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Date: Tue, 20 Sep 2022 11:37:11 +0800 From: Tiezhu Yang <yangtiezhu@...ngson.cn> To: Huacai Chen <chenhuacai@...nel.org>, Masami Hiramatsu <mhiramat@...nel.org> Cc: loongarch@...ts.linux.dev, linux-kernel@...r.kernel.org Subject: [PATCH 1/4] LoongArch: Add kprobe support Kprobes allows you to trap at almost any kernel address and execute a callback function, this commit adds kprobe support for LoongArch. Signed-off-by: Tiezhu Yang <yangtiezhu@...ngson.cn> --- arch/loongarch/Kconfig | 1 + arch/loongarch/include/asm/inst.h | 31 ++++ arch/loongarch/include/asm/kprobes.h | 44 +++++ arch/loongarch/include/asm/ptrace.h | 1 + arch/loongarch/kernel/Makefile | 2 + arch/loongarch/kernel/inst.c | 107 ++++++++++++ arch/loongarch/kernel/kprobes.c | 309 +++++++++++++++++++++++++++++++++++ 7 files changed, 495 insertions(+) create mode 100644 arch/loongarch/include/asm/kprobes.h create mode 100644 arch/loongarch/kernel/kprobes.c diff --git a/arch/loongarch/Kconfig b/arch/loongarch/Kconfig index 5b5fc94..6b01073 100644 --- a/arch/loongarch/Kconfig +++ b/arch/loongarch/Kconfig @@ -94,6 +94,7 @@ config LOONGARCH select HAVE_IOREMAP_PROT select HAVE_IRQ_EXIT_ON_IRQ_STACK select HAVE_IRQ_TIME_ACCOUNTING + select HAVE_KPROBES select HAVE_MOD_ARCH_SPECIFIC select HAVE_NMI select HAVE_PCI diff --git a/arch/loongarch/include/asm/inst.h b/arch/loongarch/include/asm/inst.h index fce1843..fc8879b 100644 --- a/arch/loongarch/include/asm/inst.h +++ b/arch/loongarch/include/asm/inst.h @@ -7,6 +7,7 @@ #include <linux/types.h> #include <asm/asm.h> +#include <asm/ptrace.h> #define INSN_BREAK 0x002a0000 @@ -20,6 +21,10 @@ #define ADDR_IMM(addr, INSN) ((addr & ADDR_IMMMASK_##INSN) >> ADDR_IMMSHIFT_##INSN) +enum reg0i15_op { + break_op = 0x54, +}; + enum reg0i26_op { b_op = 0x14, bl_op = 0x15, @@ -28,6 +33,8 @@ enum reg0i26_op { enum reg1i20_op { lu12iw_op = 0x0a, lu32id_op = 0x0b, + pcaddi_op = 0x0c, + pcalau12i_op = 0x0d, pcaddu12i_op = 0x0e, pcaddu18i_op = 0x0f, }; @@ -35,6 +42,8 @@ enum reg1i20_op { enum reg1i21_op { beqz_op = 0x10, bnez_op = 0x11, + bceqz_op = 0x48000000, + bcnez_op = 0x48000100, }; enum reg2_op { @@ -164,6 +173,11 @@ enum reg3sa2_op { alsld_op = 0x16, }; +struct reg0i15_format { + unsigned int immediate : 15; + unsigned int opcode : 17; +}; + struct reg0i26_format { unsigned int immediate_h : 10; unsigned int immediate_l : 16; @@ -249,6 +263,7 @@ struct reg3sa2_format { union loongarch_instruction { unsigned int word; + struct reg0i15_format reg0i15_format; struct reg0i26_format reg0i26_format; struct reg1i20_format reg1i20_format; struct reg1i21_format reg1i21_format; @@ -313,6 +328,12 @@ static inline bool is_branch_ins(union loongarch_instruction *ip) ip->reg1i21_format.opcode <= bgeu_op; } +static inline bool is_pc_ins(union loongarch_instruction *ip) +{ + return ip->reg1i20_format.opcode >= pcaddi_op && + ip->reg1i20_format.opcode <= pcaddu18i_op; +} + static inline bool is_ra_save_ins(union loongarch_instruction *ip) { /* st.d $ra, $sp, offset */ @@ -334,6 +355,16 @@ static inline bool is_stack_alloc_ins(union loongarch_instruction *ip) u32 larch_insn_gen_lu32id(enum loongarch_gpr rd, int imm); u32 larch_insn_gen_lu52id(enum loongarch_gpr rd, enum loongarch_gpr rj, int imm); u32 larch_insn_gen_jirl(enum loongarch_gpr rd, enum loongarch_gpr rj, unsigned long pc, unsigned long dest); +void simu_branch(struct pt_regs *regs, union loongarch_instruction insn); +void simu_pc(struct pt_regs *regs, union loongarch_instruction insn); + +static inline unsigned long sign_extended(unsigned long val, unsigned int idx) +{ + if (val & (1UL << idx)) + return ~((1UL << (idx + 1)) - 1) | val; + else + return ((1UL << (idx + 1)) - 1) & val; +} static inline bool signed_imm_check(long val, unsigned int bit) { diff --git a/arch/loongarch/include/asm/kprobes.h b/arch/loongarch/include/asm/kprobes.h new file mode 100644 index 0000000..afcf254 --- /dev/null +++ b/arch/loongarch/include/asm/kprobes.h @@ -0,0 +1,44 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +#ifndef __ASM_LOONGARCH_KPROBES_H +#define __ASM_LOONGARCH_KPROBES_H + +#include <asm-generic/kprobes.h> + +#ifdef CONFIG_KPROBES + +#include <asm/inst.h> + +#define __ARCH_WANT_KPROBES_INSN_SLOT +#define MAX_INSN_SIZE 2 + +#define flush_insn_slot(p) do { } while (0) +#define kretprobe_blacklist_size 0 + +typedef union loongarch_instruction kprobe_opcode_t; + +/* Architecture specific copy of original instruction */ +struct arch_specific_insn { + /* copy of the original instruction */ + kprobe_opcode_t *insn; +}; + +struct prev_kprobe { + struct kprobe *kp; + unsigned long status; + unsigned long saved_irq; + unsigned long saved_era; +}; + +/* per-cpu kprobe control block */ +struct kprobe_ctlblk { + unsigned long kprobe_status; + unsigned long kprobe_saved_irq; + unsigned long kprobe_saved_era; + struct prev_kprobe prev_kprobe; +}; + +void arch_remove_kprobe(struct kprobe *p); +bool kprobe_fault_handler(struct pt_regs *regs, int trapnr); + +#endif /* CONFIG_KPROBES */ +#endif /* __ASM_LOONGARCH_KPROBES_H */ diff --git a/arch/loongarch/include/asm/ptrace.h b/arch/loongarch/include/asm/ptrace.h index 17838c6..eb9538a 100644 --- a/arch/loongarch/include/asm/ptrace.h +++ b/arch/loongarch/include/asm/ptrace.h @@ -6,6 +6,7 @@ #define _ASM_PTRACE_H #include <asm/page.h> +#include <asm/irqflags.h> #include <asm/thread_info.h> #include <uapi/asm/ptrace.h> diff --git a/arch/loongarch/kernel/Makefile b/arch/loongarch/kernel/Makefile index 5358144..ff98d8a 100644 --- a/arch/loongarch/kernel/Makefile +++ b/arch/loongarch/kernel/Makefile @@ -33,4 +33,6 @@ obj-$(CONFIG_UNWINDER_PROLOGUE) += unwind_prologue.o obj-$(CONFIG_PERF_EVENTS) += perf_event.o perf_regs.o +obj-$(CONFIG_KPROBES) += kprobes.o + CPPFLAGS_vmlinux.lds := $(KBUILD_CFLAGS) diff --git a/arch/loongarch/kernel/inst.c b/arch/loongarch/kernel/inst.c index b1df0ec..143acb6 100644 --- a/arch/loongarch/kernel/inst.c +++ b/arch/loongarch/kernel/inst.c @@ -38,3 +38,110 @@ u32 larch_insn_gen_jirl(enum loongarch_gpr rd, enum loongarch_gpr rj, unsigned l return insn.word; } + +void simu_branch(struct pt_regs *regs, union loongarch_instruction insn) +{ + unsigned int imm, imm_l, imm_h, rd, rj; + unsigned long pc = regs->csr_era; + + imm_l = insn.reg0i26_format.immediate_l; + imm_h = insn.reg0i26_format.immediate_h; + switch (insn.reg0i26_format.opcode) { + case b_op: + regs->csr_era = pc + sign_extended((imm_h << 16 | imm_l) << 2, 27); + return; + case bl_op: + regs->csr_era = pc + sign_extended((imm_h << 16 | imm_l) << 2, 27); + regs->regs[1] = pc + LOONGARCH_INSN_SIZE; + return; + } + + imm_l = insn.reg1i21_format.immediate_l; + imm_h = insn.reg1i21_format.immediate_h; + rj = insn.reg1i21_format.rj; + switch (insn.reg1i21_format.opcode) { + case beqz_op: + if (regs->regs[rj] == 0) + regs->csr_era = pc + sign_extended((imm_h << 16 | imm_l) << 2, 22); + else + regs->csr_era = pc + LOONGARCH_INSN_SIZE; + return; + case bnez_op: + if (regs->regs[rj] != 0) + regs->csr_era = pc + sign_extended((imm_h << 16 | imm_l) << 2, 22); + else + regs->csr_era = pc + LOONGARCH_INSN_SIZE; + return; + } + + imm = insn.reg2i16_format.immediate; + rj = insn.reg2i16_format.rj; + rd = insn.reg2i16_format.rd; + switch (insn.reg2i16_format.opcode) { + case beq_op: + if (regs->regs[rj] == regs->regs[rd]) + regs->csr_era = pc + sign_extended(imm << 2, 17); + else + regs->csr_era = pc + LOONGARCH_INSN_SIZE; + break; + case bne_op: + if (regs->regs[rj] != regs->regs[rd]) + regs->csr_era = pc + sign_extended(imm << 2, 17); + else + regs->csr_era = pc + LOONGARCH_INSN_SIZE; + break; + case blt_op: + if ((long)regs->regs[rj] < (long)regs->regs[rd]) + regs->csr_era = pc + sign_extended(imm << 2, 17); + else + regs->csr_era = pc + LOONGARCH_INSN_SIZE; + break; + case bge_op: + if ((long)regs->regs[rj] >= (long)regs->regs[rd]) + regs->csr_era = pc + sign_extended(imm << 2, 17); + else + regs->csr_era = pc + LOONGARCH_INSN_SIZE; + break; + case bltu_op: + if (regs->regs[rj] < regs->regs[rd]) + regs->csr_era = pc + sign_extended(imm << 2, 17); + else + regs->csr_era = pc + LOONGARCH_INSN_SIZE; + break; + case bgeu_op: + if (regs->regs[rj] >= regs->regs[rd]) + regs->csr_era = pc + sign_extended(imm << 2, 17); + else + regs->csr_era = pc + LOONGARCH_INSN_SIZE; + break; + case jirl_op: + regs->csr_era = regs->regs[rj] + sign_extended(imm << 2, 17); + regs->regs[rd] = pc + LOONGARCH_INSN_SIZE; + break; + } +} + +void simu_pc(struct pt_regs *regs, union loongarch_instruction insn) +{ + unsigned long pc = regs->csr_era; + unsigned int rd = insn.reg1i20_format.rd; + unsigned int imm = insn.reg1i20_format.immediate; + + switch (insn.reg1i20_format.opcode) { + case pcaddi_op: + regs->regs[rd] = pc + sign_extended(imm << 2, 21); + break; + case pcaddu12i_op: + regs->regs[rd] = pc + sign_extended(imm << 12, 31); + break; + case pcaddu18i_op: + regs->regs[rd] = pc + sign_extended(imm << 18, 37); + break; + case pcalau12i_op: + regs->regs[rd] = pc + sign_extended(imm << 12, 31); + regs->regs[rd] &= ~((1 << 12) - 1); + break; + } + + regs->csr_era += LOONGARCH_INSN_SIZE; +} diff --git a/arch/loongarch/kernel/kprobes.c b/arch/loongarch/kernel/kprobes.c new file mode 100644 index 0000000..b2c73a5 --- /dev/null +++ b/arch/loongarch/kernel/kprobes.c @@ -0,0 +1,309 @@ +// SPDX-License-Identifier: GPL-2.0-only +#include <linux/kprobes.h> +#include <linux/kdebug.h> +#include <asm/break.h> + +static const union loongarch_instruction breakpoint_insn = { + .reg0i15_format = { + .opcode = break_op, + .immediate = BRK_KPROBE_BP, + } +}; + +static const union loongarch_instruction singlestep_insn = { + .reg0i15_format = { + .opcode = break_op, + .immediate = BRK_KPROBE_SSTEPBP, + } +}; + +DEFINE_PER_CPU(struct kprobe *, current_kprobe); +DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk); + +static bool insns_are_not_supported(union loongarch_instruction insn) +{ + switch (insn.reg2i14_format.opcode) { + case llw_op: + case lld_op: + case scw_op: + case scd_op: + pr_notice("kprobe: ll or sc instructions are not supported\n"); + return true; + } + + switch (insn.reg1i21_format.opcode) { + case bceqz_op: + case bcnez_op: + pr_notice("kprobe: bceqz or bcnez instructions are not supported\n"); + return true; + } + + return false; +} +NOKPROBE_SYMBOL(insns_are_not_supported); + +int arch_prepare_kprobe(struct kprobe *p) +{ + union loongarch_instruction insn; + + insn = p->addr[0]; + if (insns_are_not_supported(insn)) + return -EINVAL; + + p->ainsn.insn = get_insn_slot(); + if (!p->ainsn.insn) + return -ENOMEM; + + p->ainsn.insn[0] = *p->addr; + p->ainsn.insn[1] = singlestep_insn; + + p->opcode = *p->addr; + + return 0; +} +NOKPROBE_SYMBOL(arch_prepare_kprobe); + +/* Install breakpoint in text */ +void arch_arm_kprobe(struct kprobe *p) +{ + *p->addr = breakpoint_insn; +} +NOKPROBE_SYMBOL(arch_arm_kprobe); + +/* Remove breakpoint from text */ +void arch_disarm_kprobe(struct kprobe *p) +{ + *p->addr = p->opcode; +} +NOKPROBE_SYMBOL(arch_disarm_kprobe); + +void arch_remove_kprobe(struct kprobe *p) +{ + if (p->ainsn.insn) { + free_insn_slot(p->ainsn.insn, 0); + p->ainsn.insn = NULL; + } +} +NOKPROBE_SYMBOL(arch_remove_kprobe); + +static void save_previous_kprobe(struct kprobe_ctlblk *kcb) +{ + kcb->prev_kprobe.kp = kprobe_running(); + kcb->prev_kprobe.status = kcb->kprobe_status; + kcb->prev_kprobe.saved_irq = kcb->kprobe_saved_irq; + kcb->prev_kprobe.saved_era = kcb->kprobe_saved_era; +} +NOKPROBE_SYMBOL(save_previous_kprobe); + +static void restore_previous_kprobe(struct kprobe_ctlblk *kcb) +{ + __this_cpu_write(current_kprobe, kcb->prev_kprobe.kp); + kcb->kprobe_status = kcb->prev_kprobe.status; + kcb->kprobe_saved_irq = kcb->prev_kprobe.saved_irq; + kcb->kprobe_saved_era = kcb->prev_kprobe.saved_era; +} +NOKPROBE_SYMBOL(restore_previous_kprobe); + +static void set_current_kprobe(struct kprobe *p, struct pt_regs *regs, + struct kprobe_ctlblk *kcb) +{ + __this_cpu_write(current_kprobe, p); + kcb->kprobe_saved_irq = regs->csr_prmd & CSR_PRMD_PIE; + kcb->kprobe_saved_era = regs->csr_era; +} +NOKPROBE_SYMBOL(set_current_kprobe); + +static bool insns_are_not_simulated(struct kprobe *p, struct pt_regs *regs) +{ + if (is_branch_ins(&p->opcode)) { + simu_branch(regs, p->opcode); + return false; + } else if (is_pc_ins(&p->opcode)) { + simu_pc(regs, p->opcode); + return false; + } else { + return true; + } +} +NOKPROBE_SYMBOL(insns_are_not_simulated); + +static void setup_singlestep(struct kprobe *p, struct pt_regs *regs, + struct kprobe_ctlblk *kcb, int reenter) +{ + if (reenter) { + save_previous_kprobe(kcb); + set_current_kprobe(p, regs, kcb); + kcb->kprobe_status = KPROBE_REENTER; + } else { + kcb->kprobe_status = KPROBE_HIT_SS; + } + + if (p->ainsn.insn->word == breakpoint_insn.word) { + regs->csr_prmd &= ~CSR_PRMD_PIE; + regs->csr_prmd |= kcb->kprobe_saved_irq; + return; + } + + regs->csr_prmd &= ~CSR_PRMD_PIE; + + if (insns_are_not_simulated(p, regs)) { + kcb->kprobe_status = KPROBE_HIT_SS; + regs->csr_era = (unsigned long)&p->ainsn.insn[0]; + } else { + kcb->kprobe_status = KPROBE_HIT_SSDONE; + if (p->post_handler) + p->post_handler(p, regs, 0); + reset_current_kprobe(); + } +} +NOKPROBE_SYMBOL(setup_singlestep); + +static bool reenter_kprobe(struct kprobe *p, struct pt_regs *regs, + struct kprobe_ctlblk *kcb) +{ + switch (kcb->kprobe_status) { + case KPROBE_HIT_SSDONE: + case KPROBE_HIT_ACTIVE: + kprobes_inc_nmissed_count(p); + setup_singlestep(p, regs, kcb, 1); + break; + case KPROBE_HIT_SS: + case KPROBE_REENTER: + pr_warn("Failed to recover from reentered kprobes.\n"); + dump_kprobe(p); + BUG(); + break; + default: + WARN_ON(1); + return false; + } + + return true; +} +NOKPROBE_SYMBOL(reenter_kprobe); + +static bool kprobe_pre_handler(struct pt_regs *regs) +{ + struct kprobe *p, *cur_kprobe; + struct kprobe_ctlblk *kcb; + unsigned long addr = instruction_pointer(regs); + + kcb = get_kprobe_ctlblk(); + cur_kprobe = kprobe_running(); + + p = get_kprobe((kprobe_opcode_t *) addr); + if (p) { + if (cur_kprobe) { + if (reenter_kprobe(p, regs, kcb)) + return true; + } else { + /* Probe hit */ + set_current_kprobe(p, regs, kcb); + kcb->kprobe_status = KPROBE_HIT_ACTIVE; + + /* + * If we have no pre-handler or it returned 0, we + * continue with normal processing. If we have a + * pre-handler and it returned non-zero, it will + * modify the execution path and no need to single + * stepping. Let's just reset current kprobe and exit. + * + * pre_handler can hit a breakpoint and can step thru + * before return. + */ + if (!p->pre_handler || !p->pre_handler(p, regs)) + setup_singlestep(p, regs, kcb, 0); + else + reset_current_kprobe(); + } + return true; + } + + /* + * The breakpoint instruction was removed right + * after we hit it. Another cpu has removed + * either a probepoint or a debugger breakpoint + * at this address. In either case, no further + * handling of this interrupt is appropriate. + * Return back to original instruction, and continue. + */ + return false; +} +NOKPROBE_SYMBOL(kprobe_pre_handler); + +static inline bool kprobe_post_handler(struct pt_regs *regs) +{ + struct kprobe *cur = kprobe_running(); + struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); + + if (!cur) + return false; + + /* Restore back the original saved kprobes variables and continue */ + if (kcb->kprobe_status == KPROBE_REENTER) { + restore_previous_kprobe(kcb); + return true; + } + + /* Call post handler */ + kcb->kprobe_status = KPROBE_HIT_SSDONE; + if (cur->post_handler) + cur->post_handler(cur, regs, 0); + + regs->csr_era = kcb->kprobe_saved_era + LOONGARCH_INSN_SIZE; + regs->csr_prmd |= kcb->kprobe_saved_irq; + + reset_current_kprobe(); + + return true; +} +NOKPROBE_SYMBOL(kprobe_post_handler); + +bool kprobe_fault_handler(struct pt_regs *regs, int trapnr) +{ + struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); + + if (kcb->kprobe_status & KPROBE_HIT_SS) { + regs->csr_era = kcb->kprobe_saved_era + LOONGARCH_INSN_SIZE; + regs->csr_prmd |= kcb->kprobe_saved_irq; + reset_current_kprobe(); + } + + return false; +} +NOKPROBE_SYMBOL(kprobe_fault_handler); + +int kprobe_exceptions_notify(struct notifier_block *self, + unsigned long val, void *data) +{ + struct die_args *args = (struct die_args *)data; + int ret = NOTIFY_DONE; + + switch (val) { + case DIE_BREAK: + if (kprobe_pre_handler(args->regs)) + ret = NOTIFY_STOP; + break; + case DIE_SSTEPBP: + if (kprobe_post_handler(args->regs)) + ret = NOTIFY_STOP; + break; + case DIE_PAGE_FAULT: + preempt_disable(); + if (kprobe_running() + && kprobe_fault_handler(args->regs, args->trapnr)) + ret = NOTIFY_STOP; + preempt_enable(); + break; + default: + break; + } + + return ret; +} +NOKPROBE_SYMBOL(kprobe_exceptions_notify); + +int __init arch_init_kprobes(void) +{ + return 0; +} -- 2.1.0
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