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Message-ID: <CAAhV-H600pPCTEHzuMiiFRyKcgxq7ZGvaFMUv9pOeVE1xbYQ3A@mail.gmail.com>
Date: Tue, 13 Jun 2023 10:09:16 +0800
From: Huacai Chen <chenhuacai@...nel.org>
To: jianghaoran <jianghaoran@...inos.cn>
Cc: yangtiezhu@...ngson.cn, conor.dooley@...rochip.com,
hejinyang@...ngson.cn, jhrhhao@....com, kernel@...0n.name,
l3b2w1@...il.com, linux-kernel@...r.kernel.org,
loongarch@...ts.linux.dev, masahiroy@...nel.org,
mhiramat@...nel.org, palmer@...osinc.com, tangyouling@...ngson.cn,
zhangqing@...ngson.cn
Subject: Re: [PATCH v2] LoongArch/rethook: Replace kretprobe with rethook on loongarch
Hi, Haoran,
On Tue, Jun 13, 2023 at 9:20 AM jianghaoran <jianghaoran@...inos.cn> wrote:
>
> That's an adaptation of commit f3a112c0c40d ("x86,rethook,kprobes:
> Replace kretprobe with rethook on x86")and commit b57c2f124098
> ("riscv: add riscv rethook implementation") to loongarch.
> Mainly refer to this commit b57c2f124098.
>
> Replaces the kretprobe code with rethook on loongarch. With this patch,
> kretprobe on loongarch uses the rethook instead of kretprobe specific
> trampoline code.
Use LoongArch rather than loongarch in comments and commit messages.
>
> Signed-off-by: Haoran Jiang<jianghaoran@...inos.cn>
The format is Haoran Jiang <jianghaoran@...inos.cn>, pay attention to the space.
> ---
> v2:
> Modified the patch format and commit message.
> ---
> arch/loongarch/Kconfig | 1 +
> arch/loongarch/include/asm/kprobes.h | 3 ---
> arch/loongarch/kernel/Makefile | 3 ++-
> arch/loongarch/kernel/kprobes.c | 20 --------------
> arch/loongarch/kernel/rethook.c | 27 +++++++++++++++++++
> arch/loongarch/kernel/rethook.h | 8 ++++++
> ...obes_trampoline.S => rethook_trampoline.S} | 6 ++---
> 7 files changed, 41 insertions(+), 27 deletions(-)
> create mode 100644 arch/loongarch/kernel/rethook.c
> create mode 100644 arch/loongarch/kernel/rethook.h
> rename arch/loongarch/kernel/{kprobes_trampoline.S => rethook_trampoline.S} (93%)
>
> diff --git a/arch/loongarch/Kconfig b/arch/loongarch/Kconfig
> index d38b066fc931..33753a1ab0bb 100644
> --- a/arch/loongarch/Kconfig
> +++ b/arch/loongarch/Kconfig
> @@ -113,6 +113,7 @@ config LOONGARCH
> select HAVE_KPROBES
> select HAVE_KPROBES_ON_FTRACE
> select HAVE_KRETPROBES
> + select HAVE_RETHOOK
> select HAVE_MOD_ARCH_SPECIFIC
> select HAVE_NMI
> select HAVE_PCI
Use alpha-betical order for these symbols, though x86 and riscv don't
do this, s390 does.
> diff --git a/arch/loongarch/include/asm/kprobes.h b/arch/loongarch/include/asm/kprobes.h
> index 798020ae02c6..7b9fc3ed71c3 100644
> --- a/arch/loongarch/include/asm/kprobes.h
> +++ b/arch/loongarch/include/asm/kprobes.h
> @@ -49,9 +49,6 @@ bool kprobe_fault_handler(struct pt_regs *regs, int trapnr);
> bool kprobe_breakpoint_handler(struct pt_regs *regs);
> bool kprobe_singlestep_handler(struct pt_regs *regs);
>
> -void __kretprobe_trampoline(void);
> -void *trampoline_probe_handler(struct pt_regs *regs);
> -
> #else /* !CONFIG_KPROBES */
>
> static inline bool kprobe_breakpoint_handler(struct pt_regs *regs) { return false; }
> diff --git a/arch/loongarch/kernel/Makefile b/arch/loongarch/kernel/Makefile
> index 9a72d91cd104..e0d4d29a6f0f 100644
> --- a/arch/loongarch/kernel/Makefile
> +++ b/arch/loongarch/kernel/Makefile
> @@ -52,6 +52,7 @@ 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
> +obj-$(CONFIG_KPROBES) += kprobes.o
> +obj-$(CONFIG_RETHOOK) += rethook.o rethook_trampoline.o
>
> CPPFLAGS_vmlinux.lds := $(KBUILD_CFLAGS)
Please see commit 571a2a50a8fc546145ffd3bf673547e9 ("rethook, fprobe:
do not trace rethook related functions"), maybe we need to do some
additional modifications in Makefile.
> diff --git a/arch/loongarch/kernel/kprobes.c b/arch/loongarch/kernel/kprobes.c
> index 56c8c4b09a42..dbce23ba9970 100644
> --- a/arch/loongarch/kernel/kprobes.c
> +++ b/arch/loongarch/kernel/kprobes.c
> @@ -378,26 +378,6 @@ int __init arch_init_kprobes(void)
> return 0;
> }
>
> -/* ASM function that handles the kretprobes must not be probed */
> -NOKPROBE_SYMBOL(__kretprobe_trampoline);
> -
> -/* Called from __kretprobe_trampoline */
> -void __used *trampoline_probe_handler(struct pt_regs *regs)
> -{
> - return (void *)kretprobe_trampoline_handler(regs, NULL);
> -}
> -NOKPROBE_SYMBOL(trampoline_probe_handler);
> -
> -void arch_prepare_kretprobe(struct kretprobe_instance *ri,
> - struct pt_regs *regs)
> -{
> - ri->ret_addr = (kprobe_opcode_t *)regs->regs[1];
> - ri->fp = NULL;
> -
> - /* Replace the return addr with trampoline addr */
> - regs->regs[1] = (unsigned long)&__kretprobe_trampoline;
> -}
> -NOKPROBE_SYMBOL(arch_prepare_kretprobe);
>
> int arch_trampoline_kprobe(struct kprobe *p)
> {
> diff --git a/arch/loongarch/kernel/rethook.c b/arch/loongarch/kernel/rethook.c
> new file mode 100644
> index 000000000000..ac97b78daf55
> --- /dev/null
> +++ b/arch/loongarch/kernel/rethook.c
> @@ -0,0 +1,27 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Generic return hook for loongarch.
Use LoongArch here.
> + */
> +
> +#include <linux/kprobes.h>
> +#include <linux/rethook.h>
> +#include "rethook.h"
> +
> +/* This is called from arch_rethook_trampoline() */
> +unsigned long __used arch_rethook_trampoline_callback(struct pt_regs *regs)
> +{
> + return rethook_trampoline_handler(regs, 0);
> +}
> +
> +NOKPROBE_SYMBOL(arch_rethook_trampoline_callback);
> +
> +void arch_rethook_prepare(struct rethook_node *rhn, struct pt_regs *regs, bool mcount)
> +{
> + rhn->ret_addr = regs->regs[1];
> + rhn->frame = 0;
> +
> + /* replace return addr with trampoline */
> + regs->regs[1] = (unsigned long)arch_rethook_trampoline;
> +}
Whether the logic is correct here needs Tiezhu's review.
Thanks,
Huacai
> +
> +NOKPROBE_SYMBOL(arch_rethook_prepare);
> diff --git a/arch/loongarch/kernel/rethook.h b/arch/loongarch/kernel/rethook.h
> new file mode 100644
> index 000000000000..3f1c1edf0d0b
> --- /dev/null
> +++ b/arch/loongarch/kernel/rethook.h
> @@ -0,0 +1,8 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +#ifndef __LOONGARCH_RETHOOK_H
> +#define __LOONGARCH_RETHOOK_H
> +
> +unsigned long arch_rethook_trampoline_callback(struct pt_regs *regs);
> +void arch_rethook_prepare(struct rethook_node *rhn, struct pt_regs *regs, bool mcount);
> +
> +#endif
> diff --git a/arch/loongarch/kernel/kprobes_trampoline.S b/arch/loongarch/kernel/rethook_trampoline.S
> similarity index 93%
> rename from arch/loongarch/kernel/kprobes_trampoline.S
> rename to arch/loongarch/kernel/rethook_trampoline.S
> index af94b0d213fa..bd5772c96338 100644
> --- a/arch/loongarch/kernel/kprobes_trampoline.S
> +++ b/arch/loongarch/kernel/rethook_trampoline.S
> @@ -75,7 +75,7 @@
> csrxchg t0, t1, LOONGARCH_CSR_CRMD
> .endm
>
> -SYM_CODE_START(__kretprobe_trampoline)
> +SYM_CODE_START(arch_rethook_trampoline)
> addi.d sp, sp, -PT_SIZE
> save_all_base_regs
>
> @@ -84,7 +84,7 @@ SYM_CODE_START(__kretprobe_trampoline)
>
> move a0, sp /* pt_regs */
>
> - bl trampoline_probe_handler
> + bl arch_rethook_trampoline_callback
>
> /* use the result as the return-address */
> move ra, a0
> @@ -93,4 +93,4 @@ SYM_CODE_START(__kretprobe_trampoline)
> addi.d sp, sp, PT_SIZE
>
> jr ra
> -SYM_CODE_END(__kretprobe_trampoline)
> +SYM_CODE_END(arch_rethook_trampoline)
> --
> 2.27.0
>
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