VQ_BYTES *          \
+   SVE_VQ_BYTES)
+
+#define SVE_SIG_ZREGS_OFFSET SVE_SIG_REGS_OFFSET
+#define SVE_SIG_ZREG_OFFSET(vq, n)                                             \
+  (SVE_SIG_ZREGS_OFFSET + SVE_SIG_ZREG_SIZE(vq) * (n))
+#define SVE_SIG_ZREGS_SIZE(vq)                                                 \
+  (SVE_SIG_ZREG_OFFSET(vq, SVE_NUM_ZREGS) - SVE_SIG_ZREGS_OFFSET)
+
+#define SVE_SIG_PREGS_OFFSET(vq) (SVE_SIG_ZREGS_OFFSET + SVE_SIG_ZREGS_SIZE(vq))
+#define SVE_SIG_PREG_OFFSET(vq, n)                                             \
+  (SVE_SIG_PREGS_OFFSET(vq) + SVE_SIG_PREG_SIZE(vq) * (n))
+#define SVE_SIG_PREGS_SIZE(vq)                                                 \
+  (SVE_SIG_PREG_OFFSET(vq, SVE_NUM_PREGS) - SVE_SIG_PREGS_OFFSET(vq))
+
+#define SVE_SIG_FFR_OFFSET(vq)                                                 \
+  (SVE_SIG_PREGS_OFFSET(vq) + SVE_SIG_PREGS_SIZE(vq))
+
+#define SVE_SIG_REGS_SIZE(vq)                                                  \
+  (SVE_SIG_FFR_OFFSET(vq) + SVE_SIG_FFR_SIZE(vq) - SVE_SIG_REGS_OFFSET)
+
+#define SVE_SIG_CONTEXT_SIZE(vq) (SVE_SIG_REGS_OFFSET + SVE_SIG_REGS_SIZE(vq))
+
+/* SVE/FP/SIMD state (NT_ARM_SVE) */
+
+struct user_sve_header {
+  __u32 size;     /* total meaningful regset content in bytes */
+  __u32 max_size; /* maxmium possible size for this thread */
+  __u16 vl;       /* current vector length */
+  __u16 max_vl;   /* maximum possible vector length */
+  __u16 flags;
+  __u16 __reserved;
+};
+
+/* Definitions for user_sve_header.flags: */
+#define SVE_PT_REGS_MASK (1 << 0)
+
+#define SVE_PT_REGS_FPSIMD 0
+#define SVE_PT_REGS_SVE SVE_PT_REGS_MASK
+
+/*
+ * Common SVE_PT_* flags:
+ * These must be kept in sync with prctl interface in <linux/ptrace.h>
+ */
+#define SVE_PT_VL_INHERIT (PR_SVE_VL_INHERIT >> 16)
+#define SVE_PT_VL_ONEXEC (PR_SVE_SET_VL_ONEXEC >> 16)
+
+/*
+ * The remainder of the SVE state follows struct user_sve_header.  The
+ * total size of the SVE state (including header) depends on the
+ * metadata in the header:  SVE_PT_SIZE(vq, flags) gives the total size
+ * of the state in bytes, including the header.
+ *
+ * Refer to <asm/sigcontext.h> for details of how to pass the correct
+ * "vq" argument to these macros.
+ */
+
+/* Offset from the start of struct user_sve_header to the register data */
+#define SVE_PT_REGS_OFFSET                                                     \
+  ((sizeof(struct sve_context) + (SVE_VQ_BYTES - 1)) / SVE_VQ_BYTES *          \
+   SVE_VQ_BYTES)
+
+/*
+ * The register data content and layout depends on the value of the
+ * flags field.
+ */
+
+/*
+ * (flags & SVE_PT_REGS_MASK) == SVE_PT_REGS_FPSIMD case:
+ *
+ * The payload starts at offset SVE_PT_FPSIMD_OFFSET, and is of type
+ * struct user_fpsimd_state.  Additional data might be appended in the
+ * future: use SVE_PT_FPSIMD_SIZE(vq, flags) to compute the total size.
+ * SVE_PT_FPSIMD_SIZE(vq, flags) will never be less than
+ * sizeof(struct user_fpsimd_state).
+ */
+
+#define SVE_PT_FPSIMD_OFFSET SVE_PT_REGS_OFFSET
+
+#define SVE_PT_FPSIMD_SIZE(vq, flags) (sizeof(struct user_fpsimd_state))
+
+/*
+ * (flags & SVE_PT_REGS_MASK) == SVE_PT_REGS_SVE case:
+ *
+ * The payload starts at offset SVE_PT_SVE_OFFSET, and is of size
+ * SVE_PT_SVE_SIZE(vq, flags).
+ *
+ * Additional macros describe the contents and layout of the payload.
+ * For each, SVE_PT_SVE_x_OFFSET(args) is the start offset relative to
+ * the start of struct user_sve_header, and SVE_PT_SVE_x_SIZE(args) is
+ * the size in bytes:
+ *
+ *  x type        description
+ *  - ----        -----------
+ *  ZREGS   \
+ *  ZREG    |
+ *  PREGS   | refer to <asm/sigcontext.h>
+ *  PREG    |
+ *  FFR   /
+ *
+ *  FPSR  uint32_t      FPSR
+ *  FPCR  uint32_t      FPCR
+ *
+ * Additional data might be appended in the future.
+ */
+
+#define SVE_PT_SVE_ZREG_SIZE(vq) SVE_SIG_ZREG_SIZE(vq)
+#define SVE_PT_SVE_PREG_SIZE(vq) SVE_SIG_PREG_SIZE(vq)
+#define SVE_PT_SVE_FFR_SIZE(vq) SVE_SIG_FFR_SIZE(vq)
+#define SVE_PT_SVE_FPSR_SIZE sizeof(__u32)
+#define SVE_PT_SVE_FPCR_SIZE sizeof(__u32)
+
+#define __SVE_SIG_TO_PT(offset)                                                \
+  ((offset)-SVE_SIG_REGS_OFFSET + SVE_PT_REGS_OFFSET)
+
+#define SVE_PT_SVE_OFFSET SVE_PT_REGS_OFFSET
+
+#define SVE_PT_SVE_ZREGS_OFFSET __SVE_SIG_TO_PT(SVE_SIG_ZREGS_OFFSET)
+#define SVE_PT_SVE_ZREG_OFFSET(vq, n)                                          \
+  __SVE_SIG_TO_PT(SVE_SIG_ZREG_OFFSET(vq, n))
+#define SVE_PT_SVE_ZREGS_SIZE(vq)                                              \
+  (SVE_PT_SVE_ZREG_OFFSET(vq, SVE_NUM_ZREGS) - SVE_PT_SVE_ZREGS_OFFSET)
+
+#define SVE_PT_SVE_PREGS_OFFSET(vq) __SVE_SIG_TO_PT(SVE_SIG_PREGS_OFFSET(vq))
+#define SVE_PT_SVE_PREG_OFFSET(vq, n)                                          \
+  __SVE_SIG_TO_PT(SVE_SIG_PREG_OFFSET(vq, n))
+#define SVE_PT_SVE_PREGS_SIZE(vq)                                              \
+  (SVE_PT_SVE_PREG_OFFSET(vq, SVE_NUM_PREGS) - SVE_PT_SVE_PREGS_OFFSET(vq))
+
+#define SVE_PT_SVE_FFR_OFFSET(vq) __SVE_SIG_TO_PT(SVE_SIG_FFR_OFFSET(vq))
+
+#define SVE_PT_SVE_FPSR_OFFSET(vq)                                             \
+  ((SVE_PT_SVE_FFR_OFFSET(vq) + SVE_PT_SVE_FFR_SIZE(vq) +                      \
+    (SVE_VQ_BYTES - 1)) /                                                      \
+   SVE_VQ_BYTES * SVE_VQ_BYTES)
+#define SVE_PT_SVE_FPCR_OFFSET(vq)                                             \
+  (SVE_PT_SVE_FPSR_OFFSET(vq) + SVE_PT_SVE_FPSR_SIZE)
+
+/*
+ * Any future extension appended after FPCR must be aligned to the next
+ * 128-bit boundary.
+ */
+
+#define SVE_PT_SVE_SIZE(vq, flags)                                             \
+  ((SVE_PT_SVE_FPCR_OFFSET(vq) + SVE_PT_SVE_FPCR_SIZE - SVE_PT_SVE_OFFSET +    \
+    (SVE_VQ_BYTES - 1)) /                                                      \
+   SVE_VQ_BYTES * SVE_VQ_BYTES)
+
+#define SVE_PT_SIZE(vq, flags)                                                 \
+  (((flags)&SVE_PT_REGS_MASK) == SVE_PT_REGS_SVE                               \
+       ? SVE_PT_SVE_OFFSET + SVE_PT_SVE_SIZE(vq, flags)                        \
+       : SVE_PT_FPSIMD_OFFSET + SVE_PT_FPSIMD_SIZE(vq, flags))
+
+#endif