Messages in this thread | | | From | Huacai Chen <> | Date | Mon, 14 Nov 2022 12:43:02 +0800 | Subject | Re: [PATCH v2 3/5] LoongArch: Add kretprobe support |
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Hi, Tiezhu and Jinyang,
On Wed, Sep 28, 2022 at 8:50 AM Tiezhu Yang <yangtiezhu@loongson.cn> wrote: > > Use the generic kretprobe trampoline handler to add kretprobe > support for LoongArch. > > Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn> > --- > arch/loongarch/Kconfig | 1 + > arch/loongarch/kernel/Makefile | 2 +- > arch/loongarch/kernel/kprobes.c | 24 ++++++++ > arch/loongarch/kernel/kprobes_trampoline.S | 97 ++++++++++++++++++++++++++++++ > 4 files changed, 123 insertions(+), 1 deletion(-) > create mode 100644 arch/loongarch/kernel/kprobes_trampoline.S > > diff --git a/arch/loongarch/Kconfig b/arch/loongarch/Kconfig > index 8debd70..877be6a 100644 > --- a/arch/loongarch/Kconfig > +++ b/arch/loongarch/Kconfig > @@ -95,6 +95,7 @@ config LOONGARCH > select HAVE_IRQ_EXIT_ON_IRQ_STACK > select HAVE_IRQ_TIME_ACCOUNTING > select HAVE_KPROBES > + select HAVE_KRETPROBES > select HAVE_MOD_ARCH_SPECIFIC > select HAVE_NMI > select HAVE_PCI > diff --git a/arch/loongarch/kernel/Makefile b/arch/loongarch/kernel/Makefile > index ff98d8a..48f50607 100644 > --- a/arch/loongarch/kernel/Makefile > +++ b/arch/loongarch/kernel/Makefile > @@ -33,6 +33,6 @@ obj-$(CONFIG_UNWINDER_PROLOGUE) += unwind_prologue.o > > obj-$(CONFIG_PERF_EVENTS) += perf_event.o perf_regs.o > > -obj-$(CONFIG_KPROBES) += kprobes.o > +obj-$(CONFIG_KPROBES) += kprobes.o kprobes_trampoline.o > > CPPFLAGS_vmlinux.lds := $(KBUILD_CFLAGS) > diff --git a/arch/loongarch/kernel/kprobes.c b/arch/loongarch/kernel/kprobes.c > index c11f6e0..ca3f1dc 100644 > --- a/arch/loongarch/kernel/kprobes.c > +++ b/arch/loongarch/kernel/kprobes.c > @@ -306,6 +306,30 @@ int __init arch_populate_kprobe_blacklist(void) > (unsigned long)__irqentry_text_end); > } > > +/* 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) > +{ > + return 0; > +} > +NOKPROBE_SYMBOL(arch_trampoline_kprobe); > + > int __init arch_init_kprobes(void) > { > return 0; > diff --git a/arch/loongarch/kernel/kprobes_trampoline.S b/arch/loongarch/kernel/kprobes_trampoline.S > new file mode 100644 > index 0000000..9888ab8 > --- /dev/null > +++ b/arch/loongarch/kernel/kprobes_trampoline.S > @@ -0,0 +1,97 @@ > +/* SPDX-License-Identifier: GPL-2.0+ */ > +#include <linux/linkage.h> > +#include <asm/stackframe.h> > + > + .text > + > + .macro save_all_base_regs > + cfi_st zero, PT_R0 > + cfi_st ra, PT_R1 > + cfi_st tp, PT_R2 > + cfi_st a0, PT_R4 > + cfi_st a1, PT_R5 > + cfi_st a2, PT_R6 > + cfi_st a3, PT_R7 > + cfi_st a4, PT_R8 > + cfi_st a5, PT_R9 > + cfi_st a6, PT_R10 > + cfi_st a7, PT_R11 > + cfi_st t0, PT_R12 > + cfi_st t1, PT_R13 > + cfi_st t2, PT_R14 > + cfi_st t3, PT_R15 > + cfi_st t4, PT_R16 > + cfi_st t5, PT_R17 > + cfi_st t6, PT_R18 > + cfi_st t7, PT_R19 > + cfi_st t8, PT_R20 > + cfi_st u0, PT_R21 > + cfi_st fp, PT_R22 > + cfi_st s0, PT_R23 > + cfi_st s1, PT_R24 > + cfi_st s2, PT_R25 > + cfi_st s3, PT_R26 > + cfi_st s4, PT_R27 > + cfi_st s5, PT_R28 > + cfi_st s6, PT_R29 > + cfi_st s7, PT_R30 > + cfi_st s8, PT_R31 > + addi.d t0, sp, PT_SIZE > + LONG_S t0, sp, PT_R3 > + csrrd t0, LOONGARCH_CSR_CRMD > + andi t0, t0, 0x7 /* extract bit[1:0] PLV, bit[2] IE */ > + LONG_S t0, sp, PT_PRMD > + .endm > + > + .macro restore_all_base_regs > + cfi_ld zero, PT_R0 > + cfi_ld tp, PT_R2 > + cfi_ld a0, PT_R4 > + cfi_ld a1, PT_R5 > + cfi_ld a2, PT_R6 > + cfi_ld a3, PT_R7 > + cfi_ld a4, PT_R8 > + cfi_ld a5, PT_R9 > + cfi_ld a6, PT_R10 > + cfi_ld a7, PT_R11 > + cfi_ld t0, PT_R12 > + cfi_ld t1, PT_R13 > + cfi_ld t2, PT_R14 > + cfi_ld t3, PT_R15 > + cfi_ld t4, PT_R16 > + cfi_ld t5, PT_R17 > + cfi_ld t6, PT_R18 > + cfi_ld t7, PT_R19 > + cfi_ld t8, PT_R20 > + cfi_ld u0, PT_R21 > + cfi_ld fp, PT_R22 > + cfi_ld s0, PT_R23 > + cfi_ld s1, PT_R24 > + cfi_ld s2, PT_R25 > + cfi_ld s3, PT_R26 > + cfi_ld s4, PT_R27 > + cfi_ld s5, PT_R28 > + cfi_ld s6, PT_R29 > + cfi_ld s7, PT_R30 > + cfi_ld s8, PT_R31 > + LONG_L t0, sp, PT_PRMD > + li.d t1, 0x7 /* mask bit[1:0] PLV, bit[2] IE */ > + csrxchg t0, t1, LOONGARCH_CSR_CRMD > + .endm Do you think we need to save and restore all regs here?
Huacai > + > +SYM_CODE_START(__kretprobe_trampoline) > + addi.d sp, sp, -PT_SIZE > + save_all_base_regs > + > + move a0, sp /* pt_regs */ > + > + bl trampoline_probe_handler > + > + /* use the result as the return-address */ > + move ra, a0 > + > + restore_all_base_regs > + addi.d sp, sp, PT_SIZE > + > + jr ra > +SYM_CODE_END(__kretprobe_trampoline) > -- > 2.1.0 > >
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