[PATCH v6 00/10] arm64: entry: Convert to generic irq entry
Currently, x86, Riscv, Loongarch use the generic entry which makes maintainers' work easier and codes more elegant. In the previous patchset, arm64 has already successfully switched to the generic IRQ entry, it is time to completely convert arm64 to generic entry. The main convert steps are as follows: - Make arm64 closer to generic syscall entry code. - Switch to generic entry. This patch set is rebased on v6.17-rc1. It was tested ok with following test cases on QEMU virt platform: - Perf tests. - Different `dynamic preempt` mode switch. - Pseudo NMI tests. - Stress-ng CPU stress test. - MTE test case in Documentation/arch/arm64/memory-tagging-extension.rst and all test cases in tools/testing/selftests/arm64/mte/*. The test QEMU configuration is as follows: qemu-system-aarch64 \ -M virt,gic-version=3,virtualization=on,mte=on \ -cpu max,pauth-impdef=on \ -kernel Image \ -smp 8,sockets=1,cores=4,threads=2 \ -m 512m \ -nographic \ -no-reboot \ -device virtio-rng-pci \ -append "root=/dev/vda rw console=ttyAMA0 kgdboc=ttyAMA0,115200 \ earlycon preempt=voluntary irqchip.gicv3_pseudo_nmi=1" \ -drive if=none,file=images/rootfs.ext4,format=raw,id=hd0 \ -device virtio-blk-device,drive=hd0 \ Changes in v6: - Rebased on 6.14 rc2 next. - Put the irq entry bits aside and split it out. - Update the commit message. - Link to v5: https://lore.kernel.org/all/20241206101744.4161990-1-ruanjinjie@huawei.com/ Changes in v5: - Not change arm32 and keep inerrupts_enabled() macro for gicv3 driver. - Move irqentry_state definition into arch/arm64/kernel/entry-common.c. - Avoid removing the __enter_from_*() and __exit_to_*() wrappers. - Update "irqentry_state_t ret/irq_state" to "state" to keep it consistently. - Use generic irq entry header for PREEMPT_DYNAMIC after split the generic entry. - Also refactor the ARM64 syscall code. - Introduce arch_ptrace_report_syscall_entry/exit(), instead of arch_pre/post_report_syscall_entry/exit() to simplify code. - Make the syscall patches clear separation. - Update the commit message. - Link to v4: https://lore.kernel.org/all/20241025100700.3714552-1-ruanjinjie@huawei.com/ Changes in v4: - Rework/cleanup split into a few patches as Mark suggested. - Replace interrupts_enabled() macro with regs_irqs_disabled(), instead of left it here. - Remove rcu and lockdep state in pt_regs by using temporary irqentry_state_t as Mark suggested. - Remove some unnecessary intermediate functions to make it clear. - Rework preempt irq and PREEMPT_DYNAMIC code to make the switch more clear. - arch_prepare_*_entry/exit() -> arch_pre_*_entry/exit(). - Expand the arch functions comment. - Make arch functions closer to its caller. - Declare saved_reg in for block. - Remove arch_exit_to_kernel_mode_prepare(), arch_enter_from_kernel_mode(). - Adjust "Add few arch functions to use generic entry" patch to be the penultimate. - Update the commit message. - Add suggested-by. - Link to v3: https://lore.kernel.org/all/20240629085601.470241-1-ruanjinjie@huawei.com/ Changes in v3: - Test the MTE test cases. - Handle forget_syscall() in arch_post_report_syscall_entry() - Make the arch funcs not use __weak as Thomas suggested, so move the arch funcs to entry-common.h, and make arch_forget_syscall() folded in arch_post_report_syscall_entry() as suggested. - Move report_single_step() to thread_info.h for arm64 - Change __always_inline() to inline, add inline for the other arch funcs. - Remove unused signal.h for entry-common.h. - Add Suggested-by. - Update the commit message. Changes in v2: - Add tested-by. - Fix a bug that not call arch_post_report_syscall_entry() in syscall_trace_enter() if ptrace_report_syscall_entry() return not zero. - Refactor report_syscall(). - Add comment for arch_prepare_report_syscall_exit(). - Adjust entry-common.h header file inclusion to alphabetical order. - Update the commit message. Jinjie Ruan (10): arm64/ptrace: Split report_syscall() arm64/ptrace: Refactor syscall_trace_enter/exit() arm64/ptrace: Refator el0_svc_common() entry: Add syscall_exit_to_user_mode_prepare() helper arm64/ptrace: Handle ptrace_report_syscall_entry() error arm64/ptrace: Expand secure_computing() in place arm64/ptrace: Use syscall_get_arguments() heleper entry: Add arch_ptrace_report_syscall_entry/exit() entry: Add has_syscall_work() helper arm64: entry: Convert to generic entry arch/arm64/Kconfig | 2 +- arch/arm64/include/asm/entry-common.h | 69 ++++++++++++++++++++ arch/arm64/include/asm/syscall.h | 6 +- arch/arm64/include/asm/thread_info.h | 22 +------ arch/arm64/kernel/debug-monitors.c | 7 +++ arch/arm64/kernel/ptrace.c | 90 --------------------------- arch/arm64/kernel/signal.c | 2 +- arch/arm64/kernel/syscall.c | 31 +++------ include/linux/entry-common.h | 42 ++++++++----- kernel/entry/syscall-common.c | 43 ++++++++++++- 10 files changed, 161 insertions(+), 153 deletions(-) -- 2.34.1
The generic syscall entry code has the form: | syscall_trace_enter() | { | ptrace_report_syscall_entry() | } | | syscall_exit_work() | { | ptrace_report_syscall_exit() | } In preparation for moving arm64 over to the generic entry code, split report_syscall() to two separate enter and exit functions to align the structure of the arm64 code with syscall_trace_enter() and syscall_exit_work() from the generic entry code. No functional changes. Suggested-by: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Jinjie Ruan <ruanjinjie@huawei.com> --- arch/arm64/kernel/ptrace.c | 29 ++++++++++++++++++++--------- 1 file changed, 20 insertions(+), 9 deletions(-) diff --git a/arch/arm64/kernel/ptrace.c b/arch/arm64/kernel/ptrace.c index 4b001121c72d..5534c175ceb7 100644 --- a/arch/arm64/kernel/ptrace.c +++ b/arch/arm64/kernel/ptrace.c @@ -2317,7 +2317,7 @@ enum ptrace_syscall_dir { PTRACE_SYSCALL_EXIT, }; -static void report_syscall(struct pt_regs *regs, enum ptrace_syscall_dir dir) +static void report_syscall_enter(struct pt_regs *regs) { int regno; unsigned long saved_reg; @@ -2340,13 +2340,24 @@ static void report_syscall(struct pt_regs *regs, enum ptrace_syscall_dir dir) */ regno = (is_compat_task() ? 12 : 7); saved_reg = regs->regs[regno]; - regs->regs[regno] = dir; + regs->regs[regno] = PTRACE_SYSCALL_ENTER; - if (dir == PTRACE_SYSCALL_ENTER) { - if (ptrace_report_syscall_entry(regs)) - forget_syscall(regs); - regs->regs[regno] = saved_reg; - } else if (!test_thread_flag(TIF_SINGLESTEP)) { + if (ptrace_report_syscall_entry(regs)) + forget_syscall(regs); + regs->regs[regno] = saved_reg; +} + +static void report_syscall_exit(struct pt_regs *regs) +{ + int regno; + unsigned long saved_reg; + + /* See comment for report_syscall_enter() above */ + regno = (is_compat_task() ? 12 : 7); + saved_reg = regs->regs[regno]; + regs->regs[regno] = PTRACE_SYSCALL_EXIT; + + if (!test_thread_flag(TIF_SINGLESTEP)) { ptrace_report_syscall_exit(regs, 0); regs->regs[regno] = saved_reg; } else { @@ -2366,7 +2377,7 @@ int syscall_trace_enter(struct pt_regs *regs) unsigned long flags = read_thread_flags(); if (flags & (_TIF_SYSCALL_EMU | _TIF_SYSCALL_TRACE)) { - report_syscall(regs, PTRACE_SYSCALL_ENTER); + report_syscall_enter(regs); if (flags & _TIF_SYSCALL_EMU) return NO_SYSCALL; } @@ -2394,7 +2405,7 @@ void syscall_trace_exit(struct pt_regs *regs) trace_sys_exit(regs, syscall_get_return_value(current, regs)); if (flags & (_TIF_SYSCALL_TRACE | _TIF_SINGLESTEP)) - report_syscall(regs, PTRACE_SYSCALL_EXIT); + report_syscall_exit(regs); rseq_syscall(regs); } -- 2.34.1
The generic syscall entry code has the following form, which use the input syscall work flag and syscall number: | syscall_trace_enter(struct pt_regs *regs, long syscall, | unsigned long work) | | syscall_exit_work(struct pt_regs *regs, unsigned long work) In preparation for moving arm64 over to the generic entry code, refactor syscall_trace_enter/exit() to also pass thread flags, and get syscall number by syscall_get_nr() helper. No functional changes. Signed-off-by: Jinjie Ruan <ruanjinjie@huawei.com> --- arch/arm64/include/asm/syscall.h | 4 ++-- arch/arm64/kernel/ptrace.c | 24 +++++++++++++++--------- arch/arm64/kernel/syscall.c | 5 +++-- 3 files changed, 20 insertions(+), 13 deletions(-) diff --git a/arch/arm64/include/asm/syscall.h b/arch/arm64/include/asm/syscall.h index 712daa90e643..d69f590a989b 100644 --- a/arch/arm64/include/asm/syscall.h +++ b/arch/arm64/include/asm/syscall.h @@ -114,7 +114,7 @@ static inline int syscall_get_arch(struct task_struct *task) return AUDIT_ARCH_AARCH64; } -int syscall_trace_enter(struct pt_regs *regs); -void syscall_trace_exit(struct pt_regs *regs); +int syscall_trace_enter(struct pt_regs *regs, long syscall, unsigned long flags); +void syscall_trace_exit(struct pt_regs *regs, unsigned long flags); #endif /* __ASM_SYSCALL_H */ diff --git a/arch/arm64/kernel/ptrace.c b/arch/arm64/kernel/ptrace.c index 5534c175ceb7..bbb868f6b292 100644 --- a/arch/arm64/kernel/ptrace.c +++ b/arch/arm64/kernel/ptrace.c @@ -2372,10 +2372,8 @@ static void report_syscall_exit(struct pt_regs *regs) } } -int syscall_trace_enter(struct pt_regs *regs) +int syscall_trace_enter(struct pt_regs *regs, long syscall, unsigned long flags) { - unsigned long flags = read_thread_flags(); - if (flags & (_TIF_SYSCALL_EMU | _TIF_SYSCALL_TRACE)) { report_syscall_enter(regs); if (flags & _TIF_SYSCALL_EMU) @@ -2386,19 +2384,27 @@ int syscall_trace_enter(struct pt_regs *regs) if (secure_computing() == -1) return NO_SYSCALL; - if (test_thread_flag(TIF_SYSCALL_TRACEPOINT)) - trace_sys_enter(regs, regs->syscallno); + /* Either of the above might have changed the syscall number */ + syscall = syscall_get_nr(current, regs); + + if (test_thread_flag(TIF_SYSCALL_TRACEPOINT)) { + trace_sys_enter(regs, syscall); - audit_syscall_entry(regs->syscallno, regs->orig_x0, regs->regs[1], + /* + * Probes or BPF hooks in the tracepoint may have changed the + * system call number as well. + */ + syscall = syscall_get_nr(current, regs); + } + + audit_syscall_entry(syscall, regs->orig_x0, regs->regs[1], regs->regs[2], regs->regs[3]); return regs->syscallno; } -void syscall_trace_exit(struct pt_regs *regs) +void syscall_trace_exit(struct pt_regs *regs, unsigned long flags) { - unsigned long flags = read_thread_flags(); - audit_syscall_exit(regs); if (flags & _TIF_SYSCALL_TRACEPOINT) diff --git a/arch/arm64/kernel/syscall.c b/arch/arm64/kernel/syscall.c index c442fcec6b9e..064dc114fb9b 100644 --- a/arch/arm64/kernel/syscall.c +++ b/arch/arm64/kernel/syscall.c @@ -124,7 +124,7 @@ static void el0_svc_common(struct pt_regs *regs, int scno, int sc_nr, */ if (scno == NO_SYSCALL) syscall_set_return_value(current, regs, -ENOSYS, 0); - scno = syscall_trace_enter(regs); + scno = syscall_trace_enter(regs, regs->syscallno, flags); if (scno == NO_SYSCALL) goto trace_exit; } @@ -143,7 +143,8 @@ static void el0_svc_common(struct pt_regs *regs, int scno, int sc_nr, } trace_exit: - syscall_trace_exit(regs); + flags = read_thread_flags(); + syscall_trace_exit(regs, flags); } void do_el0_svc(struct pt_regs *regs) -- 2.34.1
Compared to the generic entry code, arm64 terminate the process after report_syscall_exit() if the syscall is issued within a restartable sequence. In preparation for moving arm64 over to the generic entry code, refactor el0_svc_common() as below: - Extract syscall_exit_to_user_mode_prepare() to replace the the combination of read_thread_flags() and syscall_trace_exit(), also move the syscall exit check logic into it. - Move rseq_syscall() ahead, so the CONFIG_DEBUG_RSEQ check is not needed. - Move has_syscall_work() helper into asm/syscall.h, which will be reused by ptrace.c. Signed-off-by: Jinjie Ruan <ruanjinjie@huawei.com> --- arch/arm64/include/asm/syscall.h | 7 ++++++- arch/arm64/kernel/ptrace.c | 10 +++++++++- arch/arm64/kernel/syscall.c | 26 +++++--------------------- 3 files changed, 20 insertions(+), 23 deletions(-) diff --git a/arch/arm64/include/asm/syscall.h b/arch/arm64/include/asm/syscall.h index d69f590a989b..6225981fbbdb 100644 --- a/arch/arm64/include/asm/syscall.h +++ b/arch/arm64/include/asm/syscall.h @@ -114,7 +114,12 @@ static inline int syscall_get_arch(struct task_struct *task) return AUDIT_ARCH_AARCH64; } +static inline bool has_syscall_work(unsigned long flags) +{ + return unlikely(flags & _TIF_SYSCALL_WORK); +} + int syscall_trace_enter(struct pt_regs *regs, long syscall, unsigned long flags); -void syscall_trace_exit(struct pt_regs *regs, unsigned long flags); +void syscall_exit_to_user_mode_prepare(struct pt_regs *regs); #endif /* __ASM_SYSCALL_H */ diff --git a/arch/arm64/kernel/ptrace.c b/arch/arm64/kernel/ptrace.c index bbb868f6b292..95984bbf53db 100644 --- a/arch/arm64/kernel/ptrace.c +++ b/arch/arm64/kernel/ptrace.c @@ -2403,7 +2403,7 @@ int syscall_trace_enter(struct pt_regs *regs, long syscall, unsigned long flags) return regs->syscallno; } -void syscall_trace_exit(struct pt_regs *regs, unsigned long flags) +static void syscall_trace_exit(struct pt_regs *regs, unsigned long flags) { audit_syscall_exit(regs); @@ -2412,8 +2412,16 @@ void syscall_trace_exit(struct pt_regs *regs, unsigned long flags) if (flags & (_TIF_SYSCALL_TRACE | _TIF_SINGLESTEP)) report_syscall_exit(regs); +} + +void syscall_exit_to_user_mode_prepare(struct pt_regs *regs) +{ + unsigned long flags = read_thread_flags(); rseq_syscall(regs); + + if (has_syscall_work(flags) || flags & _TIF_SINGLESTEP) + syscall_trace_exit(regs, flags); } /* diff --git a/arch/arm64/kernel/syscall.c b/arch/arm64/kernel/syscall.c index 064dc114fb9b..a50db885fc34 100644 --- a/arch/arm64/kernel/syscall.c +++ b/arch/arm64/kernel/syscall.c @@ -65,11 +65,6 @@ static void invoke_syscall(struct pt_regs *regs, unsigned int scno, choose_random_kstack_offset(get_random_u16()); } -static inline bool has_syscall_work(unsigned long flags) -{ - return unlikely(flags & _TIF_SYSCALL_WORK); -} - static void el0_svc_common(struct pt_regs *regs, int scno, int sc_nr, const syscall_fn_t syscall_table[]) { @@ -125,26 +120,15 @@ static void el0_svc_common(struct pt_regs *regs, int scno, int sc_nr, if (scno == NO_SYSCALL) syscall_set_return_value(current, regs, -ENOSYS, 0); scno = syscall_trace_enter(regs, regs->syscallno, flags); - if (scno == NO_SYSCALL) - goto trace_exit; + if (scno == NO_SYSCALL) { + syscall_exit_to_user_mode_prepare(regs); + return; + } } invoke_syscall(regs, scno, sc_nr, syscall_table); - /* - * The tracing status may have changed under our feet, so we have to - * check again. However, if we were tracing entry, then we always trace - * exit regardless, as the old entry assembly did. - */ - if (!has_syscall_work(flags) && !IS_ENABLED(CONFIG_DEBUG_RSEQ)) { - flags = read_thread_flags(); - if (!has_syscall_work(flags) && !(flags & _TIF_SINGLESTEP)) - return; - } - -trace_exit: - flags = read_thread_flags(); - syscall_trace_exit(regs, flags); + syscall_exit_to_user_mode_prepare(regs); } void do_el0_svc(struct pt_regs *regs) -- 2.34.1
In the generic entry code, the part before syscall_exit_to_user_mode_work() calls syscall_exit_work(), which serves the same purpose as syscall_exit_to_user_mode_prepare() in arm64. In preparation for moving arm64 over to the generic entry code, extract syscall_exit_to_user_mode_prepare() helper from syscall_exit_to_user_mode_work(). No functional changes. Signed-off-by: Jinjie Ruan <ruanjinjie@huawei.com> --- include/linux/entry-common.h | 35 ++++++++++++++++++++++------------- 1 file changed, 22 insertions(+), 13 deletions(-) diff --git a/include/linux/entry-common.h b/include/linux/entry-common.h index 7177436f0f9e..cd6dacb2d8bf 100644 --- a/include/linux/entry-common.h +++ b/include/linux/entry-common.h @@ -137,20 +137,11 @@ static __always_inline long syscall_enter_from_user_mode(struct pt_regs *regs, l */ void syscall_exit_work(struct pt_regs *regs, unsigned long work); -/** - * syscall_exit_to_user_mode_work - Handle work before returning to user mode - * @regs: Pointer to currents pt_regs - * - * Same as step 1 and 2 of syscall_exit_to_user_mode() but without calling - * exit_to_user_mode() to perform the final transition to user mode. - * - * Calling convention is the same as for syscall_exit_to_user_mode() and it - * returns with all work handled and interrupts disabled. The caller must - * invoke exit_to_user_mode() before actually switching to user mode to - * make the final state transitions. Interrupts must stay disabled between - * return from this function and the invocation of exit_to_user_mode(). +/* + * Syscall specific exit to user mode preparation. Runs with interrupts + * enabled. */ -static __always_inline void syscall_exit_to_user_mode_work(struct pt_regs *regs) +static __always_inline void syscall_exit_to_user_mode_prepare(struct pt_regs *regs) { unsigned long work = READ_ONCE(current_thread_info()->syscall_work); unsigned long nr = syscall_get_nr(current, regs); @@ -171,6 +162,24 @@ static __always_inline void syscall_exit_to_user_mode_work(struct pt_regs *regs) */ if (unlikely(work & SYSCALL_WORK_EXIT)) syscall_exit_work(regs, work); +} + +/** + * syscall_exit_to_user_mode_work - Handle work before returning to user mode + * @regs: Pointer to currents pt_regs + * + * Same as step 1 and 2 of syscall_exit_to_user_mode() but without calling + * exit_to_user_mode() to perform the final transition to user mode. + * + * Calling convention is the same as for syscall_exit_to_user_mode() and it + * returns with all work handled and interrupts disabled. The caller must + * invoke exit_to_user_mode() before actually switching to user mode to + * make the final state transitions. Interrupts must stay disabled between + * return from this function and the invocation of exit_to_user_mode(). + */ +static __always_inline void syscall_exit_to_user_mode_work(struct pt_regs *regs) +{ + syscall_exit_to_user_mode_prepare(regs); local_irq_disable_exit_to_user(); exit_to_user_mode_prepare(regs); } -- 2.34.1
The generic entry handle error of ptrace_report_syscall_entry(), but arm64 not. As the comment said, the calling arch code should abort the system call and must prevent normal entry so no system call is made if ptrace_report_syscall_entry() return nonzero. In preparation for moving arm64 over to the generic entry code, return early if ptrace_report_syscall_entry() encounters an error. Signed-off-by: Jinjie Ruan <ruanjinjie@huawei.com> --- arch/arm64/kernel/ptrace.c | 16 +++++++++++----- 1 file changed, 11 insertions(+), 5 deletions(-) diff --git a/arch/arm64/kernel/ptrace.c b/arch/arm64/kernel/ptrace.c index 95984bbf53db..707951ad5d24 100644 --- a/arch/arm64/kernel/ptrace.c +++ b/arch/arm64/kernel/ptrace.c @@ -2317,10 +2317,10 @@ enum ptrace_syscall_dir { PTRACE_SYSCALL_EXIT, }; -static void report_syscall_enter(struct pt_regs *regs) +static int report_syscall_enter(struct pt_regs *regs) { - int regno; unsigned long saved_reg; + int regno, ret; /* * We have some ABI weirdness here in the way that we handle syscall @@ -2342,9 +2342,13 @@ static void report_syscall_enter(struct pt_regs *regs) saved_reg = regs->regs[regno]; regs->regs[regno] = PTRACE_SYSCALL_ENTER; - if (ptrace_report_syscall_entry(regs)) + ret = ptrace_report_syscall_entry(regs); + if (ret) forget_syscall(regs); + regs->regs[regno] = saved_reg; + + return ret; } static void report_syscall_exit(struct pt_regs *regs) @@ -2374,9 +2378,11 @@ static void report_syscall_exit(struct pt_regs *regs) int syscall_trace_enter(struct pt_regs *regs, long syscall, unsigned long flags) { + int ret; + if (flags & (_TIF_SYSCALL_EMU | _TIF_SYSCALL_TRACE)) { - report_syscall_enter(regs); - if (flags & _TIF_SYSCALL_EMU) + ret = report_syscall_enter(regs); + if (ret || (flags & _TIF_SYSCALL_EMU)) return NO_SYSCALL; } -- 2.34.1
The generic entry expand secure_computing() in place and call __secure_computing() directly. In order to switch to the generic entry for arm64, refactor secure_computing() for syscall_trace_enter(). No functional changes. Signed-off-by: Jinjie Ruan <ruanjinjie@huawei.com> --- arch/arm64/kernel/ptrace.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/arch/arm64/kernel/ptrace.c b/arch/arm64/kernel/ptrace.c index 707951ad5d24..9af3046a2ce9 100644 --- a/arch/arm64/kernel/ptrace.c +++ b/arch/arm64/kernel/ptrace.c @@ -2387,8 +2387,11 @@ int syscall_trace_enter(struct pt_regs *regs, long syscall, unsigned long flags) } /* Do the secure computing after ptrace; failures should be fast. */ - if (secure_computing() == -1) - return NO_SYSCALL; + if (flags & _TIF_SECCOMP) { + ret = __secure_computing(NULL); + if (ret == -1L) + return NO_SYSCALL; + } /* Either of the above might have changed the syscall number */ syscall = syscall_get_nr(current, regs); -- 2.34.1
The generic entry check audit context first and use syscall_get_arguments() helper. In order to switch to the generic entry for arm64, - Also use the helper. - Extract the syscall_enter_audit() helper to make it clear. - Check audit context for syscall_enter_audit(), which only adds one additional check without any other differences as audit_syscall_entry() check it first otherwise do nothing. No functional changes. Signed-off-by: Jinjie Ruan <ruanjinjie@huawei.com> --- arch/arm64/kernel/ptrace.c | 14 ++++++++++++-- 1 file changed, 12 insertions(+), 2 deletions(-) diff --git a/arch/arm64/kernel/ptrace.c b/arch/arm64/kernel/ptrace.c index 9af3046a2ce9..9455ccf1ecc1 100644 --- a/arch/arm64/kernel/ptrace.c +++ b/arch/arm64/kernel/ptrace.c @@ -2376,6 +2376,17 @@ static void report_syscall_exit(struct pt_regs *regs) } } +static inline void syscall_enter_audit(struct pt_regs *regs, long syscall) +{ + if (unlikely(audit_context())) { + unsigned long args[6]; + + syscall_get_arguments(current, regs, args); + audit_syscall_entry(syscall, args[0], args[1], args[2], args[3]); + } + +} + int syscall_trace_enter(struct pt_regs *regs, long syscall, unsigned long flags) { int ret; @@ -2406,8 +2417,7 @@ int syscall_trace_enter(struct pt_regs *regs, long syscall, unsigned long flags) syscall = syscall_get_nr(current, regs); } - audit_syscall_entry(syscall, regs->orig_x0, regs->regs[1], - regs->regs[2], regs->regs[3]); + syscall_enter_audit(regs, syscall); return regs->syscallno; } -- 2.34.1
Differ from generic entry, due to historical reasons, ARM64 need to save/restore during syscall entry/exit because ARM64 use a scratch register (ip(r12) on AArch32, x7 on AArch64) to denote syscall entry/exit. In preparation for moving arm64 over to the generic entry code, add arch_ptrace_report_syscall_entry/exit() as the default ptrace_report_syscall_entry/exit() implementation. This allows arm64 to implement the architecture specific version. Suggested-by: Mark Rutland <mark.rutland@arm.com> Suggested-by: Kevin Brodsky <kevin.brodsky@arm.com> Suggested-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Jinjie Ruan <ruanjinjie@huawei.com> --- kernel/entry/syscall-common.c | 43 +++++++++++++++++++++++++++++++++-- 1 file changed, 41 insertions(+), 2 deletions(-) diff --git a/kernel/entry/syscall-common.c b/kernel/entry/syscall-common.c index 66e6ba7fa80c..27310e611567 100644 --- a/kernel/entry/syscall-common.c +++ b/kernel/entry/syscall-common.c @@ -17,6 +17,25 @@ static inline void syscall_enter_audit(struct pt_regs *regs, long syscall) } } +/** + * arch_ptrace_report_syscall_entry - Architecture specific + * ptrace_report_syscall_entry(). + * + * Invoked from syscall_trace_enter() to wrap ptrace_report_syscall_entry(). + * Defaults to ptrace_report_syscall_entry. + * + * The main purpose is to support arch-specific ptrace_report_syscall_entry() + * implementation. + */ +static __always_inline int arch_ptrace_report_syscall_entry(struct pt_regs *regs); + +#ifndef arch_ptrace_report_syscall_entry +static __always_inline int arch_ptrace_report_syscall_entry(struct pt_regs *regs) +{ + return ptrace_report_syscall_entry(regs); +} +#endif + long syscall_trace_enter(struct pt_regs *regs, long syscall, unsigned long work) { @@ -34,7 +53,7 @@ long syscall_trace_enter(struct pt_regs *regs, long syscall, /* Handle ptrace */ if (work & (SYSCALL_WORK_SYSCALL_TRACE | SYSCALL_WORK_SYSCALL_EMU)) { - ret = ptrace_report_syscall_entry(regs); + ret = arch_ptrace_report_syscall_entry(regs); if (ret || (work & SYSCALL_WORK_SYSCALL_EMU)) return -1L; } @@ -84,6 +103,26 @@ static inline bool report_single_step(unsigned long work) return work & SYSCALL_WORK_SYSCALL_EXIT_TRAP; } +/** + * arch_ptrace_report_syscall_exit - Architecture specific + * ptrace_report_syscall_exit. + * + * Invoked from syscall_exit_work() to wrap ptrace_report_syscall_exit(). + * + * The main purpose is to support arch-specific ptrace_report_syscall_exit + * implementation. + */ +static __always_inline void arch_ptrace_report_syscall_exit(struct pt_regs *regs, + int step); + +#ifndef arch_ptrace_report_syscall_exit +static __always_inline void arch_ptrace_report_syscall_exit(struct pt_regs *regs, + int step) +{ + ptrace_report_syscall_exit(regs, step); +} +#endif + void syscall_exit_work(struct pt_regs *regs, unsigned long work) { bool step; @@ -108,5 +147,5 @@ void syscall_exit_work(struct pt_regs *regs, unsigned long work) step = report_single_step(work); if (step || work & SYSCALL_WORK_SYSCALL_TRACE) - ptrace_report_syscall_exit(regs, step); + arch_ptrace_report_syscall_exit(regs, step); } -- 2.34.1
Add has_syscall_work() helper to facilitate reuse of this function in other places. No functional changes. Signed-off-by: Jinjie Ruan <ruanjinjie@huawei.com> --- include/linux/entry-common.h | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/include/linux/entry-common.h b/include/linux/entry-common.h index cd6dacb2d8bf..e0f94e937e84 100644 --- a/include/linux/entry-common.h +++ b/include/linux/entry-common.h @@ -44,6 +44,11 @@ SYSCALL_WORK_SYSCALL_EXIT_TRAP | \ ARCH_SYSCALL_WORK_EXIT) +static inline bool has_syscall_work(unsigned long work) +{ + return unlikely(work & SYSCALL_WORK_ENTER); +} + /** * syscall_enter_from_user_mode_prepare - Establish state and enable interrupts * @regs: Pointer to currents pt_regs @@ -91,7 +96,7 @@ static __always_inline long syscall_enter_from_user_mode_work(struct pt_regs *re { unsigned long work = READ_ONCE(current_thread_info()->syscall_work); - if (work & SYSCALL_WORK_ENTER) + if (has_syscall_work(work)) syscall = syscall_trace_enter(regs, syscall, work); return syscall; -- 2.34.1
Currently, x86, Riscv, Loongarch use the generic entry which makes maintainers' work easier and codes more elegant. arm64 has already switched to the generic IRQ entry, so completely convert arm64 to use the generic entry infrastructure from kernel/entry/*. The changes are below: - Remove TIF_SYSCALL_* flag, _TIF_WORK_MASK, _TIF_SYSCALL_WORK. - Implement arch_ptrace_report_syscall_entry/exit() with report_syscall_enter/exit() to do arm64-specific save/restore during syscall entry/exit. - Remove arm64 syscall_trace_enter(), syscall_exit_to_user_mode_prepare(), and related sub-functions including syscall_trace_exit() and syscall_enter_audit(), by calling generic entry's functions with similar functionality. Suggested-by: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Jinjie Ruan <ruanjinjie@huawei.com> --- arch/arm64/Kconfig | 2 +- arch/arm64/include/asm/entry-common.h | 69 +++++++++++++ arch/arm64/include/asm/syscall.h | 7 +- arch/arm64/include/asm/thread_info.h | 22 +---- arch/arm64/kernel/debug-monitors.c | 7 ++ arch/arm64/kernel/ptrace.c | 134 -------------------------- arch/arm64/kernel/signal.c | 2 +- arch/arm64/kernel/syscall.c | 6 +- 8 files changed, 85 insertions(+), 164 deletions(-) diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index 6bb60a0620ec..0d4954049032 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -149,9 +149,9 @@ config ARM64 select GENERIC_CPU_DEVICES select GENERIC_CPU_VULNERABILITIES select GENERIC_EARLY_IOREMAP + select GENERIC_ENTRY select GENERIC_IDLE_POLL_SETUP select GENERIC_IOREMAP - select GENERIC_IRQ_ENTRY select GENERIC_IRQ_IPI select GENERIC_IRQ_KEXEC_CLEAR_VM_FORWARD select GENERIC_IRQ_PROBE diff --git a/arch/arm64/include/asm/entry-common.h b/arch/arm64/include/asm/entry-common.h index cab8cd78f693..ae3ed608c9fa 100644 --- a/arch/arm64/include/asm/entry-common.h +++ b/arch/arm64/include/asm/entry-common.h @@ -11,6 +11,11 @@ #include <asm/mte.h> #include <asm/stacktrace.h> +enum ptrace_syscall_dir { + PTRACE_SYSCALL_ENTER = 0, + PTRACE_SYSCALL_EXIT, +}; + #define ARCH_EXIT_TO_USER_MODE_WORK (_TIF_MTE_ASYNC_FAULT | _TIF_FOREIGN_FPSTATE) static __always_inline void arch_exit_to_user_mode_work(struct pt_regs *regs, @@ -54,4 +59,68 @@ static inline bool arch_irqentry_exit_need_resched(void) #define arch_irqentry_exit_need_resched arch_irqentry_exit_need_resched +static inline int arch_ptrace_report_syscall_entry(struct pt_regs *regs) +{ + unsigned long saved_reg; + int regno, ret; + + /* + * We have some ABI weirdness here in the way that we handle syscall + * exit stops because we indicate whether or not the stop has been + * signalled from syscall entry or syscall exit by clobbering a general + * purpose register (ip/r12 for AArch32, x7 for AArch64) in the tracee + * and restoring its old value after the stop. This means that: + * + * - Any writes by the tracer to this register during the stop are + * ignored/discarded. + * + * - The actual value of the register is not available during the stop, + * so the tracer cannot save it and restore it later. + * + * - Syscall stops behave differently to seccomp and pseudo-step traps + * (the latter do not nobble any registers). + */ + regno = (is_compat_task() ? 12 : 7); + saved_reg = regs->regs[regno]; + regs->regs[regno] = PTRACE_SYSCALL_ENTER; + + ret = ptrace_report_syscall_entry(regs); + if (ret) + forget_syscall(regs); + + regs->regs[regno] = saved_reg; + + return ret; +} + +#define arch_ptrace_report_syscall_entry arch_ptrace_report_syscall_entry + +static inline void arch_ptrace_report_syscall_exit(struct pt_regs *regs, + int step) +{ + unsigned long saved_reg; + int regno; + + /* See comment for arch_ptrace_report_syscall_entry() */ + regno = (is_compat_task() ? 12 : 7); + saved_reg = regs->regs[regno]; + regs->regs[regno] = PTRACE_SYSCALL_EXIT; + + if (!step) { + ptrace_report_syscall_exit(regs, 0); + regs->regs[regno] = saved_reg; + } else { + regs->regs[regno] = saved_reg; + + /* + * Signal a pseudo-step exception since we are stepping but + * tracer modifications to the registers may have rewound the + * state machine. + */ + ptrace_report_syscall_exit(regs, 1); + } +} + +#define arch_ptrace_report_syscall_exit arch_ptrace_report_syscall_exit + #endif /* _ASM_ARM64_ENTRY_COMMON_H */ diff --git a/arch/arm64/include/asm/syscall.h b/arch/arm64/include/asm/syscall.h index 6225981fbbdb..235cd0eaab47 100644 --- a/arch/arm64/include/asm/syscall.h +++ b/arch/arm64/include/asm/syscall.h @@ -114,12 +114,9 @@ static inline int syscall_get_arch(struct task_struct *task) return AUDIT_ARCH_AARCH64; } -static inline bool has_syscall_work(unsigned long flags) +static inline bool arch_syscall_is_vdso_sigreturn(struct pt_regs *regs) { - return unlikely(flags & _TIF_SYSCALL_WORK); + return false; } -int syscall_trace_enter(struct pt_regs *regs, long syscall, unsigned long flags); -void syscall_exit_to_user_mode_prepare(struct pt_regs *regs); - #endif /* __ASM_SYSCALL_H */ diff --git a/arch/arm64/include/asm/thread_info.h b/arch/arm64/include/asm/thread_info.h index f241b8601ebd..0c083be23018 100644 --- a/arch/arm64/include/asm/thread_info.h +++ b/arch/arm64/include/asm/thread_info.h @@ -43,6 +43,7 @@ struct thread_info { void *scs_sp; #endif u32 cpu; + unsigned long syscall_work; /* SYSCALL_WORK_ flags */ }; #define thread_saved_pc(tsk) \ @@ -65,11 +66,6 @@ void arch_setup_new_exec(void); #define TIF_UPROBE 5 /* uprobe breakpoint or singlestep */ #define TIF_MTE_ASYNC_FAULT 6 /* MTE Asynchronous Tag Check Fault */ #define TIF_NOTIFY_SIGNAL 7 /* signal notifications exist */ -#define TIF_SYSCALL_TRACE 8 /* syscall trace active */ -#define TIF_SYSCALL_AUDIT 9 /* syscall auditing */ -#define TIF_SYSCALL_TRACEPOINT 10 /* syscall tracepoint for ftrace */ -#define TIF_SECCOMP 11 /* syscall secure computing */ -#define TIF_SYSCALL_EMU 12 /* syscall emulation active */ #define TIF_PATCH_PENDING 13 /* pending live patching update */ #define TIF_MEMDIE 18 /* is terminating due to OOM killer */ #define TIF_FREEZE 19 @@ -92,30 +88,14 @@ void arch_setup_new_exec(void); #define _TIF_NEED_RESCHED_LAZY (1 << TIF_NEED_RESCHED_LAZY) #define _TIF_NOTIFY_RESUME (1 << TIF_NOTIFY_RESUME) #define _TIF_FOREIGN_FPSTATE (1 << TIF_FOREIGN_FPSTATE) -#define _TIF_SYSCALL_TRACE (1 << TIF_SYSCALL_TRACE) -#define _TIF_SYSCALL_AUDIT (1 << TIF_SYSCALL_AUDIT) -#define _TIF_SYSCALL_TRACEPOINT (1 << TIF_SYSCALL_TRACEPOINT) -#define _TIF_SECCOMP (1 << TIF_SECCOMP) -#define _TIF_SYSCALL_EMU (1 << TIF_SYSCALL_EMU) #define _TIF_PATCH_PENDING (1 << TIF_PATCH_PENDING) #define _TIF_UPROBE (1 << TIF_UPROBE) -#define _TIF_SINGLESTEP (1 << TIF_SINGLESTEP) #define _TIF_32BIT (1 << TIF_32BIT) #define _TIF_SVE (1 << TIF_SVE) #define _TIF_MTE_ASYNC_FAULT (1 << TIF_MTE_ASYNC_FAULT) #define _TIF_NOTIFY_SIGNAL (1 << TIF_NOTIFY_SIGNAL) #define _TIF_TSC_SIGSEGV (1 << TIF_TSC_SIGSEGV) -#define _TIF_WORK_MASK (_TIF_NEED_RESCHED | _TIF_NEED_RESCHED_LAZY | \ - _TIF_NOTIFY_RESUME | _TIF_FOREIGN_FPSTATE | \ - _TIF_UPROBE | _TIF_MTE_ASYNC_FAULT | \ - _TIF_NOTIFY_SIGNAL | _TIF_SIGPENDING | \ - _TIF_PATCH_PENDING) - -#define _TIF_SYSCALL_WORK (_TIF_SYSCALL_TRACE | _TIF_SYSCALL_AUDIT | \ - _TIF_SYSCALL_TRACEPOINT | _TIF_SECCOMP | \ - _TIF_SYSCALL_EMU) - #ifdef CONFIG_SHADOW_CALL_STACK #define INIT_SCS \ .scs_base = init_shadow_call_stack, \ diff --git a/arch/arm64/kernel/debug-monitors.c b/arch/arm64/kernel/debug-monitors.c index 85fc162a6f9b..5c026b9f4a6f 100644 --- a/arch/arm64/kernel/debug-monitors.c +++ b/arch/arm64/kernel/debug-monitors.c @@ -385,11 +385,18 @@ void user_enable_single_step(struct task_struct *task) if (!test_and_set_ti_thread_flag(ti, TIF_SINGLESTEP)) set_regs_spsr_ss(task_pt_regs(task)); + + /* + * Ensure that a trap is triggered once stepping out of a system + * call prior to executing any user instruction. + */ + set_task_syscall_work(task, SYSCALL_EXIT_TRAP); } NOKPROBE_SYMBOL(user_enable_single_step); void user_disable_single_step(struct task_struct *task) { clear_ti_thread_flag(task_thread_info(task), TIF_SINGLESTEP); + clear_task_syscall_work(task, SYSCALL_EXIT_TRAP); } NOKPROBE_SYMBOL(user_disable_single_step); diff --git a/arch/arm64/kernel/ptrace.c b/arch/arm64/kernel/ptrace.c index 9455ccf1ecc1..9e3b39e207d1 100644 --- a/arch/arm64/kernel/ptrace.c +++ b/arch/arm64/kernel/ptrace.c @@ -42,9 +42,6 @@ #include <asm/traps.h> #include <asm/system_misc.h> -#define CREATE_TRACE_POINTS -#include <trace/events/syscalls.h> - struct pt_regs_offset { const char *name; int offset; @@ -2312,137 +2309,6 @@ long arch_ptrace(struct task_struct *child, long request, return ptrace_request(child, request, addr, data); } -enum ptrace_syscall_dir { - PTRACE_SYSCALL_ENTER = 0, - PTRACE_SYSCALL_EXIT, -}; - -static int report_syscall_enter(struct pt_regs *regs) -{ - unsigned long saved_reg; - int regno, ret; - - /* - * We have some ABI weirdness here in the way that we handle syscall - * exit stops because we indicate whether or not the stop has been - * signalled from syscall entry or syscall exit by clobbering a general - * purpose register (ip/r12 for AArch32, x7 for AArch64) in the tracee - * and restoring its old value after the stop. This means that: - * - * - Any writes by the tracer to this register during the stop are - * ignored/discarded. - * - * - The actual value of the register is not available during the stop, - * so the tracer cannot save it and restore it later. - * - * - Syscall stops behave differently to seccomp and pseudo-step traps - * (the latter do not nobble any registers). - */ - regno = (is_compat_task() ? 12 : 7); - saved_reg = regs->regs[regno]; - regs->regs[regno] = PTRACE_SYSCALL_ENTER; - - ret = ptrace_report_syscall_entry(regs); - if (ret) - forget_syscall(regs); - - regs->regs[regno] = saved_reg; - - return ret; -} - -static void report_syscall_exit(struct pt_regs *regs) -{ - int regno; - unsigned long saved_reg; - - /* See comment for report_syscall_enter() above */ - regno = (is_compat_task() ? 12 : 7); - saved_reg = regs->regs[regno]; - regs->regs[regno] = PTRACE_SYSCALL_EXIT; - - if (!test_thread_flag(TIF_SINGLESTEP)) { - ptrace_report_syscall_exit(regs, 0); - regs->regs[regno] = saved_reg; - } else { - regs->regs[regno] = saved_reg; - - /* - * Signal a pseudo-step exception since we are stepping but - * tracer modifications to the registers may have rewound the - * state machine. - */ - ptrace_report_syscall_exit(regs, 1); - } -} - -static inline void syscall_enter_audit(struct pt_regs *regs, long syscall) -{ - if (unlikely(audit_context())) { - unsigned long args[6]; - - syscall_get_arguments(current, regs, args); - audit_syscall_entry(syscall, args[0], args[1], args[2], args[3]); - } - -} - -int syscall_trace_enter(struct pt_regs *regs, long syscall, unsigned long flags) -{ - int ret; - - if (flags & (_TIF_SYSCALL_EMU | _TIF_SYSCALL_TRACE)) { - ret = report_syscall_enter(regs); - if (ret || (flags & _TIF_SYSCALL_EMU)) - return NO_SYSCALL; - } - - /* Do the secure computing after ptrace; failures should be fast. */ - if (flags & _TIF_SECCOMP) { - ret = __secure_computing(NULL); - if (ret == -1L) - return NO_SYSCALL; - } - - /* Either of the above might have changed the syscall number */ - syscall = syscall_get_nr(current, regs); - - if (test_thread_flag(TIF_SYSCALL_TRACEPOINT)) { - trace_sys_enter(regs, syscall); - - /* - * Probes or BPF hooks in the tracepoint may have changed the - * system call number as well. - */ - syscall = syscall_get_nr(current, regs); - } - - syscall_enter_audit(regs, syscall); - - return regs->syscallno; -} - -static void syscall_trace_exit(struct pt_regs *regs, unsigned long flags) -{ - audit_syscall_exit(regs); - - if (flags & _TIF_SYSCALL_TRACEPOINT) - trace_sys_exit(regs, syscall_get_return_value(current, regs)); - - if (flags & (_TIF_SYSCALL_TRACE | _TIF_SINGLESTEP)) - report_syscall_exit(regs); -} - -void syscall_exit_to_user_mode_prepare(struct pt_regs *regs) -{ - unsigned long flags = read_thread_flags(); - - rseq_syscall(regs); - - if (has_syscall_work(flags) || flags & _TIF_SINGLESTEP) - syscall_trace_exit(regs, flags); -} - /* * SPSR_ELx bits which are always architecturally RES0 per ARM DDI 0487D.a. * We permit userspace to set SSBS (AArch64 bit 12, AArch32 bit 23) which is diff --git a/arch/arm64/kernel/signal.c b/arch/arm64/kernel/signal.c index 1110eeb21f57..d3ec1892b3c7 100644 --- a/arch/arm64/kernel/signal.c +++ b/arch/arm64/kernel/signal.c @@ -8,8 +8,8 @@ #include <linux/cache.h> #include <linux/compat.h> +#include <linux/entry-common.h> #include <linux/errno.h> -#include <linux/irq-entry-common.h> #include <linux/kernel.h> #include <linux/signal.h> #include <linux/freezer.h> diff --git a/arch/arm64/kernel/syscall.c b/arch/arm64/kernel/syscall.c index a50db885fc34..5aa585111c4b 100644 --- a/arch/arm64/kernel/syscall.c +++ b/arch/arm64/kernel/syscall.c @@ -2,6 +2,7 @@ #include <linux/compiler.h> #include <linux/context_tracking.h> +#include <linux/entry-common.h> #include <linux/errno.h> #include <linux/nospec.h> #include <linux/ptrace.h> @@ -68,6 +69,7 @@ static void invoke_syscall(struct pt_regs *regs, unsigned int scno, static void el0_svc_common(struct pt_regs *regs, int scno, int sc_nr, const syscall_fn_t syscall_table[]) { + unsigned long work = READ_ONCE(current_thread_info()->syscall_work); unsigned long flags = read_thread_flags(); regs->orig_x0 = regs->regs[0]; @@ -101,7 +103,7 @@ static void el0_svc_common(struct pt_regs *regs, int scno, int sc_nr, return; } - if (has_syscall_work(flags)) { + if (has_syscall_work(work)) { /* * The de-facto standard way to skip a system call using ptrace * is to set the system call to -1 (NO_SYSCALL) and set x0 to a @@ -119,7 +121,7 @@ static void el0_svc_common(struct pt_regs *regs, int scno, int sc_nr, */ if (scno == NO_SYSCALL) syscall_set_return_value(current, regs, -ENOSYS, 0); - scno = syscall_trace_enter(regs, regs->syscallno, flags); + scno = syscall_trace_enter(regs, regs->syscallno, work); if (scno == NO_SYSCALL) { syscall_exit_to_user_mode_prepare(regs); return; -- 2.34.1
participants (1)
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Jinjie Ruan