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Win64; x64; rv:102.0) Gecko/20100101 Thunderbird/102.2.0 Subject: Re: [PATCH v3 1/3] entry: Add some arch funcs to support arm64 to use generic entry Content-Language: en-US To: Kevin Brodsky CC: , , , , , , , , , , , , , , , , References: <20240629085601.470241-1-ruanjinjie@huawei.com> <20240629085601.470241-2-ruanjinjie@huawei.com> <1ce09739-14a4-42a2-b5c9-66fdc72ae999@arm.com> From: Jinjie Ruan In-Reply-To: <1ce09739-14a4-42a2-b5c9-66fdc72ae999@arm.com> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.67.109.254] X-ClientProxiedBy: dggems701-chm.china.huawei.com (10.3.19.178) To kwepemh500013.china.huawei.com (7.202.181.146) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240822_053638_569286_792957FB X-CRM114-Status: GOOD ( 25.19 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 2024/8/20 19:41, Kevin Brodsky wrote: > On 29/06/2024 10:55, Jinjie Ruan wrote: >> Add some arch functions to support arm64 to use generic entry, which do not >> affect existing architectures that use generic entry: >> >> - arch_prepare/post_report_syscall_entry/exit(). >> >> - arch_enter_from_kernel_mode(), arch_exit_to_kernel_mode_prepare(). >> >> - arch_irqentry_exit_need_resched() to support architecture-related >> need_resched() check logic. >> >> Also make syscall_exit_work() not static and move report_single_step() to >> thread_info.h, which can be used by arm64 later. >> >> x86 and Riscv compilation test ok after this patch. >> >> Signed-off-by: Jinjie Ruan >> Suggested-by: Thomas Gleixner >> --- >> v3: >> - Make the arch funcs not use __weak as Thomas suggested. >> - Make arch_forget_syscall() folded in arch_post_report_syscall_entry(). >> - __always_inline -> inline. >> - Move report_single_step() to thread_info.h for arm64 >> - Add Suggested-by. >> - Update the commit message. >> >> v2: >> - Fix a bug that not call arch_post_report_syscall_entry() in >> syscall_trace_enter() if ptrace_report_syscall_entry() return not zero. >> - Update the commit message. >> --- >> include/linux/entry-common.h | 90 ++++++++++++++++++++++++++++++++++++ >> include/linux/thread_info.h | 13 ++++++ >> kernel/entry/common.c | 37 +++++++-------- >> 3 files changed, 122 insertions(+), 18 deletions(-) >> >> diff --git a/include/linux/entry-common.h b/include/linux/entry-common.h >> index b0fb775a600d..2aea23ca9d66 100644 >> --- a/include/linux/entry-common.h >> +++ b/include/linux/entry-common.h >> @@ -290,6 +290,94 @@ static __always_inline void arch_exit_to_user_mode(void); >> static __always_inline void arch_exit_to_user_mode(void) { } >> #endif >> >> +/** >> + * arch_enter_from_kernel_mode - Architecture specific check work. > > Maybe those comments could be expanded to be closer to the existing > ones, like arch_enter_from_user_mode()? It would help if they were more > specific as to where they are called (especially the *report_syscall* > ones) and how they are expected to be used. You are right! It needed to be expanded. > >> + */ >> +static inline void arch_enter_from_kernel_mode(struct pt_regs *regs); >> + >> +#ifndef arch_enter_from_kernel_mode >> +static inline void arch_enter_from_kernel_mode(struct pt_regs *regs) { } >> +#endif >> + >> +/** >> + * arch_exit_to_kernel_mode_prepare - Architecture specific final work before >> + * exit to kernel mode. >> + */ >> +static inline void arch_exit_to_kernel_mode_prepare(struct pt_regs *regs); > > Any reason to suffix this function with "prepare"? Just > arch_exit_to_kernel_mode() seems appropriate (symmetric with > arch_enter_from_kernel_mode()). prepare means it is the first function before all other exit_to_kernel operation in irqentry_exit(), but as the order problem, it can be adjusted to the last to aligh with the older arm64 version. > >> + >> +#ifndef arch_exit_to_kernel_mode_prepare >> +static inline void arch_exit_to_kernel_mode_prepare(struct pt_regs *regs) { } >> +#endif >> + >> +/** >> + * arch_prepare_report_syscall_entry - Architecture specific work before >> + * report_syscall_entry(). >> + */ >> +static inline unsigned long arch_prepare_report_syscall_entry(struct pt_regs *regs); > > The most common naming patterns for such arch helper pairs seems to be > pre/post, so maybe arch_pre_report_syscall_entry()? Right! > >> + >> +#ifndef arch_prepare_report_syscall_entry >> +static inline unsigned long arch_prepare_report_syscall_entry(struct pt_regs *regs) >> +{ >> + return 0; >> +} >> +#endif >> + >> +/** >> + * arch_post_report_syscall_entry - Architecture specific work after >> + * report_syscall_entry(). >> + */ >> +static inline void arch_post_report_syscall_entry(struct pt_regs *regs, >> + unsigned long saved_reg, >> + long ret); >> + >> +#ifndef arch_post_report_syscall_entry >> +static inline void arch_post_report_syscall_entry(struct pt_regs *regs, >> + unsigned long saved_reg, >> + long ret) >> +{ >> +} >> +#endif >> + >> +/** >> + * arch_prepare_report_syscall_exit - Architecture specific work before >> + * report_syscall_exit(). >> + */ >> +static inline unsigned long arch_prepare_report_syscall_exit(struct pt_regs *regs, >> + unsigned long work); >> + >> +#ifndef arch_prepare_report_syscall_exit >> +static inline unsigned long arch_prepare_report_syscall_exit(struct pt_regs *regs, >> + unsigned long work) >> +{ >> + return 0; >> +} >> +#endif >> + >> +/** >> + * arch_post_report_syscall_exit - Architecture specific work after >> + * report_syscall_exit(). >> + */ >> +static inline void arch_post_report_syscall_exit(struct pt_regs *regs, >> + unsigned long saved_reg, >> + unsigned long work); >> + >> +#ifndef arch_post_report_syscall_exit >> +static inline void arch_post_report_syscall_exit(struct pt_regs *regs, >> + unsigned long saved_reg, >> + unsigned long work) >> +{ >> +} >> +#endif >> + >> +/** >> + * arch_irqentry_exit_need_resched - Architecture specific need resched function >> + */ >> +static inline bool arch_irqentry_exit_need_resched(void); >> + >> +#ifndef arch_irqentry_exit_need_resched >> +static inline bool arch_irqentry_exit_need_resched(void) { return true; } >> +#endif > > Nit: the existing arch_* hooks seem to be declared close to the function > they are called from (e.g. arch_enter_from_user_mode() just before > enter_from_user_mode()), maybe we could do the same with those new > hooks, where possible. Yes, do the same with those new hooks will be nice. > >> + >> /** >> * arch_do_signal_or_restart - Architecture specific signal delivery function >> * @regs: Pointer to currents pt_regs >> @@ -552,4 +640,6 @@ irqentry_state_t noinstr irqentry_nmi_enter(struct pt_regs *regs); >> */ >> void noinstr irqentry_nmi_exit(struct pt_regs *regs, irqentry_state_t irq_state); >> >> +void syscall_exit_work(struct pt_regs *regs, unsigned long work); >> + >> #endif >> diff --git a/include/linux/thread_info.h b/include/linux/thread_info.h >> index 9ea0b28068f4..062de9666ef3 100644 >> --- a/include/linux/thread_info.h >> +++ b/include/linux/thread_info.h >> @@ -55,6 +55,19 @@ enum syscall_work_bit { >> #define SYSCALL_WORK_SYSCALL_AUDIT BIT(SYSCALL_WORK_BIT_SYSCALL_AUDIT) >> #define SYSCALL_WORK_SYSCALL_USER_DISPATCH BIT(SYSCALL_WORK_BIT_SYSCALL_USER_DISPATCH) >> #define SYSCALL_WORK_SYSCALL_EXIT_TRAP BIT(SYSCALL_WORK_BIT_SYSCALL_EXIT_TRAP) >> + >> +/* >> + * If SYSCALL_EMU is set, then the only reason to report is when >> + * SINGLESTEP is set (i.e. PTRACE_SYSEMU_SINGLESTEP). This syscall >> + * instruction has been already reported in syscall_enter_from_user_mode(). >> + */ >> +static inline bool report_single_step(unsigned long work) >> +{ >> + if (work & SYSCALL_WORK_SYSCALL_EMU) >> + return false; >> + >> + return work & SYSCALL_WORK_SYSCALL_EXIT_TRAP; >> +} >> #endif >> >> #include >> diff --git a/kernel/entry/common.c b/kernel/entry/common.c >> index 90843cc38588..cd76391ffcb9 100644 >> --- a/kernel/entry/common.c >> +++ b/kernel/entry/common.c >> @@ -28,6 +28,7 @@ static inline void syscall_enter_audit(struct pt_regs *regs, long syscall) >> long syscall_trace_enter(struct pt_regs *regs, long syscall, >> unsigned long work) >> { >> + unsigned long saved_reg; > > Nit: could be declared inside the if block. Right! > > Kevin > >> long ret = 0; >> >> /* >> @@ -42,8 +43,10 @@ long syscall_trace_enter(struct pt_regs *regs, long syscall, >> >> /* Handle ptrace */ >> if (work & (SYSCALL_WORK_SYSCALL_TRACE | SYSCALL_WORK_SYSCALL_EMU)) { >> + saved_reg = arch_prepare_report_syscall_entry(regs); >> ret = ptrace_report_syscall_entry(regs); >> - if (ret || (work & SYSCALL_WORK_SYSCALL_EMU)) >> + arch_post_report_syscall_entry(regs, saved_reg, ret); >> + if (ret || work & SYSCALL_WORK_SYSCALL_EMU) >> return -1L; >> } >> >> [...] >