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af6c0bd59f
Currently only the first attempt to single-step has any effect. After
that all further stepping remains "stuck" at the same program counter
value.
Refer to the ARM Architecture Reference Manual (ARM DDI 0487E.a) D2.12,
PSTATE.SS=1 should be set at each step before transferring the PE to the
'Active-not-pending' state. The problem here is PSTATE.SS=1 is not set
since the second single-step.
After the first single-step, the PE transferes to the 'Inactive' state,
with PSTATE.SS=0 and MDSCR.SS=1, thus PSTATE.SS won't be set to 1 due to
kernel_active_single_step()=true. Then the PE transferes to the
'Active-pending' state when ERET and returns to the debugger by step
exception.
Before this patch:
==================
Entering kdb (current=0xffff3376039f0000, pid 1) on processor 0 due to Keyboard Entry
[0]kdb>
[0]kdb>
[0]kdb> bp write_sysrq_trigger
Instruction(i) BP #0 at 0xffffa45c13d09290 (write_sysrq_trigger)
is enabled addr at ffffa45c13d09290, hardtype=0 installed=0
[0]kdb> go
$ echo h > /proc/sysrq-trigger
Entering kdb (current=0xffff4f7e453f8000, pid 175) on processor 1 due to Breakpoint @ 0xffffad651a309290
[1]kdb> ss
Entering kdb (current=0xffff4f7e453f8000, pid 175) on processor 1 due to SS trap @ 0xffffad651a309294
[1]kdb> ss
Entering kdb (current=0xffff4f7e453f8000, pid 175) on processor 1 due to SS trap @ 0xffffad651a309294
[1]kdb>
After this patch:
=================
Entering kdb (current=0xffff6851c39f0000, pid 1) on processor 0 due to Keyboard Entry
[0]kdb> bp write_sysrq_trigger
Instruction(i) BP #0 at 0xffffc02d2dd09290 (write_sysrq_trigger)
is enabled addr at ffffc02d2dd09290, hardtype=0 installed=0
[0]kdb> go
$ echo h > /proc/sysrq-trigger
Entering kdb (current=0xffff6851c53c1840, pid 174) on processor 1 due to Breakpoint @ 0xffffc02d2dd09290
[1]kdb> ss
Entering kdb (current=0xffff6851c53c1840, pid 174) on processor 1 due to SS trap @ 0xffffc02d2dd09294
[1]kdb> ss
Entering kdb (current=0xffff6851c53c1840, pid 174) on processor 1 due to SS trap @ 0xffffc02d2dd09298
[1]kdb> ss
Entering kdb (current=0xffff6851c53c1840, pid 174) on processor 1 due to SS trap @ 0xffffc02d2dd0929c
[1]kdb>
Fixes: 44679a4f14 ("arm64: KGDB: Add step debugging support")
Co-developed-by: Wei Li <liwei391@huawei.com>
Signed-off-by: Wei Li <liwei391@huawei.com>
Signed-off-by: Sumit Garg <sumit.garg@linaro.org>
Tested-by: Douglas Anderson <dianders@chromium.org>
Acked-by: Daniel Thompson <daniel.thompson@linaro.org>
Tested-by: Daniel Thompson <daniel.thompson@linaro.org>
Link: https://lore.kernel.org/r/20230202073148.657746-3-sumit.garg@linaro.org
Signed-off-by: Will Deacon <will@kernel.org>
124 lines
3.2 KiB
C
124 lines
3.2 KiB
C
/* SPDX-License-Identifier: GPL-2.0-only */
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/*
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* Copyright (C) 2012 ARM Ltd.
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*/
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#ifndef __ASM_DEBUG_MONITORS_H
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#define __ASM_DEBUG_MONITORS_H
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#include <linux/errno.h>
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#include <linux/types.h>
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#include <asm/brk-imm.h>
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#include <asm/esr.h>
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#include <asm/insn.h>
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#include <asm/ptrace.h>
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/* Low-level stepping controls. */
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#define DBG_MDSCR_SS (1 << 0)
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#define DBG_SPSR_SS (1 << 21)
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/* MDSCR_EL1 enabling bits */
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#define DBG_MDSCR_KDE (1 << 13)
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#define DBG_MDSCR_MDE (1 << 15)
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#define DBG_MDSCR_MASK ~(DBG_MDSCR_KDE | DBG_MDSCR_MDE)
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#define DBG_ESR_EVT(x) (((x) >> 27) & 0x7)
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/* AArch64 */
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#define DBG_ESR_EVT_HWBP 0x0
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#define DBG_ESR_EVT_HWSS 0x1
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#define DBG_ESR_EVT_HWWP 0x2
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#define DBG_ESR_EVT_BRK 0x6
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/*
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* Break point instruction encoding
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*/
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#define BREAK_INSTR_SIZE AARCH64_INSN_SIZE
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#define AARCH64_BREAK_KGDB_DYN_DBG \
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(AARCH64_BREAK_MON | (KGDB_DYN_DBG_BRK_IMM << 5))
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#define CACHE_FLUSH_IS_SAFE 1
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/* kprobes BRK opcodes with ESR encoding */
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#define BRK64_OPCODE_KPROBES (AARCH64_BREAK_MON | (KPROBES_BRK_IMM << 5))
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#define BRK64_OPCODE_KPROBES_SS (AARCH64_BREAK_MON | (KPROBES_BRK_SS_IMM << 5))
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/* uprobes BRK opcodes with ESR encoding */
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#define BRK64_OPCODE_UPROBES (AARCH64_BREAK_MON | (UPROBES_BRK_IMM << 5))
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/* AArch32 */
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#define DBG_ESR_EVT_BKPT 0x4
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#define DBG_ESR_EVT_VECC 0x5
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#define AARCH32_BREAK_ARM 0x07f001f0
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#define AARCH32_BREAK_THUMB 0xde01
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#define AARCH32_BREAK_THUMB2_LO 0xf7f0
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#define AARCH32_BREAK_THUMB2_HI 0xa000
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#ifndef __ASSEMBLY__
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struct task_struct;
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#define DBG_ARCH_ID_RESERVED 0 /* In case of ptrace ABI updates. */
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#define DBG_HOOK_HANDLED 0
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#define DBG_HOOK_ERROR 1
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struct step_hook {
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struct list_head node;
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int (*fn)(struct pt_regs *regs, unsigned long esr);
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};
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void register_user_step_hook(struct step_hook *hook);
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void unregister_user_step_hook(struct step_hook *hook);
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void register_kernel_step_hook(struct step_hook *hook);
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void unregister_kernel_step_hook(struct step_hook *hook);
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struct break_hook {
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struct list_head node;
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int (*fn)(struct pt_regs *regs, unsigned long esr);
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u16 imm;
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u16 mask; /* These bits are ignored when comparing with imm */
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};
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void register_user_break_hook(struct break_hook *hook);
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void unregister_user_break_hook(struct break_hook *hook);
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void register_kernel_break_hook(struct break_hook *hook);
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void unregister_kernel_break_hook(struct break_hook *hook);
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u8 debug_monitors_arch(void);
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enum dbg_active_el {
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DBG_ACTIVE_EL0 = 0,
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DBG_ACTIVE_EL1,
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};
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void enable_debug_monitors(enum dbg_active_el el);
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void disable_debug_monitors(enum dbg_active_el el);
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void user_rewind_single_step(struct task_struct *task);
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void user_fastforward_single_step(struct task_struct *task);
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void user_regs_reset_single_step(struct user_pt_regs *regs,
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struct task_struct *task);
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void kernel_enable_single_step(struct pt_regs *regs);
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void kernel_disable_single_step(void);
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int kernel_active_single_step(void);
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void kernel_rewind_single_step(struct pt_regs *regs);
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#ifdef CONFIG_HAVE_HW_BREAKPOINT
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int reinstall_suspended_bps(struct pt_regs *regs);
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#else
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static inline int reinstall_suspended_bps(struct pt_regs *regs)
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{
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return -ENODEV;
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}
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#endif
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int aarch32_break_handler(struct pt_regs *regs);
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void debug_traps_init(void);
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#endif /* __ASSEMBLY */
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#endif /* __ASM_DEBUG_MONITORS_H */
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