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102 lines
3.3 KiB
102 lines
3.3 KiB
/* SPDX-License-Identifier: GPL-2.0-only */ |
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/* |
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* AArch64 KGDB support |
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* |
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* Based on arch/arm/include/kgdb.h |
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* |
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* Copyright (C) 2013 Cavium Inc. |
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* Author: Vijaya Kumar K <[email protected]> |
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*/ |
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#ifndef __ARM_KGDB_H |
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#define __ARM_KGDB_H |
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#include <linux/ptrace.h> |
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#include <asm/debug-monitors.h> |
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#ifndef __ASSEMBLY__ |
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static inline void arch_kgdb_breakpoint(void) |
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{ |
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asm ("brk %0" : : "I" (KGDB_COMPILED_DBG_BRK_IMM)); |
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} |
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extern void kgdb_handle_bus_error(void); |
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extern int kgdb_fault_expected; |
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#endif /* !__ASSEMBLY__ */ |
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/* |
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* gdb remote procotol (well most versions of it) expects the following |
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* register layout. |
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* |
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* General purpose regs: |
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* r0-r30: 64 bit |
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* sp,pc : 64 bit |
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* pstate : 32 bit |
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* Total: 33 + 1 |
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* FPU regs: |
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* f0-f31: 128 bit |
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* fpsr & fpcr: 32 bit |
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* Total: 32 + 2 |
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* |
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* To expand a little on the "most versions of it"... when the gdb remote |
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* protocol for AArch64 was developed it depended on a statement in the |
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* Architecture Reference Manual that claimed "SPSR_ELx is a 32-bit register". |
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* and, as a result, allocated only 32-bits for the PSTATE in the remote |
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* protocol. In fact this statement is still present in ARM DDI 0487A.i. |
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* |
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* Unfortunately "is a 32-bit register" has a very special meaning for |
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* system registers. It means that "the upper bits, bits[63:32], are |
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* RES0.". RES0 is heavily used in the ARM architecture documents as a |
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* way to leave space for future architecture changes. So to translate a |
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* little for people who don't spend their spare time reading ARM architecture |
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* manuals, what "is a 32-bit register" actually means in this context is |
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* "is a 64-bit register but one with no meaning allocated to any of the |
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* upper 32-bits... *yet*". |
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* |
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* Perhaps then we should not be surprised that this has led to some |
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* confusion. Specifically a patch, influenced by the above translation, |
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* that extended PSTATE to 64-bit was accepted into gdb-7.7 but the patch |
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* was reverted in gdb-7.8.1 and all later releases, when this was |
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* discovered to be an undocumented protocol change. |
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* |
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* So... it is *not* wrong for us to only allocate 32-bits to PSTATE |
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* here even though the kernel itself allocates 64-bits for the same |
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* state. That is because this bit of code tells the kernel how the gdb |
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* remote protocol (well most versions of it) describes the register state. |
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* |
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* Note that if you are using one of the versions of gdb that supports |
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* the gdb-7.7 version of the protocol you cannot use kgdb directly |
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* without providing a custom register description (gdb can load new |
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* protocol descriptions at runtime). |
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*/ |
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#define _GP_REGS 33 |
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#define _FP_REGS 32 |
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#define _EXTRA_REGS 3 |
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/* |
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* general purpose registers size in bytes. |
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* pstate is only 4 bytes. subtract 4 bytes |
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*/ |
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#define GP_REG_BYTES (_GP_REGS * 8) |
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#define DBG_MAX_REG_NUM (_GP_REGS + _FP_REGS + _EXTRA_REGS) |
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/* |
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* Size of I/O buffer for gdb packet. |
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* considering to hold all register contents, size is set |
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*/ |
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#define BUFMAX 2048 |
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/* |
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* Number of bytes required for gdb_regs buffer. |
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* _GP_REGS: 8 bytes, _FP_REGS: 16 bytes and _EXTRA_REGS: 4 bytes each |
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* GDB fails to connect for size beyond this with error |
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* "'g' packet reply is too long" |
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*/ |
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#define NUMREGBYTES ((_GP_REGS * 8) + (_FP_REGS * 16) + \ |
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(_EXTRA_REGS * 4)) |
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#endif /* __ASM_KGDB_H */
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