* [PATCH v2 0/5] Add kprobe and kretprobe support for LoongArch
@ 2022-09-28 0:50 Tiezhu Yang
2022-09-28 0:50 ` [PATCH v2 1/5] LoongArch: Simulate branch and PC instructions Tiezhu Yang
` (5 more replies)
0 siblings, 6 replies; 16+ messages in thread
From: Tiezhu Yang @ 2022-09-28 0:50 UTC (permalink / raw)
To: Huacai Chen, Masami Hiramatsu; +Cc: loongarch, linux-kernel
v2:
-- Split simu_branch() and simu_pc() into a single patch
-- Call kprobe_page_fault() in do_page_fault()
-- Add kprobes_trampoline.S for kretprobe
Tiezhu Yang (5):
LoongArch: Simulate branch and PC instructions
LoongArch: Add kprobe support
LoongArch: Add kretprobe support
samples/kprobes: Add LoongArch support
LoongArch: Enable KPROBES in default config
arch/loongarch/Kconfig | 2 +
arch/loongarch/configs/loongson3_defconfig | 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 | 113 ++++++++++
arch/loongarch/kernel/kprobes.c | 336 +++++++++++++++++++++++++++++
arch/loongarch/kernel/kprobes_trampoline.S | 97 +++++++++
arch/loongarch/mm/fault.c | 3 +
samples/kprobes/kprobe_example.c | 8 +
11 files changed, 638 insertions(+)
create mode 100644 arch/loongarch/include/asm/kprobes.h
create mode 100644 arch/loongarch/kernel/kprobes.c
create mode 100644 arch/loongarch/kernel/kprobes_trampoline.S
--
2.1.0
^ permalink raw reply [flat|nested] 16+ messages in thread
* [PATCH v2 1/5] LoongArch: Simulate branch and PC instructions
2022-09-28 0:50 [PATCH v2 0/5] Add kprobe and kretprobe support for LoongArch Tiezhu Yang
@ 2022-09-28 0:50 ` Tiezhu Yang
2022-11-14 4:37 ` Huacai Chen
2022-09-28 0:50 ` [PATCH v2 2/5] LoongArch: Add kprobe support Tiezhu Yang
` (4 subsequent siblings)
5 siblings, 1 reply; 16+ messages in thread
From: Tiezhu Yang @ 2022-09-28 0:50 UTC (permalink / raw)
To: Huacai Chen, Masami Hiramatsu; +Cc: loongarch, linux-kernel
According to LoongArch Reference Manual, simulate branch and
PC instructions, this is preparation for later patch.
Link: https://loongson.github.io/LoongArch-Documentation/LoongArch-Vol1-EN.html#branch-instructions
Link: https://loongson.github.io/LoongArch-Documentation/LoongArch-Vol1-EN.html#_pcaddi_pcaddu121_pcaddu18l_pcalau12i
Co-developed-by: Jinyang He <hejinyang@loongson.cn>
Signed-off-by: Jinyang He <hejinyang@loongson.cn>
Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
---
arch/loongarch/include/asm/inst.h | 19 ++++++
arch/loongarch/include/asm/ptrace.h | 1 +
arch/loongarch/kernel/inst.c | 113 ++++++++++++++++++++++++++++++++++++
3 files changed, 133 insertions(+)
diff --git a/arch/loongarch/include/asm/inst.h b/arch/loongarch/include/asm/inst.h
index fce1843..93d5cd4 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
@@ -28,6 +29,8 @@ enum reg0i26_op {
enum reg1i20_op {
lu12iw_op = 0x0a,
lu32id_op = 0x0b,
+ pcaddi_op = 0x0c,
+ pcalau12i_op = 0x0d,
pcaddu12i_op = 0x0e,
pcaddu18i_op = 0x0f,
};
@@ -313,6 +316,12 @@ 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 +343,16 @@ 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/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/inst.c b/arch/loongarch/kernel/inst.c
index b1df0ec..f5c1eff6 100644
--- a/arch/loongarch/kernel/inst.c
+++ b/arch/loongarch/kernel/inst.c
@@ -38,3 +38,116 @@ 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;
+ default:
+ pr_info("%s: unknown opcode\n", __func__);
+ return;
+ }
+}
+
+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;
+ default:
+ pr_info("%s: unknown opcode\n", __func__);
+ return;
+ }
+
+ regs->csr_era += LOONGARCH_INSN_SIZE;
+}
--
2.1.0
^ permalink raw reply related [flat|nested] 16+ messages in thread
* [PATCH v2 2/5] LoongArch: Add kprobe support
2022-09-28 0:50 [PATCH v2 0/5] Add kprobe and kretprobe support for LoongArch Tiezhu Yang
2022-09-28 0:50 ` [PATCH v2 1/5] LoongArch: Simulate branch and PC instructions Tiezhu Yang
@ 2022-09-28 0:50 ` Tiezhu Yang
2022-11-14 4:41 ` Huacai Chen
2022-09-28 0:50 ` [PATCH v2 3/5] LoongArch: Add kretprobe support Tiezhu Yang
` (3 subsequent siblings)
5 siblings, 1 reply; 16+ messages in thread
From: Tiezhu Yang @ 2022-09-28 0:50 UTC (permalink / raw)
To: Huacai Chen, Masami Hiramatsu; +Cc: loongarch, linux-kernel
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@loongson.cn>
---
arch/loongarch/Kconfig | 1 +
arch/loongarch/include/asm/inst.h | 12 ++
arch/loongarch/include/asm/kprobes.h | 44 +++++
arch/loongarch/kernel/Makefile | 2 +
arch/loongarch/kernel/kprobes.c | 312 +++++++++++++++++++++++++++++++++++
arch/loongarch/mm/fault.c | 3 +
6 files changed, 374 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 be8389f..8debd70 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 93d5cd4..fc8879b 100644
--- a/arch/loongarch/include/asm/inst.h
+++ b/arch/loongarch/include/asm/inst.h
@@ -21,6 +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,
@@ -38,6 +42,8 @@ enum reg1i20_op {
enum reg1i21_op {
beqz_op = 0x10,
bnez_op = 0x11,
+ bceqz_op = 0x48000000,
+ bcnez_op = 0x48000100,
};
enum reg2_op {
@@ -167,6 +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;
@@ -252,6 +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;
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/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/kprobes.c b/arch/loongarch/kernel/kprobes.c
new file mode 100644
index 0000000..c11f6e0
--- /dev/null
+++ b/arch/loongarch/kernel/kprobes.c
@@ -0,0 +1,312 @@
+// 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 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;
+ default:
+ break;
+ }
+
+ return ret;
+}
+NOKPROBE_SYMBOL(kprobe_exceptions_notify);
+
+/*
+ * Provide a blacklist of symbols identifying ranges which cannot be kprobed.
+ * This blacklist is exposed to userspace via debugfs (kprobes/blacklist).
+ */
+int __init arch_populate_kprobe_blacklist(void)
+{
+ return kprobe_add_area_blacklist((unsigned long)__irqentry_text_start,
+ (unsigned long)__irqentry_text_end);
+}
+
+int __init arch_init_kprobes(void)
+{
+ return 0;
+}
diff --git a/arch/loongarch/mm/fault.c b/arch/loongarch/mm/fault.c
index 1ccd536..5882f17 100644
--- a/arch/loongarch/mm/fault.c
+++ b/arch/loongarch/mm/fault.c
@@ -253,6 +253,9 @@ asmlinkage void __kprobes do_page_fault(struct pt_regs *regs,
{
irqentry_state_t state = irqentry_enter(regs);
+ if (kprobe_page_fault(regs, current->thread.trap_nr))
+ return;
+
/* Enable interrupt if enabled in parent context */
if (likely(regs->csr_prmd & CSR_PRMD_PIE))
local_irq_enable();
--
2.1.0
^ permalink raw reply related [flat|nested] 16+ messages in thread
* [PATCH v2 3/5] LoongArch: Add kretprobe support
2022-09-28 0:50 [PATCH v2 0/5] Add kprobe and kretprobe support for LoongArch Tiezhu Yang
2022-09-28 0:50 ` [PATCH v2 1/5] LoongArch: Simulate branch and PC instructions Tiezhu Yang
2022-09-28 0:50 ` [PATCH v2 2/5] LoongArch: Add kprobe support Tiezhu Yang
@ 2022-09-28 0:50 ` Tiezhu Yang
2022-11-14 4:43 ` Huacai Chen
2022-09-28 0:50 ` [PATCH v2 4/5] samples/kprobes: Add LoongArch support Tiezhu Yang
` (2 subsequent siblings)
5 siblings, 1 reply; 16+ messages in thread
From: Tiezhu Yang @ 2022-09-28 0:50 UTC (permalink / raw)
To: Huacai Chen, Masami Hiramatsu; +Cc: loongarch, linux-kernel
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
+
+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
^ permalink raw reply related [flat|nested] 16+ messages in thread
* [PATCH v2 4/5] samples/kprobes: Add LoongArch support
2022-09-28 0:50 [PATCH v2 0/5] Add kprobe and kretprobe support for LoongArch Tiezhu Yang
` (2 preceding siblings ...)
2022-09-28 0:50 ` [PATCH v2 3/5] LoongArch: Add kretprobe support Tiezhu Yang
@ 2022-09-28 0:50 ` Tiezhu Yang
2022-09-28 0:50 ` [PATCH v2 5/5] LoongArch: Enable KPROBES in default config Tiezhu Yang
2022-11-14 4:31 ` [PATCH v2 0/5] Add kprobe and kretprobe support for LoongArch Huacai Chen
5 siblings, 0 replies; 16+ messages in thread
From: Tiezhu Yang @ 2022-09-28 0:50 UTC (permalink / raw)
To: Huacai Chen, Masami Hiramatsu; +Cc: loongarch, linux-kernel
Add LoongArch specific info in handler_pre() and handler_post().
Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
---
samples/kprobes/kprobe_example.c | 8 ++++++++
1 file changed, 8 insertions(+)
diff --git a/samples/kprobes/kprobe_example.c b/samples/kprobes/kprobe_example.c
index fd346f5..ef44c61 100644
--- a/samples/kprobes/kprobe_example.c
+++ b/samples/kprobes/kprobe_example.c
@@ -55,6 +55,10 @@ static int __kprobes handler_pre(struct kprobe *p, struct pt_regs *regs)
pr_info("<%s> p->addr, 0x%p, ip = 0x%lx, flags = 0x%lx\n",
p->symbol_name, p->addr, regs->psw.addr, regs->flags);
#endif
+#ifdef CONFIG_LOONGARCH
+ pr_info("<%s> p->addr = 0x%p, era = 0x%lx, estat = 0x%lx\n",
+ p->symbol_name, p->addr, regs->csr_era, regs->csr_estat);
+#endif
/* A dump_stack() here will give a stack backtrace */
return 0;
@@ -92,6 +96,10 @@ static void __kprobes handler_post(struct kprobe *p, struct pt_regs *regs,
pr_info("<%s> p->addr, 0x%p, flags = 0x%lx\n",
p->symbol_name, p->addr, regs->flags);
#endif
+#ifdef CONFIG_LOONGARCH
+ pr_info("<%s> p->addr = 0x%p, estat = 0x%lx\n",
+ p->symbol_name, p->addr, regs->csr_estat);
+#endif
}
static int __init kprobe_init(void)
--
2.1.0
^ permalink raw reply related [flat|nested] 16+ messages in thread
* [PATCH v2 5/5] LoongArch: Enable KPROBES in default config
2022-09-28 0:50 [PATCH v2 0/5] Add kprobe and kretprobe support for LoongArch Tiezhu Yang
` (3 preceding siblings ...)
2022-09-28 0:50 ` [PATCH v2 4/5] samples/kprobes: Add LoongArch support Tiezhu Yang
@ 2022-09-28 0:50 ` Tiezhu Yang
2022-11-14 4:31 ` [PATCH v2 0/5] Add kprobe and kretprobe support for LoongArch Huacai Chen
5 siblings, 0 replies; 16+ messages in thread
From: Tiezhu Yang @ 2022-09-28 0:50 UTC (permalink / raw)
To: Huacai Chen, Masami Hiramatsu; +Cc: loongarch, linux-kernel
Kprobes for LoongArch is supported now, update loongson3_defconfig
to enable KPROBES.
Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
---
arch/loongarch/configs/loongson3_defconfig | 1 +
1 file changed, 1 insertion(+)
diff --git a/arch/loongarch/configs/loongson3_defconfig b/arch/loongarch/configs/loongson3_defconfig
index c96ce64..8c45043 100644
--- a/arch/loongarch/configs/loongson3_defconfig
+++ b/arch/loongarch/configs/loongson3_defconfig
@@ -60,6 +60,7 @@ CONFIG_ACPI_HOTPLUG_MEMORY=y
CONFIG_EFI_GENERIC_STUB_INITRD_CMDLINE_LOADER=y
CONFIG_EFI_CAPSULE_LOADER=m
CONFIG_EFI_TEST=m
+CONFIG_KPROBES=y
CONFIG_MODULES=y
CONFIG_MODULE_FORCE_LOAD=y
CONFIG_MODULE_UNLOAD=y
--
2.1.0
^ permalink raw reply related [flat|nested] 16+ messages in thread
* Re: [PATCH v2 0/5] Add kprobe and kretprobe support for LoongArch
2022-09-28 0:50 [PATCH v2 0/5] Add kprobe and kretprobe support for LoongArch Tiezhu Yang
` (4 preceding siblings ...)
2022-09-28 0:50 ` [PATCH v2 5/5] LoongArch: Enable KPROBES in default config Tiezhu Yang
@ 2022-11-14 4:31 ` Huacai Chen
2022-11-15 8:44 ` Tiezhu Yang
5 siblings, 1 reply; 16+ messages in thread
From: Huacai Chen @ 2022-11-14 4:31 UTC (permalink / raw)
To: Tiezhu Yang; +Cc: Masami Hiramatsu, loongarch, linux-kernel
Hi, Tiezhu,
Thanks for your patches, however,
1, You should rebase your code, since some functions such as
is_pc_insn is provided in the github's loongarch-next branch;
2, Your code may have some problems about preemption, you can do
something like this commit [1];
3, I don't think Kprobe should be enabled by default, distribution
configs can enable it if needed.
[1] https://github.com/loongson/linux/commit/023d5412ab5c154b87d57d70d465a4243df53717
Huacai
On Wed, Sep 28, 2022 at 8:50 AM Tiezhu Yang <yangtiezhu@loongson.cn> wrote:
>
> v2:
> -- Split simu_branch() and simu_pc() into a single patch
> -- Call kprobe_page_fault() in do_page_fault()
> -- Add kprobes_trampoline.S for kretprobe
>
> Tiezhu Yang (5):
> LoongArch: Simulate branch and PC instructions
> LoongArch: Add kprobe support
> LoongArch: Add kretprobe support
> samples/kprobes: Add LoongArch support
> LoongArch: Enable KPROBES in default config
>
> arch/loongarch/Kconfig | 2 +
> arch/loongarch/configs/loongson3_defconfig | 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 | 113 ++++++++++
> arch/loongarch/kernel/kprobes.c | 336 +++++++++++++++++++++++++++++
> arch/loongarch/kernel/kprobes_trampoline.S | 97 +++++++++
> arch/loongarch/mm/fault.c | 3 +
> samples/kprobes/kprobe_example.c | 8 +
> 11 files changed, 638 insertions(+)
> create mode 100644 arch/loongarch/include/asm/kprobes.h
> create mode 100644 arch/loongarch/kernel/kprobes.c
> create mode 100644 arch/loongarch/kernel/kprobes_trampoline.S
>
> --
> 2.1.0
>
^ permalink raw reply [flat|nested] 16+ messages in thread
* Re: [PATCH v2 1/5] LoongArch: Simulate branch and PC instructions
2022-09-28 0:50 ` [PATCH v2 1/5] LoongArch: Simulate branch and PC instructions Tiezhu Yang
@ 2022-11-14 4:37 ` Huacai Chen
0 siblings, 0 replies; 16+ messages in thread
From: Huacai Chen @ 2022-11-14 4:37 UTC (permalink / raw)
To: Tiezhu Yang; +Cc: Masami Hiramatsu, loongarch, linux-kernel
Hi, Tiezhu,
On Wed, Sep 28, 2022 at 8:50 AM Tiezhu Yang <yangtiezhu@loongson.cn> wrote:
>
> According to LoongArch Reference Manual, simulate branch and
> PC instructions, this is preparation for later patch.
>
> Link: https://loongson.github.io/LoongArch-Documentation/LoongArch-Vol1-EN.html#branch-instructions
> Link: https://loongson.github.io/LoongArch-Documentation/LoongArch-Vol1-EN.html#_pcaddi_pcaddu121_pcaddu18l_pcalau12i
>
> Co-developed-by: Jinyang He <hejinyang@loongson.cn>
> Signed-off-by: Jinyang He <hejinyang@loongson.cn>
> Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
> ---
> arch/loongarch/include/asm/inst.h | 19 ++++++
> arch/loongarch/include/asm/ptrace.h | 1 +
> arch/loongarch/kernel/inst.c | 113 ++++++++++++++++++++++++++++++++++++
> 3 files changed, 133 insertions(+)
>
> diff --git a/arch/loongarch/include/asm/inst.h b/arch/loongarch/include/asm/inst.h
> index fce1843..93d5cd4 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
>
> @@ -28,6 +29,8 @@ enum reg0i26_op {
> enum reg1i20_op {
> lu12iw_op = 0x0a,
> lu32id_op = 0x0b,
> + pcaddi_op = 0x0c,
> + pcalau12i_op = 0x0d,
> pcaddu12i_op = 0x0e,
> pcaddu18i_op = 0x0f,
> };
> @@ -313,6 +316,12 @@ 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 +343,16 @@ 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/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/inst.c b/arch/loongarch/kernel/inst.c
> index b1df0ec..f5c1eff6 100644
> --- a/arch/loongarch/kernel/inst.c
> +++ b/arch/loongarch/kernel/inst.c
> @@ -38,3 +38,116 @@ 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;
> +
In previous versions we checked the alignment of era in simu_branch()
and simu_pc(), now they are unnecessary?
Huacai
> + 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;
> + default:
> + pr_info("%s: unknown opcode\n", __func__);
> + return;
> + }
> +}
> +
> +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;
> + default:
> + pr_info("%s: unknown opcode\n", __func__);
> + return;
> + }
> +
> + regs->csr_era += LOONGARCH_INSN_SIZE;
> +}
> --
> 2.1.0
>
^ permalink raw reply [flat|nested] 16+ messages in thread
* Re: [PATCH v2 2/5] LoongArch: Add kprobe support
2022-09-28 0:50 ` [PATCH v2 2/5] LoongArch: Add kprobe support Tiezhu Yang
@ 2022-11-14 4:41 ` Huacai Chen
0 siblings, 0 replies; 16+ messages in thread
From: Huacai Chen @ 2022-11-14 4:41 UTC (permalink / raw)
To: Tiezhu Yang; +Cc: Masami Hiramatsu, loongarch, linux-kernel
Hi, Tiezhu,
On Wed, Sep 28, 2022 at 8:50 AM Tiezhu Yang <yangtiezhu@loongson.cn> wrote:
>
> 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@loongson.cn>
> ---
> arch/loongarch/Kconfig | 1 +
> arch/loongarch/include/asm/inst.h | 12 ++
> arch/loongarch/include/asm/kprobes.h | 44 +++++
> arch/loongarch/kernel/Makefile | 2 +
> arch/loongarch/kernel/kprobes.c | 312 +++++++++++++++++++++++++++++++++++
> arch/loongarch/mm/fault.c | 3 +
> 6 files changed, 374 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 be8389f..8debd70 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 93d5cd4..fc8879b 100644
> --- a/arch/loongarch/include/asm/inst.h
> +++ b/arch/loongarch/include/asm/inst.h
> @@ -21,6 +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,
> @@ -38,6 +42,8 @@ enum reg1i20_op {
> enum reg1i21_op {
> beqz_op = 0x10,
> bnez_op = 0x11,
> + bceqz_op = 0x48000000,
> + bcnez_op = 0x48000100,
> };
>
> enum reg2_op {
> @@ -167,6 +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;
> @@ -252,6 +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;
> 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)
We don't need an ibar here?
> +#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/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/kprobes.c b/arch/loongarch/kernel/kprobes.c
> new file mode 100644
> index 0000000..c11f6e0
> --- /dev/null
> +++ b/arch/loongarch/kernel/kprobes.c
> @@ -0,0 +1,312 @@
> +// 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 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);
I'm not sure whether kprobe_pre_handler/kprobe_post_handler is
suitable, but nearly all other architectures use
kprobe_handler/post_kprobe_handler.
Huacai
> +
> +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;
> + default:
> + break;
> + }
> +
> + return ret;
> +}
> +NOKPROBE_SYMBOL(kprobe_exceptions_notify);
> +
> +/*
> + * Provide a blacklist of symbols identifying ranges which cannot be kprobed.
> + * This blacklist is exposed to userspace via debugfs (kprobes/blacklist).
> + */
> +int __init arch_populate_kprobe_blacklist(void)
> +{
> + return kprobe_add_area_blacklist((unsigned long)__irqentry_text_start,
> + (unsigned long)__irqentry_text_end);
> +}
> +
> +int __init arch_init_kprobes(void)
> +{
> + return 0;
> +}
> diff --git a/arch/loongarch/mm/fault.c b/arch/loongarch/mm/fault.c
> index 1ccd536..5882f17 100644
> --- a/arch/loongarch/mm/fault.c
> +++ b/arch/loongarch/mm/fault.c
> @@ -253,6 +253,9 @@ asmlinkage void __kprobes do_page_fault(struct pt_regs *regs,
> {
> irqentry_state_t state = irqentry_enter(regs);
>
> + if (kprobe_page_fault(regs, current->thread.trap_nr))
> + return;
> +
> /* Enable interrupt if enabled in parent context */
> if (likely(regs->csr_prmd & CSR_PRMD_PIE))
> local_irq_enable();
> --
> 2.1.0
>
>
^ permalink raw reply [flat|nested] 16+ messages in thread
* Re: [PATCH v2 3/5] LoongArch: Add kretprobe support
2022-09-28 0:50 ` [PATCH v2 3/5] LoongArch: Add kretprobe support Tiezhu Yang
@ 2022-11-14 4:43 ` Huacai Chen
2022-11-14 6:11 ` Jinyang He
0 siblings, 1 reply; 16+ messages in thread
From: Huacai Chen @ 2022-11-14 4:43 UTC (permalink / raw)
To: Tiezhu Yang; +Cc: Masami Hiramatsu, loongarch, linux-kernel
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
>
>
^ permalink raw reply [flat|nested] 16+ messages in thread
* Re: [PATCH v2 3/5] LoongArch: Add kretprobe support
2022-11-14 4:43 ` Huacai Chen
@ 2022-11-14 6:11 ` Jinyang He
2022-11-14 6:50 ` Huacai Chen
0 siblings, 1 reply; 16+ messages in thread
From: Jinyang He @ 2022-11-14 6:11 UTC (permalink / raw)
To: Huacai Chen, Tiezhu Yang; +Cc: Masami Hiramatsu, loongarch, linux-kernel
On 2022/11/14 下午12:43, Huacai Chen wrote:
> 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
Hi, Huacai,
Note that it is not function context. In the original kprobe design, it is
triggered by 'break' and then trap into exception with all pt_regs saved.
The all pt_regs will be visible to the user. So I think in this version
we should also support all regs to user. BTW, due to all exceptions is
trapped by 'break' something in pt_regs is not needed, like estat,
badvaddr and so on.
Thanks,
Jinyang
>> +
>> +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
>>
>>
^ permalink raw reply [flat|nested] 16+ messages in thread
* Re: [PATCH v2 3/5] LoongArch: Add kretprobe support
2022-11-14 6:11 ` Jinyang He
@ 2022-11-14 6:50 ` Huacai Chen
2022-11-14 8:32 ` Jinyang He
0 siblings, 1 reply; 16+ messages in thread
From: Huacai Chen @ 2022-11-14 6:50 UTC (permalink / raw)
To: Jinyang He; +Cc: Tiezhu Yang, Masami Hiramatsu, loongarch, linux-kernel
On Mon, Nov 14, 2022 at 2:11 PM Jinyang He <hejinyang@loongson.cn> wrote:
>
> On 2022/11/14 下午12:43, Huacai Chen wrote:
>
> > 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
>
> Hi, Huacai,
>
>
> Note that it is not function context. In the original kprobe design, it is
> triggered by 'break' and then trap into exception with all pt_regs saved.
> The all pt_regs will be visible to the user. So I think in this version
> we should also support all regs to user. BTW, due to all exceptions is
> trapped by 'break' something in pt_regs is not needed, like estat,
> badvaddr and so on.
OK, but I still have some questions:
1, Why $r0 need save/restore?
2, Why save $r1 but not restore?
3, What is the purpose of CRMD magic?
Huacai
>
>
> Thanks,
>
> Jinyang
>
> >> +
> >> +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
> >>
> >>
>
^ permalink raw reply [flat|nested] 16+ messages in thread
* Re: [PATCH v2 3/5] LoongArch: Add kretprobe support
2022-11-14 6:50 ` Huacai Chen
@ 2022-11-14 8:32 ` Jinyang He
2022-11-14 8:51 ` Huacai Chen
0 siblings, 1 reply; 16+ messages in thread
From: Jinyang He @ 2022-11-14 8:32 UTC (permalink / raw)
To: Huacai Chen; +Cc: Tiezhu Yang, Masami Hiramatsu, loongarch, linux-kernel
On 2022/11/14 下午2:50, Huacai Chen wrote:
> On Mon, Nov 14, 2022 at 2:11 PM Jinyang He <hejinyang@loongson.cn> wrote:
>> On 2022/11/14 下午12:43, Huacai Chen wrote:
>>
>>> 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
>> Hi, Huacai,
>>
>>
>> Note that it is not function context. In the original kprobe design, it is
>> triggered by 'break' and then trap into exception with all pt_regs saved.
>> The all pt_regs will be visible to the user. So I think in this version
>> we should also support all regs to user. BTW, due to all exceptions is
>> trapped by 'break' something in pt_regs is not needed, like estat,
>> badvaddr and so on.
> OK, but I still have some questions:
> 1, Why $r0 need save/restore?
Surely $r0 can be not saved, as now we do not have strange purpose
to make PT_R0 as a flag.
> 2, Why save $r1 but not restore?
My wrong idea is $r1 should be saved at CSR_ERA, to plays it like
exception happened. But its value always equal the address of
__kretprobe_trampoline. The kretprobe is something like fgraph. The real
return address is returned by trampoline_probe_handler. And at present,
the real return address is replaced in pt_regs->csr_era in
__kretprobe_trampoline_handler(). So the $r1 saved in CSR_ERA will
be destroied at __kretprobe_trampoline_handler() actually.
That's why $r1 saved also is not needed.
And both way to get return address from return value or get return address
from pt_regs is same on LoongArch because arch_kretprobe_fixup_return()
does nothing. But I think get return address from pt_regs is more reliable.
> 3, What is the purpose of CRMD magic?
PT_CRMD magic is just exception context. It gives us a chance e.g.
set ie off at func head, and ie on at func return.
Thanks,
Jinyang
>
>>>> +
>>>> +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
>>>>
>>>>
^ permalink raw reply [flat|nested] 16+ messages in thread
* Re: [PATCH v2 3/5] LoongArch: Add kretprobe support
2022-11-14 8:32 ` Jinyang He
@ 2022-11-14 8:51 ` Huacai Chen
2022-11-14 9:26 ` Jinyang He
0 siblings, 1 reply; 16+ messages in thread
From: Huacai Chen @ 2022-11-14 8:51 UTC (permalink / raw)
To: Jinyang He; +Cc: Tiezhu Yang, Masami Hiramatsu, loongarch, linux-kernel
On Mon, Nov 14, 2022 at 4:32 PM Jinyang He <hejinyang@loongson.cn> wrote:
>
> On 2022/11/14 下午2:50, Huacai Chen wrote:
>
> > On Mon, Nov 14, 2022 at 2:11 PM Jinyang He <hejinyang@loongson.cn> wrote:
> >> On 2022/11/14 下午12:43, Huacai Chen wrote:
> >>
> >>> 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
> >> Hi, Huacai,
> >>
> >>
> >> Note that it is not function context. In the original kprobe design, it is
> >> triggered by 'break' and then trap into exception with all pt_regs saved.
> >> The all pt_regs will be visible to the user. So I think in this version
> >> we should also support all regs to user. BTW, due to all exceptions is
> >> trapped by 'break' something in pt_regs is not needed, like estat,
> >> badvaddr and so on.
> > OK, but I still have some questions:
> > 1, Why $r0 need save/restore?
>
> Surely $r0 can be not saved, as now we do not have strange purpose
> to make PT_R0 as a flag.
>
>
> > 2, Why save $r1 but not restore?
> My wrong idea is $r1 should be saved at CSR_ERA, to plays it like
> exception happened. But its value always equal the address of
> __kretprobe_trampoline. The kretprobe is something like fgraph. The real
> return address is returned by trampoline_probe_handler. And at present,
> the real return address is replaced in pt_regs->csr_era in
> __kretprobe_trampoline_handler(). So the $r1 saved in CSR_ERA will
> be destroied at __kretprobe_trampoline_handler() actually.
> That's why $r1 saved also is not needed.
>
> And both way to get return address from return value or get return address
>
> from pt_regs is same on LoongArch because arch_kretprobe_fixup_return()
>
> does nothing. But I think get return address from pt_regs is more reliable.
>
>
> > 3, What is the purpose of CRMD magic?
>
> PT_CRMD magic is just exception context. It gives us a chance e.g.
> set ie off at func head, and ie on at func return.
ARM64 and RISC-V don't have such magics, so maybe they are unneeded?
Huacai
>
>
> Thanks,
>
> Jinyang
>
> >
> >>>> +
> >>>> +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
> >>>>
> >>>>
>
^ permalink raw reply [flat|nested] 16+ messages in thread
* Re: [PATCH v2 3/5] LoongArch: Add kretprobe support
2022-11-14 8:51 ` Huacai Chen
@ 2022-11-14 9:26 ` Jinyang He
0 siblings, 0 replies; 16+ messages in thread
From: Jinyang He @ 2022-11-14 9:26 UTC (permalink / raw)
To: Huacai Chen; +Cc: Tiezhu Yang, Masami Hiramatsu, loongarch, linux-kernel
On 2022/11/14 下午4:51, Huacai Chen wrote:
> On Mon, Nov 14, 2022 at 4:32 PM Jinyang He <hejinyang@loongson.cn> wrote:
>> On 2022/11/14 下午2:50, Huacai Chen wrote:
>>
>>> On Mon, Nov 14, 2022 at 2:11 PM Jinyang He <hejinyang@loongson.cn> wrote:
>>>> On 2022/11/14 下午12:43, Huacai Chen wrote:
>>>>
>>>>> 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
>>>> Hi, Huacai,
>>>>
>>>>
>>>> Note that it is not function context. In the original kprobe design, it is
>>>> triggered by 'break' and then trap into exception with all pt_regs saved.
>>>> The all pt_regs will be visible to the user. So I think in this version
>>>> we should also support all regs to user. BTW, due to all exceptions is
>>>> trapped by 'break' something in pt_regs is not needed, like estat,
>>>> badvaddr and so on.
>>> OK, but I still have some questions:
>>> 1, Why $r0 need save/restore?
>> Surely $r0 can be not saved, as now we do not have strange purpose
>> to make PT_R0 as a flag.
>>
>>
>>> 2, Why save $r1 but not restore?
>> My wrong idea is $r1 should be saved at CSR_ERA, to plays it like
>> exception happened. But its value always equal the address of
>> __kretprobe_trampoline. The kretprobe is something like fgraph. The real
>> return address is returned by trampoline_probe_handler. And at present,
>> the real return address is replaced in pt_regs->csr_era in
>> __kretprobe_trampoline_handler(). So the $r1 saved in CSR_ERA will
>> be destroied at __kretprobe_trampoline_handler() actually.
>> That's why $r1 saved also is not needed.
>>
>> And both way to get return address from return value or get return address
>>
>> from pt_regs is same on LoongArch because arch_kretprobe_fixup_return()
>>
>> does nothing. But I think get return address from pt_regs is more reliable.
>>
>>
>>> 3, What is the purpose of CRMD magic?
>> PT_CRMD magic is just exception context. It gives us a chance e.g.
>> set ie off at func head, and ie on at func return.
> ARM64 and RISC-V don't have such magics, so maybe they are unneeded?
>
ARM64 have noted "Construct a useful saved PSTATE" in kprobes_trampoline.S.
And it seems we provide more interfaces than RISC-V. ?
Thanks,
Jinyang
>>>>>> +
>>>>>> +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
>>>>>>
>>>>>>
^ permalink raw reply [flat|nested] 16+ messages in thread
* Re: [PATCH v2 0/5] Add kprobe and kretprobe support for LoongArch
2022-11-14 4:31 ` [PATCH v2 0/5] Add kprobe and kretprobe support for LoongArch Huacai Chen
@ 2022-11-15 8:44 ` Tiezhu Yang
0 siblings, 0 replies; 16+ messages in thread
From: Tiezhu Yang @ 2022-11-15 8:44 UTC (permalink / raw)
To: Huacai Chen; +Cc: Masami Hiramatsu, loongarch, linux-kernel
On 11/14/2022 12:31 PM, Huacai Chen wrote:
> Hi, Tiezhu,
>
> Thanks for your patches, however,
> 1, You should rebase your code, since some functions such as
> is_pc_insn is provided in the github's loongarch-next branch;
> 2, Your code may have some problems about preemption, you can do
> something like this commit [1];
> 3, I don't think Kprobe should be enabled by default, distribution
> configs can enable it if needed.
>
> [1] https://github.com/loongson/linux/commit/023d5412ab5c154b87d57d70d465a4243df53717
>
OK, thank you, I will rebase and address the review comments,
and then send v3 later.
Thanks,
Tiezhu
^ permalink raw reply [flat|nested] 16+ messages in thread
end of thread, other threads:[~2022-11-15 8:44 UTC | newest]
Thread overview: 16+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2022-09-28 0:50 [PATCH v2 0/5] Add kprobe and kretprobe support for LoongArch Tiezhu Yang
2022-09-28 0:50 ` [PATCH v2 1/5] LoongArch: Simulate branch and PC instructions Tiezhu Yang
2022-11-14 4:37 ` Huacai Chen
2022-09-28 0:50 ` [PATCH v2 2/5] LoongArch: Add kprobe support Tiezhu Yang
2022-11-14 4:41 ` Huacai Chen
2022-09-28 0:50 ` [PATCH v2 3/5] LoongArch: Add kretprobe support Tiezhu Yang
2022-11-14 4:43 ` Huacai Chen
2022-11-14 6:11 ` Jinyang He
2022-11-14 6:50 ` Huacai Chen
2022-11-14 8:32 ` Jinyang He
2022-11-14 8:51 ` Huacai Chen
2022-11-14 9:26 ` Jinyang He
2022-09-28 0:50 ` [PATCH v2 4/5] samples/kprobes: Add LoongArch support Tiezhu Yang
2022-09-28 0:50 ` [PATCH v2 5/5] LoongArch: Enable KPROBES in default config Tiezhu Yang
2022-11-14 4:31 ` [PATCH v2 0/5] Add kprobe and kretprobe support for LoongArch Huacai Chen
2022-11-15 8:44 ` Tiezhu Yang
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