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Date: Sat, 11 Feb 2023 13:24:30 +0800
From: Jinyang He <hejinyang@...ngson.cn>
To: Qing Zhang <zhangqing@...ngson.cn>,
Huacai Chen <chenhuacai@...nel.org>,
Oleg Nesterov <oleg@...hat.com>,
WANG Xuerui <kernel@...0n.name>
Cc: Jiaxun Yang <jiaxun.yang@...goat.com>, loongarch@...ts.linux.dev,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 1/3] LoongArch: Add hardware breakpoints/watchpoints
support
Hi, Qing,
On 2023-02-10 18:09, Qing Zhang wrote:
> 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.
>
> Signed-off-by: Qing Zhang <zhangqing@...ngson.cn>
> ---
> arch/loongarch/Kconfig | 1 +
> arch/loongarch/include/asm/hw_breakpoint.h | 145 ++++++
> arch/loongarch/include/asm/loongarch.h | 32 +-
> arch/loongarch/include/asm/processor.h | 11 +-
> arch/loongarch/include/asm/switch_to.h | 1 +
> arch/loongarch/kernel/Makefile | 1 +
> arch/loongarch/kernel/hw_breakpoint.c | 517 +++++++++++++++++++++
> arch/loongarch/kernel/process.c | 7 +
> arch/loongarch/kernel/traps.c | 14 +-
> 9 files changed, 708 insertions(+), 21 deletions(-)
> create mode 100644 arch/loongarch/include/asm/hw_breakpoint.h
> create mode 100644 arch/loongarch/kernel/hw_breakpoint.c
>
> diff --git a/arch/loongarch/Kconfig b/arch/loongarch/Kconfig
> index 54bd3dbde1f2..e3eba2eb4b44 100644
> --- a/arch/loongarch/Kconfig
> +++ b/arch/loongarch/Kconfig
> @@ -100,6 +100,7 @@ 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..44c109f0517f
> --- /dev/null
> +++ b/arch/loongarch/include/asm/hw_breakpoint.h
> @@ -0,0 +1,145 @@
> +/* 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 __reserved1 : 28,
> + len : 2,
> + type : 2;
> +};
> +
> +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_WATCH_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_WATCH_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)
> +
> +/* Exact number */
> +#define CSR_FWPC_NUM 0x3f
> +#define CSR_MWPC_NUM 0x3f
> +
> +static inline u32 encode_ctrl_reg(struct arch_hw_breakpoint_ctrl ctrl)
> +{
> + u32 val = (ctrl.len << 10) | (ctrl.type << 8);
> +
> + return val;
Just "return (ctrl.len << 10) | (ctrl.type << 8)".
And it is better to replace number with bits-macro.
> +}
> +
> +static inline void decode_ctrl_reg(u32 reg, struct arch_hw_breakpoint_ctrl *ctrl)
> +{
> + reg >>= 8;
> + ctrl->type = reg & 0x3;
> + reg >>= 2;
> + ctrl->len = reg & 0x3;
Use macro, too.
> +}
> +
> +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) & CSR_FWPC_NUM;
> + return ibcn;
"return csr_read64..." for clearity.
> +}
> +
> +/* Determine number of WRP registers available. */
> +static inline int get_num_wrps(void)
> +{
> + unsigned int dbcn;
> +
> + dbcn = csr_read64(LOONGARCH_CSR_MWPC) & CSR_MWPC_NUM;
> + return dbcn;
Ditto.
> +}
> +
> +#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..a62625af908b 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 +132,10 @@ 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];
> + unsigned long single_step;
As it is not used in this patch, should remove it?
> };
>
> #define thread_saved_ra(tsk) (tsk->thread.sched_ra)
> @@ -172,6 +177,8 @@ struct thread_struct {
> .fcc = 0, \
> .fpr = {{{0,},},}, \
> }, \
> + .hbp_break = {0}, \
> + .hbp_watch = {0}, \
So if not remove single_step, it mismatch here.
> }
>
> struct task_struct;
> @@ -184,10 +191,6 @@ 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..a98e1d212ba9 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); \
Redundant tab.
> (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 45c78aea63ce..006c892f9be3 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..509af6c54bed
> --- /dev/null
> +++ b/arch/loongarch/kernel/hw_breakpoint.c
> @@ -0,0 +1,517 @@
> +// 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_WATCH_READ(N, REG, T, VAL); \
> + break
> +
> +#define WRITE_WB_REG_CASE(OFF, N, REG, T, VAL) \
> + case (OFF + N): \
> + LOONGARCH_CSR_WATCH_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) {
Actually use slots[i] here also is OK, I think.
I means the slot is a redundant variable, but it depends on you.
> + *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;
> +
> + 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);
> + 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);
> + if (info->ctrl.type == LOONGARCH_BREAKPOINT_EXECUTE) {
> + write_wb_reg(CSR_CFG_CTRL, i, 0, 0x1e);
There should give many macros to avoid using imm directly.
> + } else {
> + ctrl = encode_ctrl_reg(info->ctrl);
> + write_wb_reg(CSR_CFG_CTRL, i, 1, ctrl | 0x1e | 1 << 8 | 1 << 9);
And here.
> + }
> + enable = csr_read64(LOONGARCH_CSR_CRMD);
> + csr_write64(1 << 9 | enable, LOONGARCH_CSR_CRMD);
And here.
> + 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)
> +{
> + 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;
> +}
How to following,
static int hbp_len[] = {
[LOONGARCH_BREAKPOINT_LEN_1] = 1,
[LOONGARCH_BREAKPOINT_LEN_2] = 2,
[LOONGARCH_BREAKPOINT_LEN_4] = 4,
[LOONGARCH_BREAKPOINT_LEN_8] = 8,
};
> +
> +/*
> + * 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);
> +}
> +
> +/*
> + * Extract generic type and length encodings from an arch_hw_breakpoint_ctrl.
> + * Hopefully this will disappear when ptrace can bypass the conversion
> + * to generic breakpoint descriptions.
> + */
> +int arch_bp_generic_fields(struct arch_hw_breakpoint_ctrl ctrl,
> + int *gen_len, int *gen_type, int *offset)
> +{
> + /* Type */
> + switch (ctrl.type) {
> + case LOONGARCH_BREAKPOINT_EXECUTE:
> + *gen_type = HW_BREAKPOINT_X;
> + break;
> + case LOONGARCH_BREAKPOINT_LOAD:
> + *gen_type = HW_BREAKPOINT_R;
> + break;
> + case LOONGARCH_BREAKPOINT_STORE:
> + *gen_type = HW_BREAKPOINT_W;
> + break;
> + case LOONGARCH_BREAKPOINT_LOAD | LOONGARCH_BREAKPOINT_STORE:
> + *gen_type = HW_BREAKPOINT_RW;
> + break;
> + default:
> + return -EINVAL;
> + }
> +
> + if (!ctrl.len)
> + return -EINVAL;
> + *offset = __ffs(ctrl.len);
> +
> + /* Len */
> + switch (ctrl.len) {
> + case LOONGARCH_BREAKPOINT_LEN_1:
> + *gen_len = HW_BREAKPOINT_LEN_1;
> + break;
> + case LOONGARCH_BREAKPOINT_LEN_2:
> + *gen_len = HW_BREAKPOINT_LEN_2;
> + break;
> + case LOONGARCH_BREAKPOINT_LEN_4:
> + *gen_len = HW_BREAKPOINT_LEN_4;
> + break;
> + case LOONGARCH_BREAKPOINT_LEN_8:
> + *gen_len = HW_BREAKPOINT_LEN_8;
> + break;
> + default:
> + return -EINVAL;
> + }
> +
> + return 0;
> +}
> +
> +/*
> + * 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;
> +}
> +
> +static void update_bp_registers(struct pt_regs *regs, int enable)
> +{
> + 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;
> +
Redundant line.
> + } 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;
> +
> + if (enable) {
> + if (csr_read64(LOONGARCH_CSR_MWPS) & 0xff) {
> + ctrl = read_wb_reg(CSR_CFG_CTRL, i, 1);
> + ctrl |= 0x1 << 8;
> + ctrl |= 0x1 << 9;
> + write_wb_reg(CSR_CFG_CTRL, i, 1, ctrl);
> + } else {
> + write_wb_reg(CSR_CFG_CTRL, i, 0, 0x1e);
> + write_wb_reg(CSR_CFG_CTRL, i, 0, 0x1e);
Macros and redundant tab.
> + }
> + regs->csr_prmd |= CSR_PRMD_PWE;
> + } else {
> + if (csr_read64(LOONGARCH_CSR_MWPS) & 0xff) {
> + ctrl = read_wb_reg(CSR_CFG_CTRL, i, 1);
> + ctrl = read_wb_reg(CSR_CFG_CTRL, i, 0);
> + ctrl &= ~0x1 << 8;
> + ctrl &= ~0x1 << 9;
> + write_wb_reg(CSR_CFG_CTRL, i, 1, ctrl);
> + } else {
> + write_wb_reg(CSR_CFG_CTRL, i, 0, 0);
> + }
> + regs->csr_prmd &= ~CSR_PRMD_PWE;
> + }
> + }
> +}
> +NOKPROBE_SYMBOL(update_bp_registers);
> +
> +/*
> + * Debug exception handlers.
> + */
> +int breakpoint_handler(struct pt_regs *regs)
> +{
> + int i;
> + 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 9073fab1a487..6b53781c0b59 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 +192,7 @@ 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 4aa3901c5623..70085d83476d 100644
> --- a/arch/loongarch/kernel/traps.c
> +++ b/arch/loongarch/kernel/traps.c
> @@ -508,7 +508,19 @@ 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;
The breakpoint_handler and watchpoint_handler seems always return 0.
As breakpoint_handler is invoked firstly, the logic, you select read
CSR.FWPS firstly, in update_bp_registers() is right. That means, if
you call watchpoint_handler() firstly when ex_watch is triggered by
breakpoint, then it invoke update_bp_registers, and last the condition
"csr_read64(LOONGARCH_CSR_FWPS) & 0xff" is true, error occurs.
Again, the current logic is right, but I think it is better to separate
the breakpoint and watchpoint case. You can try pass a new arg to
indicate it is breakpoint or watchpoint. Or separate it to two funcs.
And finnally, if breakpoint and watchpoint both triggered in same time,
does this patch handle right? Is One of them triggered or are both of
them triggered？
e.g.
0x10000: "li.d $rj, 0x100"
0x10004: "ld.d $rd, $rj, 0"
watch: 0x100, break: 0x10004
Thanks,
Jinyang
> +#endif
> + force_sig(SIGTRAP);
> + exception_exit(prev_state);
> + return;
> }
>
> asmlinkage void noinstr do_ri(struct pt_regs *regs)
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