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Date: Tue, 13 Dec 2022 20:06:42 +0800
From: Qing Zhang <zhangqing@...ngson.cn>
To: Jinyang He <hejinyang@...ngson.cn>,
Huacai Chen <chenhuacai@...nel.org>,
WANG Xuerui <kernel@...0n.name>
Cc: Jiaxun Yang <jiaxun.yang@...goat.com>, loongarch@...ts.linux.dev,
linux-kernel@...r.kernel.org
Subject: Re: [RFC PATCH] LoongArch: Add hardware breakpoints/watchpoints
support
Hi, Jinyang
On 2022/12/13 下午7:55, Jinyang He wrote:
> Hi, Qing,
>
>
> As it is a big patch with RFC title, I'll provide some style idea firstly.
>
>
> On 2022-12-13 17:10, qing zhang wrote:
>> From: Qing Zhang <zhangqing@...ngson.cn>
>>
>> Use perf framework to manage hardware instruction and data breakpoints.
>> LoongArch defines hardware watchpoint functions for instruction fetch
>> and load/store operations, after the software configures hardware
>> watchpoints
>> for instruction fetch and load/store operations. The processor
>> hardware will
>> monitor the access address of the instruction fetch and load/store
>> operation,
>> and will trigger the exception of the watchpoint when it meets the
>> conditions
>> set by the watchpoint.
>>
>> The hardware monitoring points for instruction fetching and load/store
>> operations
>> each have a register for the overall configuration of all monitoring
>> points,
>> a register for recording the status of all monitoring points, and four
>> registers
>> required for configuration of each watchpoint individually.
>>
>> Watchpoint related control status register chapters:
>> https://github.com/loongson/LoongArch-Documentation/releases/download/2022.08.12/
>>
>> LoongArch-Vol1-v1.02-CN.pdf
>>
>> Initial version has the following limitations:
>> - userspace debug is not yet enabled: work on ptrace/gdb is in progress
>> - no support for virtualization
>>
>> Despite missing userspace debug, initial implementation can be tested:
>> e.g.
>> see samples/hw_breakpoint and register_wide_hw_breakpoint.
>>
>> TODO:
>> - Add Kernel tools that use hardware breakpoints: Kgdb, Ptrace
>> - Add hardware breakpoints/watchpoints for gdb
>>
>> Signed-off-by: Qing Zhang <zhangqing@...ngson.cn>
>>
>> diff --git a/arch/loongarch/Kconfig b/arch/loongarch/Kconfig
>> index 12571eedc488..69199812fe74 100644
>> --- a/arch/loongarch/Kconfig
>> +++ b/arch/loongarch/Kconfig
>> @@ -99,6 +99,7 @@ config LOONGARCH
>> select HAVE_FUNCTION_GRAPH_TRACER
>> select HAVE_FUNCTION_TRACER
>> select HAVE_GENERIC_VDSO
>> + select HAVE_HW_BREAKPOINT if PERF_EVENTS
>> select HAVE_IOREMAP_PROT
>> select HAVE_IRQ_EXIT_ON_IRQ_STACK
>> select HAVE_IRQ_TIME_ACCOUNTING
>> diff --git a/arch/loongarch/include/asm/hw_breakpoint.h
>> b/arch/loongarch/include/asm/hw_breakpoint.h
>> new file mode 100644
>> index 000000000000..a57caf117960
>> --- /dev/null
>> +++ b/arch/loongarch/include/asm/hw_breakpoint.h
>> @@ -0,0 +1,140 @@
>> +/* SPDX-License-Identifier: GPL-2.0 */
>> +/*
>> + * Copyright (C) 2022 Loongson Technology Corporation Limited
>> + */
>> +#ifndef __ASM_HW_BREAKPOINT_H
>> +#define __ASM_HW_BREAKPOINT_H
>> +
>> +#include <asm/loongarch.h>
>> +
>> +#ifdef __KERNEL__
>> +
>> +/* Breakpoint */
>> +#define LOONGARCH_BREAKPOINT_EXECUTE (0 << 0)
>> +
>> +/* Watchpoints */
>> +#define LOONGARCH_BREAKPOINT_LOAD (1 << 0)
>> +#define LOONGARCH_BREAKPOINT_STORE (1 << 1)
>> +
>> +struct arch_hw_breakpoint_ctrl {
>> + u32 __reserved : 28,
>> + type : 2,
>> + len : 2;
>> +};
> It looks strange...
>> +
>> +struct arch_hw_breakpoint {
>> + u64 address;
>> + u64 mask;
>> + struct arch_hw_breakpoint_ctrl ctrl;
>> +};
>> +
>> +/* Lengths */
>> +#define LOONGARCH_BREAKPOINT_LEN_1 0b11
>> +#define LOONGARCH_BREAKPOINT_LEN_2 0b10
>> +#define LOONGARCH_BREAKPOINT_LEN_4 0b01
>> +#define LOONGARCH_BREAKPOINT_LEN_8 0b00
>> +
>> +/*
>> + * Limits.
>> + * Changing these will require modifications to the register accessors.
>> + */
>> +#define LOONGARCH_MAX_BRP 8
>> +#define LOONGARCH_MAX_WRP 8
>> +
>> +/* Virtual debug register bases. */
>> +#define CSR_CFG_ADDR 0
>> +#define CSR_CFG_MASK (CSR_CFG_ADDR + LOONGARCH_MAX_BRP)
>> +#define CSR_CFG_CTRL (CSR_CFG_MASK + LOONGARCH_MAX_BRP)
>> +#define CSR_CFG_ASID (CSR_CFG_CTRL + LOONGARCH_MAX_WRP)
>> +
>> +/* Debug register names. */
>> +#define LOONGARCH_CSR_NAME_ADDR ADDR
>> +#define LOONGARCH_CSR_NAME_MASK MASK
>> +#define LOONGARCH_CSR_NAME_CTRL CTRL
>> +#define LOONGARCH_CSR_NAME_ASID ASID
>> +
>> +/* Accessor macros for the debug registers. */
>> +#define LOONGARCH_CSR_READ(N, REG, T, VAL) \
>> +do { \
>> + if (T == 0) \
>> + VAL = csr_read64(LOONGARCH_CSR_##IB##N##REG); \
>> + else \
>> + VAL = csr_read64(LOONGARCH_CSR_##DB##N##REG); \
>> +} while (0)
>> +
>> +#define LOONGARCH_CSR_WRITE(N, REG, T, VAL) \
>> +do { \
>> + if (T == 0) \
>> + csr_write64(VAL, LOONGARCH_CSR_##IB##N##REG); \
>> + else \
>> + csr_write64(VAL, LOONGARCH_CSR_##DB##N##REG); \
>> +} while (0)
> The LOONGARCH_CSR_{READ, WRITE} are generic. As they are used locally, I
> think it's better to change their name.
>> +
>> +static inline u32 encode_ctrl_reg(struct arch_hw_breakpoint_ctrl ctrl)
>> +{
>> + u32 val = (ctrl.len << 2) | ctrl.type;
>> +
>> + return val;
>> +}
>> +
>> +static inline void decode_ctrl_reg(u32 reg, struct
>> arch_hw_breakpoint_ctrl *ctrl)
>> +{
>> + ctrl->type = reg & 0x3;
>> + reg >>= 2;
>> + ctrl->len = reg & 0x3;
>> +}
> Actually it is no need "& 0x3", but it is also OK and clear. How about
> support macros like HW_MASK_{TYPE, LEN}, HW_SHFIT_{TYPE, LEN}?
>> +
>> +struct task_struct;
>> +struct notifier_block;
>> +struct perf_event_attr;
>> +struct perf_event;
>> +
>> +extern int arch_bp_generic_fields(struct arch_hw_breakpoint_ctrl ctrl,
>> + int *gen_len, int *gen_type, int *offset);
>> +extern int arch_check_bp_in_kernelspace(struct arch_hw_breakpoint *hw);
>> +extern int hw_breakpoint_arch_parse(struct perf_event *bp,
>> + const struct perf_event_attr *attr,
>> + struct arch_hw_breakpoint *hw);
>> +extern int hw_breakpoint_exceptions_notify(struct notifier_block
>> *unused,
>> + unsigned long val, void *data);
>> +
>> +extern int arch_install_hw_breakpoint(struct perf_event *bp);
>> +extern void arch_uninstall_hw_breakpoint(struct perf_event *bp);
>> +extern void hw_breakpoint_pmu_read(struct perf_event *bp);
>> +extern int hw_breakpoint_slots(int type);
>> +
>> +int breakpoint_handler(struct pt_regs *regs);
>> +int watchpoint_handler(struct pt_regs *regs);
>> +
>> +#ifdef CONFIG_HAVE_HW_BREAKPOINT
>> +extern void hw_breakpoint_thread_switch(struct task_struct *next);
>> +extern void ptrace_hw_copy_thread(struct task_struct *task);
>> +#else
>> +static inline void hw_breakpoint_thread_switch(struct task_struct *next)
>> +{
>> +}
>> +static inline void ptrace_hw_copy_thread(struct task_struct *task)
>> +{
>> +}
>> +#endif
>> +
>> +/* Determine number of BRP registers available. */
>> +static inline int get_num_brps(void)
>> +{
>> + unsigned int ibcn;
>> +
>> + ibcn = csr_read64(LOONGARCH_CSR_FWPC) & 0x3f;
> And give mask macro here, too, for readability improvement.
>> + return ibcn;
>> +}
>> +
>> +/* Determine number of WRP registers available. */
>> +static inline int get_num_wrps(void)
>> +{
>> + unsigned int dbcn;
>> +
>> + dbcn = csr_read64(LOONGARCH_CSR_MWPC) & 0x3f;
>> + return dbcn;
>> +}
>> +
>> +#endif /* __KERNEL__ */
>> +#endif /* __ASM_BREAKPOINT_H */
>> diff --git a/arch/loongarch/include/asm/loongarch.h
>> b/arch/loongarch/include/asm/loongarch.h
>> index 7f8d57a61c8b..e9aed583a064 100644
>> --- a/arch/loongarch/include/asm/loongarch.h
>> +++ b/arch/loongarch/include/asm/loongarch.h
>> @@ -970,42 +970,42 @@ static __always_inline void iocsr_write64(u64
>> val, u32 reg)
>> #define LOONGARCH_CSR_DB0ADDR 0x310 /* data breakpoint 0
>> address */
>> #define LOONGARCH_CSR_DB0MASK 0x311 /* data breakpoint 0
>> mask */
>> -#define LOONGARCH_CSR_DB0CTL 0x312 /* data breakpoint 0
>> control */
>> +#define LOONGARCH_CSR_DB0CTRL 0x312 /* data breakpoint 0
>> control */
>> #define LOONGARCH_CSR_DB0ASID 0x313 /* data breakpoint 0
>> asid */
>> #define LOONGARCH_CSR_DB1ADDR 0x318 /* data breakpoint 1
>> address */
>> #define LOONGARCH_CSR_DB1MASK 0x319 /* data breakpoint 1
>> mask */
>> -#define LOONGARCH_CSR_DB1CTL 0x31a /* data breakpoint 1
>> control */
>> +#define LOONGARCH_CSR_DB1CTRL 0x31a /* data breakpoint 1
>> control */
>> #define LOONGARCH_CSR_DB1ASID 0x31b /* data breakpoint 1
>> asid */
>> #define LOONGARCH_CSR_DB2ADDR 0x320 /* data breakpoint 2
>> address */
>> #define LOONGARCH_CSR_DB2MASK 0x321 /* data breakpoint 2
>> mask */
>> -#define LOONGARCH_CSR_DB2CTL 0x322 /* data breakpoint 2
>> control */
>> +#define LOONGARCH_CSR_DB2CTRL 0x322 /* data breakpoint 2
>> control */
>> #define LOONGARCH_CSR_DB2ASID 0x323 /* data breakpoint 2
>> asid */
>> #define LOONGARCH_CSR_DB3ADDR 0x328 /* data breakpoint 3
>> address */
>> #define LOONGARCH_CSR_DB3MASK 0x329 /* data breakpoint 3
>> mask */
>> -#define LOONGARCH_CSR_DB3CTL 0x32a /* data breakpoint 3
>> control */
>> +#define LOONGARCH_CSR_DB3CTRL 0x32a /* data breakpoint 3
>> control */
>> #define LOONGARCH_CSR_DB3ASID 0x32b /* data breakpoint 3
>> asid */
>> #define LOONGARCH_CSR_DB4ADDR 0x330 /* data breakpoint 4
>> address */
>> #define LOONGARCH_CSR_DB4MASK 0x331 /* data breakpoint 4
>> maks */
>> -#define LOONGARCH_CSR_DB4CTL 0x332 /* data breakpoint 4
>> control */
>> +#define LOONGARCH_CSR_DB4CTRL 0x332 /* data breakpoint 4
>> control */
>> #define LOONGARCH_CSR_DB4ASID 0x333 /* data breakpoint 4
>> asid */
>> #define LOONGARCH_CSR_DB5ADDR 0x338 /* data breakpoint 5
>> address */
>> #define LOONGARCH_CSR_DB5MASK 0x339 /* data breakpoint 5
>> mask */
>> -#define LOONGARCH_CSR_DB5CTL 0x33a /* data breakpoint 5
>> control */
>> +#define LOONGARCH_CSR_DB5CTRL 0x33a /* data breakpoint 5
>> control */
>> #define LOONGARCH_CSR_DB5ASID 0x33b /* data breakpoint 5
>> asid */
>> #define LOONGARCH_CSR_DB6ADDR 0x340 /* data breakpoint 6
>> address */
>> #define LOONGARCH_CSR_DB6MASK 0x341 /* data breakpoint 6
>> mask */
>> -#define LOONGARCH_CSR_DB6CTL 0x342 /* data breakpoint 6
>> control */
>> +#define LOONGARCH_CSR_DB6CTRL 0x342 /* data breakpoint 6
>> control */
>> #define LOONGARCH_CSR_DB6ASID 0x343 /* data breakpoint 6
>> asid */
>> #define LOONGARCH_CSR_DB7ADDR 0x348 /* data breakpoint 7
>> address */
>> #define LOONGARCH_CSR_DB7MASK 0x349 /* data breakpoint 7
>> mask */
>> -#define LOONGARCH_CSR_DB7CTL 0x34a /* data breakpoint 7
>> control */
>> +#define LOONGARCH_CSR_DB7CTRL 0x34a /* data breakpoint 7
>> control */
>> #define LOONGARCH_CSR_DB7ASID 0x34b /* data breakpoint 7
>> asid */
>> #define LOONGARCH_CSR_FWPC 0x380 /* instruction breakpoint
>> config */
>> @@ -1013,42 +1013,42 @@ static __always_inline void iocsr_write64(u64
>> val, u32 reg)
>> #define LOONGARCH_CSR_IB0ADDR 0x390 /* inst breakpoint 0
>> address */
>> #define LOONGARCH_CSR_IB0MASK 0x391 /* inst breakpoint 0
>> mask */
>> -#define LOONGARCH_CSR_IB0CTL 0x392 /* inst breakpoint 0
>> control */
>> +#define LOONGARCH_CSR_IB0CTRL 0x392 /* inst breakpoint 0
>> control */
>> #define LOONGARCH_CSR_IB0ASID 0x393 /* inst breakpoint 0
>> asid */
>> #define LOONGARCH_CSR_IB1ADDR 0x398 /* inst breakpoint 1
>> address */
>> #define LOONGARCH_CSR_IB1MASK 0x399 /* inst breakpoint 1
>> mask */
>> -#define LOONGARCH_CSR_IB1CTL 0x39a /* inst breakpoint 1
>> control */
>> +#define LOONGARCH_CSR_IB1CTRL 0x39a /* inst breakpoint 1
>> control */
>> #define LOONGARCH_CSR_IB1ASID 0x39b /* inst breakpoint 1
>> asid */
>> #define LOONGARCH_CSR_IB2ADDR 0x3a0 /* inst breakpoint 2
>> address */
>> #define LOONGARCH_CSR_IB2MASK 0x3a1 /* inst breakpoint 2
>> mask */
>> -#define LOONGARCH_CSR_IB2CTL 0x3a2 /* inst breakpoint 2
>> control */
>> +#define LOONGARCH_CSR_IB2CTRL 0x3a2 /* inst breakpoint 2
>> control */
>> #define LOONGARCH_CSR_IB2ASID 0x3a3 /* inst breakpoint 2
>> asid */
>> #define LOONGARCH_CSR_IB3ADDR 0x3a8 /* inst breakpoint 3
>> address */
>> #define LOONGARCH_CSR_IB3MASK 0x3a9 /* breakpoint 3 mask */
>> -#define LOONGARCH_CSR_IB3CTL 0x3aa /* inst breakpoint 3
>> control */
>> +#define LOONGARCH_CSR_IB3CTRL 0x3aa /* inst breakpoint 3
>> control */
>> #define LOONGARCH_CSR_IB3ASID 0x3ab /* inst breakpoint 3
>> asid */
>> #define LOONGARCH_CSR_IB4ADDR 0x3b0 /* inst breakpoint 4
>> address */
>> #define LOONGARCH_CSR_IB4MASK 0x3b1 /* inst breakpoint 4
>> mask */
>> -#define LOONGARCH_CSR_IB4CTL 0x3b2 /* inst breakpoint 4
>> control */
>> +#define LOONGARCH_CSR_IB4CTRL 0x3b2 /* inst breakpoint 4
>> control */
>> #define LOONGARCH_CSR_IB4ASID 0x3b3 /* inst breakpoint 4
>> asid */
>> #define LOONGARCH_CSR_IB5ADDR 0x3b8 /* inst breakpoint 5
>> address */
>> #define LOONGARCH_CSR_IB5MASK 0x3b9 /* inst breakpoint 5
>> mask */
>> -#define LOONGARCH_CSR_IB5CTL 0x3ba /* inst breakpoint 5
>> control */
>> +#define LOONGARCH_CSR_IB5CTRL 0x3ba /* inst breakpoint 5
>> control */
>> #define LOONGARCH_CSR_IB5ASID 0x3bb /* inst breakpoint 5
>> asid */
>> #define LOONGARCH_CSR_IB6ADDR 0x3c0 /* inst breakpoint 6
>> address */
>> #define LOONGARCH_CSR_IB6MASK 0x3c1 /* inst breakpoint 6
>> mask */
>> -#define LOONGARCH_CSR_IB6CTL 0x3c2 /* inst breakpoint 6
>> control */
>> +#define LOONGARCH_CSR_IB6CTRL 0x3c2 /* inst breakpoint 6
>> control */
>> #define LOONGARCH_CSR_IB6ASID 0x3c3 /* inst breakpoint 6
>> asid */
>> #define LOONGARCH_CSR_IB7ADDR 0x3c8 /* inst breakpoint 7
>> address */
>> #define LOONGARCH_CSR_IB7MASK 0x3c9 /* inst breakpoint 7
>> mask */
>> -#define LOONGARCH_CSR_IB7CTL 0x3ca /* inst breakpoint 7
>> control */
>> +#define LOONGARCH_CSR_IB7CTRL 0x3ca /* inst breakpoint 7
>> control */
>> #define LOONGARCH_CSR_IB7ASID 0x3cb /* inst breakpoint 7
>> asid */
>> #define LOONGARCH_CSR_DEBUG 0x500 /* debug config */
>> diff --git a/arch/loongarch/include/asm/processor.h
>> b/arch/loongarch/include/asm/processor.h
>> index 7184f1dc61f2..f6ee920122d6 100644
>> --- a/arch/loongarch/include/asm/processor.h
>> +++ b/arch/loongarch/include/asm/processor.h
>> @@ -11,6 +11,7 @@
>> #include <asm/cpu.h>
>> #include <asm/cpu-info.h>
>> +#include <asm/hw_breakpoint.h>
>> #include <asm/loongarch.h>
>> #include <asm/vdso/processor.h>
>> #include <uapi/asm/ptrace.h>
>> @@ -131,6 +132,9 @@ struct thread_struct {
>> * they are conditionally copied at fork().
>> */
>> struct loongarch_fpu fpu FPU_ALIGN;
>> + /* Hardware breakpoints pinned to this task. */
>> + struct perf_event *hbp_break[LOONGARCH_MAX_BRP];
>> + struct perf_event *hbp_watch[LOONGARCH_MAX_WRP];
>> };
>> #define thread_saved_ra(tsk) (tsk->thread.sched_ra)
>> @@ -172,6 +176,8 @@ struct thread_struct {
>> .fcc = 0, \
>> .fpr = {{{0,},},}, \
>> }, \
>> + .hbp_break = {0}, \
>> + .hbp_watch = {0}, \
>> }
>> struct task_struct;
>> @@ -184,10 +190,6 @@ extern unsigned long
>> boot_option_idle_override;
>> */
>> extern void start_thread(struct pt_regs *regs, unsigned long pc,
>> unsigned long sp);
>> -static inline void flush_thread(void)
>> -{
>> -}
>> -
>> unsigned long __get_wchan(struct task_struct *p);
>> #define __KSTK_TOS(tsk) ((unsigned long)task_stack_page(tsk) + \
>> diff --git a/arch/loongarch/include/asm/switch_to.h
>> b/arch/loongarch/include/asm/switch_to.h
>> index 43a5ab162d38..24e3094bebab 100644
>> --- a/arch/loongarch/include/asm/switch_to.h
>> +++ b/arch/loongarch/include/asm/switch_to.h
>> @@ -34,6 +34,7 @@ extern asmlinkage struct task_struct
>> *__switch_to(struct task_struct *prev,
>> #define switch_to(prev, next, last) \
>> do { \
>> lose_fpu_inatomic(1, prev); \
>> + hw_breakpoint_thread_switch(next); \
>> (last) = __switch_to(prev, next, task_thread_info(next), \
>> __builtin_return_address(0), __builtin_frame_address(0)); \
>> } while (0)
>> diff --git a/arch/loongarch/kernel/Makefile
>> b/arch/loongarch/kernel/Makefile
>> index 7ca65195f7f8..b3aca7f2296e 100644
>> --- a/arch/loongarch/kernel/Makefile
>> +++ b/arch/loongarch/kernel/Makefile
>> @@ -46,6 +46,7 @@ obj-$(CONFIG_UNWINDER_GUESS) += unwind_guess.o
>> obj-$(CONFIG_UNWINDER_PROLOGUE) += unwind_prologue.o
>> obj-$(CONFIG_PERF_EVENTS) += perf_event.o perf_regs.o
>> +obj-$(CONFIG_HAVE_HW_BREAKPOINT) += hw_breakpoint.o
>> obj-$(CONFIG_KPROBES) += kprobes.o kprobes_trampoline.o
>> diff --git a/arch/loongarch/kernel/hw_breakpoint.c
>> b/arch/loongarch/kernel/hw_breakpoint.c
>> new file mode 100644
>> index 000000000000..16f38ceec321
>> --- /dev/null
>> +++ b/arch/loongarch/kernel/hw_breakpoint.c
>> @@ -0,0 +1,461 @@
>> +// SPDX-License-Identifier: GPL-2.0
>> +/*
>> + * Copyright (C) 2022 Loongson Technology Corporation Limited
>> + */
>> +#define pr_fmt(fmt) "hw-breakpoint: " fmt
>> +
>> +#include <linux/hw_breakpoint.h>
>> +#include <linux/kprobes.h>
>> +#include <linux/perf_event.h>
>> +
>> +#include <asm/hw_breakpoint.h>
>> +
>> +/* Breakpoint currently in use for each BRP. */
>> +static DEFINE_PER_CPU(struct perf_event *,
>> bp_on_reg[LOONGARCH_MAX_BRP]);
>> +
>> +/* Watchpoint currently in use for each WRP. */
>> +static DEFINE_PER_CPU(struct perf_event *,
>> wp_on_reg[LOONGARCH_MAX_WRP]);
>> +
>> +/* Number of BRP/WRP registers on this CPU. */
>> +static int core_num_brps;
>> +static int core_num_wrps;
>> +
>> +int hw_breakpoint_slots(int type)
>> +{
>> + /*
>> + * We can be called early, so don't rely on
>> + * our static variables being initialised.
>> + */
>> + switch (type) {
>> + case TYPE_INST:
>> + return get_num_brps();
>> + case TYPE_DATA:
>> + return get_num_wrps();
>> + default:
>> + pr_warn("unknown slot type: %d\n", type);
>> + return 0;
>> + }
>> +}
>> +
>> +#define READ_WB_REG_CASE(OFF, N, REG, T, VAL) \
>> + case (OFF + N): \
>> + LOONGARCH_CSR_READ(N, REG, T, VAL); \
>> + break
>> +
>> +#define WRITE_WB_REG_CASE(OFF, N, REG, T, VAL) \
>> + case (OFF + N): \
>> + LOONGARCH_CSR_WRITE(N, REG, T, VAL); \
>> + break
>> +
>> +#define GEN_READ_WB_REG_CASES(OFF, REG, T, VAL) \
>> + READ_WB_REG_CASE(OFF, 0, REG, T, VAL); \
>> + READ_WB_REG_CASE(OFF, 1, REG, T, VAL); \
>> + READ_WB_REG_CASE(OFF, 2, REG, T, VAL); \
>> + READ_WB_REG_CASE(OFF, 3, REG, T, VAL); \
>> + READ_WB_REG_CASE(OFF, 4, REG, T, VAL); \
>> + READ_WB_REG_CASE(OFF, 5, REG, T, VAL); \
>> + READ_WB_REG_CASE(OFF, 6, REG, T, VAL); \
>> + READ_WB_REG_CASE(OFF, 7, REG, T, VAL);
>> +
>> +#define GEN_WRITE_WB_REG_CASES(OFF, REG, T, VAL) \
>> + WRITE_WB_REG_CASE(OFF, 0, REG, T, VAL); \
>> + WRITE_WB_REG_CASE(OFF, 1, REG, T, VAL); \
>> + WRITE_WB_REG_CASE(OFF, 2, REG, T, VAL); \
>> + WRITE_WB_REG_CASE(OFF, 3, REG, T, VAL); \
>> + WRITE_WB_REG_CASE(OFF, 4, REG, T, VAL); \
>> + WRITE_WB_REG_CASE(OFF, 5, REG, T, VAL); \
>> + WRITE_WB_REG_CASE(OFF, 6, REG, T, VAL); \
>> + WRITE_WB_REG_CASE(OFF, 7, REG, T, VAL);
>> +
>> +static u64 read_wb_reg(int reg, int n, int t)
>> +{
>> + u64 val = 0;
>> +
>> + switch (reg + n) {
>> + GEN_READ_WB_REG_CASES(CSR_CFG_ADDR, ADDR, t, val);
>> + GEN_READ_WB_REG_CASES(CSR_CFG_MASK, MASK, t, val);
>> + GEN_READ_WB_REG_CASES(CSR_CFG_CTRL, CTRL, t, val);
>> + GEN_READ_WB_REG_CASES(CSR_CFG_ASID, ASID, t, val);
>> + default:
>> + pr_warn("attempt to read from unknown breakpoint register
>> %d\n", n);
>> + }
>> +
>> + return val;
>> +}
>> +NOKPROBE_SYMBOL(read_wb_reg);
>> +
>> +static void write_wb_reg(int reg, int n, int t, u64 val)
>> +{
>> + switch (reg + n) {
>> + GEN_WRITE_WB_REG_CASES(CSR_CFG_ADDR, ADDR, t, val);
>> + GEN_WRITE_WB_REG_CASES(CSR_CFG_MASK, MASK, t, val);
>> + GEN_WRITE_WB_REG_CASES(CSR_CFG_CTRL, CTRL, t, val);
>> + GEN_WRITE_WB_REG_CASES(CSR_CFG_ASID, ASID, t, val);
>> + default:
>> + pr_warn("attempt to write to unknown breakpoint register
>> %d\n", n);
>> + }
>> +}
>> +NOKPROBE_SYMBOL(write_wb_reg);
>> +
>> +enum hw_breakpoint_ops {
>> + HW_BREAKPOINT_INSTALL,
>> + HW_BREAKPOINT_UNINSTALL,
>> +};
>> +
>> +/**
>> + * hw_breakpoint_slot_setup - Find and setup a perf slot according to
>> + * operations
>> + *
>> + * @slots: pointer to array of slots
>> + * @max_slots: max number of slots
>> + * @bp: perf_event to setup
>> + * @ops: operation to be carried out on the slot
>> + *
>> + * Return:
>> + * slot index on success
>> + * -ENOSPC if no slot is available/matches
>> + * -EINVAL on wrong operations parameter
>> + */
>> +static int hw_breakpoint_slot_setup(struct perf_event **slots, int
>> max_slots,
>> + struct perf_event *bp,
>> + enum hw_breakpoint_ops ops)
>> +{
>> + int i;
>> + struct perf_event **slot;
>> +
>> + for (i = 0; i < max_slots; ++i) {
>> + slot = &slots[i];
>> + switch (ops) {
>> + case HW_BREAKPOINT_INSTALL:
>> + if (!*slot) {
>> + *slot = bp;
>> + return i;
>> + }
>> + break;
>> + case HW_BREAKPOINT_UNINSTALL:
>> + if (*slot == bp) {
>> + *slot = NULL;
>> + return i;
>> + }
>> + break;
>> + default:
>> + pr_warn_once("Unhandled hw breakpoint ops %d\n", ops);
>> + return -EINVAL;
>> + }
>> + }
>> + return -ENOSPC;
>> +}
>> +
>> +/*
>> + * Unregister breakpoints from this task and reset the pointers in
>> + * the thread_struct.
>> + */
>> +void flush_ptrace_hw_breakpoint(struct task_struct *tsk)
>> +{
>> +}
>> +
>> +void ptrace_hw_copy_thread(struct task_struct *tsk)
>> +{
>> + memset(&tsk->thread.hbp_break, 0, sizeof(tsk->thread.hbp_break));
>> + memset(&tsk->thread.hbp_watch, 0, sizeof(tsk->thread.hbp_watch));
>> +}
>> +
>> +static int hw_breakpoint_control(struct perf_event *bp,
>> + enum hw_breakpoint_ops ops)
>> +{
>> + struct arch_hw_breakpoint *info = counter_arch_bp(bp);
>> + struct perf_event **slots;
>> + int i, max_slots, enable;
>> + u32 ctrl;
>> + struct pt_regs *regs = task_pt_regs(current);
>> +
>> + if (info->ctrl.type == LOONGARCH_BREAKPOINT_EXECUTE) {
>> + /* Breakpoint */
>> + slots = this_cpu_ptr(bp_on_reg);
>> + max_slots = core_num_brps;
>> + } else {
>> + /* Watchpoint */
>> + slots = this_cpu_ptr(wp_on_reg);
>> + max_slots = core_num_wrps;
>> + }
>> +
>> + i = hw_breakpoint_slot_setup(slots, max_slots, bp, ops);
>> +
>> + if (WARN_ONCE(i < 0, "Can't find any breakpoint slot"))
>> + return i;
>> +
>> + switch (ops) {
>> + case HW_BREAKPOINT_INSTALL:
>> + /* Set the FWPnCFG/MWPnCFG 1~3 register. */
>> + write_wb_reg(CSR_CFG_ADDR, i, 0, info->address);
>> + write_wb_reg(CSR_CFG_ADDR, i, 1, info->address);
>> + if (info->mask) {
>> + write_wb_reg(CSR_CFG_MASK, i, 0, info->mask);
>> + write_wb_reg(CSR_CFG_MASK, i, 1, info->mask);
>> + }
>> + write_wb_reg(CSR_CFG_ASID, i, 0, 0);
>> + write_wb_reg(CSR_CFG_ASID, i, 1, 0);
>> + ctrl = encode_ctrl_reg(info->ctrl);
>> + if (info->ctrl.type == LOONGARCH_BREAKPOINT_EXECUTE)
>> + write_wb_reg(CSR_CFG_CTRL, i, 0, ctrl | 0x1e);
>> + else
>> + write_wb_reg(CSR_CFG_CTRL, i, 1, ctrl | 0x1e | 1 << 8 |
>> 1 << 9);
>> +
>> + enable = csr_read64(LOONGARCH_CSR_CRMD);
>> + csr_write64(1 << 9 | enable, LOONGARCH_CSR_CRMD);
>> + break;
>> + case HW_BREAKPOINT_UNINSTALL:
>> + /* Reset the FWPnCFG/MWPnCFG 1~3 register. */
>> + write_wb_reg(CSR_CFG_ADDR, i, 0, 0);
>> + write_wb_reg(CSR_CFG_ADDR, i, 1, 0);
>> + write_wb_reg(CSR_CFG_MASK, i, 0, 0);
>> + write_wb_reg(CSR_CFG_MASK, i, 1, 0);
>> + write_wb_reg(CSR_CFG_CTRL, i, 0, 0);
>> + write_wb_reg(CSR_CFG_CTRL, i, 1, 0);
>> + write_wb_reg(CSR_CFG_ASID, i, 0, 0);
>> + write_wb_reg(CSR_CFG_ASID, i, 1, 0);
>> + break;
>> + }
>> +
>> + return 0;
>> +}
>> +
>> +/*
>> + * Install a perf counter breakpoint.
>> + */
>> +int arch_install_hw_breakpoint(struct perf_event *bp)
>> +{
>> + return hw_breakpoint_control(bp, HW_BREAKPOINT_INSTALL);
>> +}
>> +
>> +void arch_uninstall_hw_breakpoint(struct perf_event *bp)
>> +{
>> + hw_breakpoint_control(bp, HW_BREAKPOINT_UNINSTALL);
>> +}
>> +
>> +static int get_hbp_len(u8 hbp_len)
> An array for simplify.
>> +{
>> + unsigned int len_in_bytes = 0;
>> +
>> + switch (hbp_len) {
>> + case LOONGARCH_BREAKPOINT_LEN_1:
>> + len_in_bytes = 1;
>> + break;
>> + case LOONGARCH_BREAKPOINT_LEN_2:
>> + len_in_bytes = 2;
>> + break;
>> + case LOONGARCH_BREAKPOINT_LEN_4:
>> + len_in_bytes = 4;
>> + break;
>> + case LOONGARCH_BREAKPOINT_LEN_8:
>> + len_in_bytes = 8;
>> + break;
>> + }
>> +
>> + return len_in_bytes;
>> +}
>> +
>> +/*
>> + * Check whether bp virtual address is in kernel space.
>> + */
>> +int arch_check_bp_in_kernelspace(struct arch_hw_breakpoint *hw)
>> +{
>> + unsigned int len;
>> + unsigned long va;
>> +
>> + va = hw->address;
>> + len = get_hbp_len(hw->ctrl.len);
>> +
>> + return (va >= TASK_SIZE) && ((va + len - 1) >= TASK_SIZE);
>> +}
>> +
>> +/*
>> + * Construct an arch_hw_breakpoint from a perf_event.
>> + */
>> +static int arch_build_bp_info(struct perf_event *bp,
>> + const struct perf_event_attr *attr,
>> + struct arch_hw_breakpoint *hw)
>> +{
>> + /* Type */
>> + switch (attr->bp_type) {
>> + case HW_BREAKPOINT_X:
>> + hw->ctrl.type = LOONGARCH_BREAKPOINT_EXECUTE;
>> + break;
>> + case HW_BREAKPOINT_R:
>> + hw->ctrl.type = LOONGARCH_BREAKPOINT_LOAD;
>> + break;
>> + case HW_BREAKPOINT_W:
>> + hw->ctrl.type = LOONGARCH_BREAKPOINT_STORE;
>> + break;
>> + case HW_BREAKPOINT_RW:
>> + hw->ctrl.type = LOONGARCH_BREAKPOINT_LOAD |
>> LOONGARCH_BREAKPOINT_STORE;
>> + break;
>> + default:
>> + return -EINVAL;
>> + }
>> +
>> + /* Len */
>> + switch (attr->bp_len) {
>> + case HW_BREAKPOINT_LEN_1:
>> + hw->ctrl.len = LOONGARCH_BREAKPOINT_LEN_1;
>> + break;
>> + case HW_BREAKPOINT_LEN_2:
>> + hw->ctrl.len = LOONGARCH_BREAKPOINT_LEN_2;
>> + break;
>> + case HW_BREAKPOINT_LEN_4:
>> + hw->ctrl.len = LOONGARCH_BREAKPOINT_LEN_4;
>> + break;
>> + case HW_BREAKPOINT_LEN_8:
>> + hw->ctrl.len = LOONGARCH_BREAKPOINT_LEN_8;
>> + break;
>> + default:
>> + return -EINVAL;
>> + }
>> +
>> + /* Address */
>> + hw->address = attr->bp_addr;
>> +
>> + return 0;
>> +}
>> +
>> +/*
>> + * Validate the arch-specific HW Breakpoint register settings.
>> + */
>> +int hw_breakpoint_arch_parse(struct perf_event *bp,
>> + const struct perf_event_attr *attr,
>> + struct arch_hw_breakpoint *hw)
>> +{
>> + int ret;
>> + u64 alignment_mask, offset;
>> +
>> + /* Build the arch_hw_breakpoint. */
>> + ret = arch_build_bp_info(bp, attr, hw);
>> + if (ret)
>> + return ret;
>> +
>> + if (hw->ctrl.type != LOONGARCH_BREAKPOINT_EXECUTE)
>> + alignment_mask = 0x7;
>> + offset = hw->address & alignment_mask;
>> +
>> + hw->address &= ~alignment_mask;
>> + hw->ctrl.len <<= offset;
>> +
>> + return 0;
>> +}
>> +
>> +#define PRMD_WE (1UL<<3) /*prmd watch enable, restore to crmd when
>> eret*/
>> +static void update_bp_registers(struct pt_regs *regs, int enable)
> Use macro in this function for ...
>> +{
>> + int i, max_slots;
>> + u32 ctrl;
>> + struct perf_event **slots;
>> +
>> + if (csr_read64(LOONGARCH_CSR_FWPS) & 0xff) {
>> + slots = this_cpu_ptr(bp_on_reg);
>> + max_slots = core_num_brps;
>> +
>> + } else if (csr_read64(LOONGARCH_CSR_MWPS) & 0xff) {
>> + slots = this_cpu_ptr(wp_on_reg);
>> + max_slots = core_num_wrps;
>> + } else {
>> + return;
>> + }
>> +
>> + for (i = 0; i < max_slots; ++i) {
>> + if (!slots[i])
>> + continue;
>> +
>> + ctrl = read_wb_reg(CSR_CFG_CTRL, i, 1);
>> + if (enable) {
>> + ctrl = read_wb_reg(CSR_CFG_CTRL, i, 1);
>> + ctrl |= 0x1 << 8;
>> + ctrl |= 0x1 << 9;
>> + write_wb_reg(CSR_CFG_CTRL, i, 1, ctrl);
>> + regs->csr_prmd |= PRMD_WE;
>> + } else {
>> + ctrl = read_wb_reg(CSR_CFG_CTRL, i, 1);
>> + ctrl &= ~0x1 << 8;
>> + ctrl &= ~0x1 << 9;
>> + write_wb_reg(CSR_CFG_CTRL, i, 1, ctrl);
>> + regs->csr_prmd &= ~PRMD_WE;
>> + }
>> + }
>> +}
>> +NOKPROBE_SYMBOL(update_bp_registers);
>> +
>> +/*
>> + * Debug exception handlers.
>> + */
>> +int breakpoint_handler(struct pt_regs *regs)
>> +{
>> + int i;
>> + u64 addr;
>> + struct perf_event *bp, **slots;
>> +
>> + slots = this_cpu_ptr(bp_on_reg);
>> +
>> + for (i = 0; i < core_num_brps; ++i) {
>> + bp = slots[i];
>> + if (bp == NULL)
>> + continue;
>> + perf_bp_event(bp, regs);
>> + }
>> + update_bp_registers(regs, 0);
>> +
>> + return 0;
>> +}
>> +NOKPROBE_SYMBOL(breakpoint_handler);
>> +
>> +int watchpoint_handler(struct pt_regs *regs)
>> +{
>> + int i;
>> + struct perf_event *wp, **slots;
>> +
>> + slots = this_cpu_ptr(wp_on_reg);
>> +
>> + for (i = 0; i < core_num_wrps; ++i) {
>> + wp = slots[i];
>> + if (wp == NULL)
>> + continue;
>> + perf_bp_event(wp, regs);
>> + }
>> + update_bp_registers(regs, 0);
>> +
>> + return 0;
>> +}
>> +NOKPROBE_SYMBOL(watchpoint_handler);
>> +
>> +/*
>> + * One-time initialisation.
>> + */
>> +static int __init arch_hw_breakpoint_init(void)
>> +{
>> + core_num_brps = get_num_brps();
>> + core_num_wrps = get_num_wrps();
>> +
>> + pr_info("found %d breakpoint and %d watchpoint registers.\n",
>> + core_num_brps, core_num_wrps);
>> + return 0;
>> +}
>> +arch_initcall(arch_hw_breakpoint_init);
>> +
>> +void hw_breakpoint_thread_switch(struct task_struct *next)
>> +{
>> + struct pt_regs *regs = task_pt_regs(next);
>> +
>> + /* Update breakpoints/watchpoints. */
>> + update_bp_registers(regs, 1);
>> +}
>> +
>> +void hw_breakpoint_pmu_read(struct perf_event *bp)
>> +{
>> +}
>> +
>> +/*
>> + * Dummy function to register with die_notifier.
>> + */
>> +int hw_breakpoint_exceptions_notify(struct notifier_block *unused,
>> + unsigned long val, void *data)
>> +{
>> + return NOTIFY_DONE;
>> +}
>> diff --git a/arch/loongarch/kernel/process.c
>> b/arch/loongarch/kernel/process.c
>> index 27c8cacbce01..f78574562329 100644
>> --- a/arch/loongarch/kernel/process.c
>> +++ b/arch/loongarch/kernel/process.c
>> @@ -37,6 +37,7 @@
>> #include <asm/cpu.h>
>> #include <asm/elf.h>
>> #include <asm/fpu.h>
>> +#include <linux/hw_breakpoint.h>
> ...
>> #include <asm/io.h>
>> #include <asm/irq.h>
>> #include <asm/irq_regs.h>
>> @@ -100,6 +101,11 @@ void exit_thread(struct task_struct *tsk)
>> {
>> }
>> +void flush_thread(void)
>> +{
>> + flush_ptrace_hw_breakpoint(current);
>> +}
>> +
>> int arch_dup_task_struct(struct task_struct *dst, struct task_struct
>> *src)
>> {
>> /*
>> @@ -186,6 +192,8 @@ int copy_thread(struct task_struct *p, const
>> struct kernel_clone_args *args)
>> if (clone_flags & CLONE_SETTLS)
>> childregs->regs[2] = tls;
>> + ptrace_hw_copy_thread(p);
>> +
>> out:
>> clear_tsk_thread_flag(p, TIF_USEDFPU);
>> clear_tsk_thread_flag(p, TIF_USEDSIMD);
>> diff --git a/arch/loongarch/kernel/traps.c
>> b/arch/loongarch/kernel/traps.c
>> index 4d9f77565703..d59cf93a4c31 100644
>> --- a/arch/loongarch/kernel/traps.c
>> +++ b/arch/loongarch/kernel/traps.c
>> @@ -45,6 +45,7 @@
>> #include <asm/tlb.h>
>> #include <asm/types.h>
>> #include <asm/unwind.h>
>> +#include <asm/hw_breakpoint.h>
>> #include "access-helper.h"
>> @@ -514,7 +515,19 @@ asmlinkage void noinstr do_bp(struct pt_regs *regs)
>> asmlinkage void noinstr do_watch(struct pt_regs *regs)
>> {
>> - pr_warn("Hardware watch point handler not implemented!\n");
>> + enum ctx_state prev_state;
>> +
>> + prev_state = exception_enter();
>> +
>> +#ifdef CONFIG_HAVE_HW_BREAKPOINT
>> + if (breakpoint_handler(regs))
>> + return;
>> + if (watchpoint_handler(regs))
>> + return;
>> +#endif
>> + force_sig(SIGTRAP);
>> + exception_exit(prev_state);
>> + return;
>> }
>> asmlinkage void noinstr do_ri(struct pt_regs *regs)
Thanks for your suggestions, they are useful, I'll make some more
details to improve.
Thanks,
-Qing
>
> Thanks,
>
> jinyang
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