cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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kgdb.h (3346B)

      1/* SPDX-License-Identifier: GPL-2.0-only */
      2/*
      3 * AArch64 KGDB support
      4 *
      5 * Based on arch/arm/include/kgdb.h
      6 *
      7 * Copyright (C) 2013 Cavium Inc.
      8 * Author: Vijaya Kumar K <vijaya.kumar@caviumnetworks.com>
      9 */
     10
     11#ifndef __ARM_KGDB_H
     12#define __ARM_KGDB_H
     13
     14#include <linux/ptrace.h>
     15#include <asm/debug-monitors.h>
     16
     17#ifndef	__ASSEMBLY__
     18
     19static inline void arch_kgdb_breakpoint(void)
     20{
     21	asm ("brk %0" : : "I" (KGDB_COMPILED_DBG_BRK_IMM));
     22}
     23
     24extern void kgdb_handle_bus_error(void);
     25extern int kgdb_fault_expected;
     26
     27#endif /* !__ASSEMBLY__ */
     28
     29/*
     30 * gdb remote procotol (well most versions of it) expects the following
     31 * register layout.
     32 *
     33 * General purpose regs:
     34 *     r0-r30: 64 bit
     35 *     sp,pc : 64 bit
     36 *     pstate  : 32 bit
     37 *     Total: 33 + 1
     38 * FPU regs:
     39 *     f0-f31: 128 bit
     40 *     fpsr & fpcr: 32 bit
     41 *     Total: 32 + 2
     42 *
     43 * To expand a little on the "most versions of it"... when the gdb remote
     44 * protocol for AArch64 was developed it depended on a statement in the
     45 * Architecture Reference Manual that claimed "SPSR_ELx is a 32-bit register".
     46 * and, as a result, allocated only 32-bits for the PSTATE in the remote
     47 * protocol. In fact this statement is still present in ARM DDI 0487A.i.
     48 *
     49 * Unfortunately "is a 32-bit register" has a very special meaning for
     50 * system registers. It means that "the upper bits, bits[63:32], are
     51 * RES0.". RES0 is heavily used in the ARM architecture documents as a
     52 * way to leave space for future architecture changes. So to translate a
     53 * little for people who don't spend their spare time reading ARM architecture
     54 * manuals, what "is a 32-bit register" actually means in this context is
     55 * "is a 64-bit register but one with no meaning allocated to any of the
     56 * upper 32-bits... *yet*".
     57 *
     58 * Perhaps then we should not be surprised that this has led to some
     59 * confusion. Specifically a patch, influenced by the above translation,
     60 * that extended PSTATE to 64-bit was accepted into gdb-7.7 but the patch
     61 * was reverted in gdb-7.8.1 and all later releases, when this was
     62 * discovered to be an undocumented protocol change.
     63 *
     64 * So... it is *not* wrong for us to only allocate 32-bits to PSTATE
     65 * here even though the kernel itself allocates 64-bits for the same
     66 * state. That is because this bit of code tells the kernel how the gdb
     67 * remote protocol (well most versions of it) describes the register state.
     68 *
     69 * Note that if you are using one of the versions of gdb that supports
     70 * the gdb-7.7 version of the protocol you cannot use kgdb directly
     71 * without providing a custom register description (gdb can load new
     72 * protocol descriptions at runtime).
     73 */
     74
     75#define _GP_REGS		33
     76#define _FP_REGS		32
     77#define _EXTRA_REGS		3
     78/*
     79 * general purpose registers size in bytes.
     80 * pstate is only 4 bytes. subtract 4 bytes
     81 */
     82#define GP_REG_BYTES		(_GP_REGS * 8)
     83#define DBG_MAX_REG_NUM		(_GP_REGS + _FP_REGS + _EXTRA_REGS)
     84
     85/*
     86 * Size of I/O buffer for gdb packet.
     87 * considering to hold all register contents, size is set
     88 */
     89
     90#define BUFMAX			2048
     91
     92/*
     93 * Number of bytes required for gdb_regs buffer.
     94 * _GP_REGS: 8 bytes, _FP_REGS: 16 bytes and _EXTRA_REGS: 4 bytes each
     95 * GDB fails to connect for size beyond this with error
     96 * "'g' packet reply is too long"
     97 */
     98
     99#define NUMREGBYTES	((_GP_REGS * 8) + (_FP_REGS * 16) + \
    100			(_EXTRA_REGS * 4))
    101
    102#endif /* __ASM_KGDB_H */