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Date: Wed, 19 Apr 2023 17:56:59 +0800
From: Tiezhu Yang <yangtiezhu@...ngson.cn>
To: Huacai Chen <chenhuacai@...nel.org>,
WANG Xuerui <kernel@...0n.name>
Cc: loongarch@...ts.linux.dev, linux-kernel@...r.kernel.org,
loongson-kernel@...ts.loongnix.cn
Subject: [PATCH v3 4/6] LoongArch: Add uprobes support
Uprobes is the user-space counterpart to kprobes, this commit
adds uprobes support for LoongArch.
Here is a simple example with CONFIG_UPROBE_EVENTS=y:
# cat test.c
#include <stdio.h>
int add(int a, int b)
{
return a + b;
}
int main()
{
return add(2, 7);
}
# gcc test.c -o /tmp/test
# nm /tmp/test | grep add
0000000120004194 T add
# cd /sys/kernel/debug/tracing
# echo > uprobe_events
# echo "p:myuprobe /tmp/test:0x4194 %r4 %r5" > uprobe_events
# echo "r:myuretprobe /tmp/test:0x4194 %r4" >> uprobe_events
# echo 1 > events/uprobes/enable
# echo 1 > tracing_on
# /tmp/test
# cat trace
...
# TASK-PID CPU# ||||| TIMESTAMP FUNCTION
# | | | ||||| | |
test-1060 [001] DNZff 1015.770620: myuprobe: (0x120004194) arg1=0x2 arg2=0x7
test-1060 [001] DNZff 1015.770930: myuretprobe: (0x1200041f0 <- 0x120004194) arg1=0x9
Signed-off-by: Tiezhu Yang <yangtiezhu@...ngson.cn>
---
arch/loongarch/Kconfig | 3 +
arch/loongarch/include/asm/uprobes.h | 36 +++++++++
arch/loongarch/kernel/Makefile | 1 +
arch/loongarch/kernel/traps.c | 9 +--
arch/loongarch/kernel/uprobes.c | 142 +++++++++++++++++++++++++++++++++++
5 files changed, 186 insertions(+), 5 deletions(-)
create mode 100644 arch/loongarch/include/asm/uprobes.h
create mode 100644 arch/loongarch/kernel/uprobes.c
diff --git a/arch/loongarch/Kconfig b/arch/loongarch/Kconfig
index 7fd5125..ab66ad2 100644
--- a/arch/loongarch/Kconfig
+++ b/arch/loongarch/Kconfig
@@ -574,6 +574,9 @@ config ARCH_MMAP_RND_BITS_MIN
config ARCH_MMAP_RND_BITS_MAX
default 18
+config ARCH_SUPPORTS_UPROBES
+ def_bool y
+
menu "Power management options"
config ARCH_SUSPEND_POSSIBLE
diff --git a/arch/loongarch/include/asm/uprobes.h b/arch/loongarch/include/asm/uprobes.h
new file mode 100644
index 0000000..59e2683
--- /dev/null
+++ b/arch/loongarch/include/asm/uprobes.h
@@ -0,0 +1,36 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+#ifndef __ASM_LOONGARCH_UPROBES_H
+#define __ASM_LOONGARCH_UPROBES_H
+
+#include <asm/inst.h>
+
+typedef u32 uprobe_opcode_t;
+
+#define MAX_UINSN_BYTES 8
+#define UPROBE_XOL_SLOT_BYTES MAX_UINSN_BYTES
+
+#define UPROBE_XOLBP_INSN larch_insn_gen_break(BRK_UPROBE_XOLBP)
+#define UPROBE_SWBP_INSN larch_insn_gen_break(BRK_UPROBE_BP)
+#define UPROBE_SWBP_INSN_SIZE LOONGARCH_INSN_SIZE
+
+struct arch_uprobe {
+ union {
+ u32 insn[2];
+ u32 ixol[2];
+ };
+ bool simulate;
+};
+
+struct arch_uprobe_task {
+ unsigned long saved_trap_nr;
+};
+
+#ifdef CONFIG_UPROBES
+bool uprobe_breakpoint_handler(struct pt_regs *regs);
+bool uprobe_singlestep_handler(struct pt_regs *regs);
+#else /* !CONFIG_UPROBES */
+static inline bool uprobe_breakpoint_handler(struct pt_regs *regs) { return false; }
+static inline bool uprobe_singlestep_handler(struct pt_regs *regs) { return false; }
+#endif /* CONFIG_UPROBES */
+
+#endif /* __ASM_LOONGARCH_UPROBES_H */
diff --git a/arch/loongarch/kernel/Makefile b/arch/loongarch/kernel/Makefile
index 78d4e33..67b9c26 100644
--- a/arch/loongarch/kernel/Makefile
+++ b/arch/loongarch/kernel/Makefile
@@ -53,5 +53,6 @@ obj-$(CONFIG_PERF_EVENTS) += perf_event.o perf_regs.o
obj-$(CONFIG_HAVE_HW_BREAKPOINT) += hw_breakpoint.o
obj-$(CONFIG_KPROBES) += kprobes.o kprobes_trampoline.o
+obj-$(CONFIG_UPROBES) += uprobes.o
CPPFLAGS_vmlinux.lds := $(KBUILD_CFLAGS)
diff --git a/arch/loongarch/kernel/traps.c b/arch/loongarch/kernel/traps.c
index de8ebe2..cfc2e0c 100644
--- a/arch/loongarch/kernel/traps.c
+++ b/arch/loongarch/kernel/traps.c
@@ -45,6 +45,7 @@
#include <asm/tlb.h>
#include <asm/types.h>
#include <asm/unwind.h>
+#include <asm/uprobes.h>
#include "access-helper.h"
@@ -440,7 +441,6 @@ asmlinkage void noinstr do_bp(struct pt_regs *regs)
if (regs->csr_prmd & CSR_PRMD_PIE)
local_irq_enable();
- current->thread.trap_nr = read_csr_excode();
if (__get_inst(&opcode, (u32 *)era, user))
goto out_sigsegv;
@@ -462,18 +462,17 @@ asmlinkage void noinstr do_bp(struct pt_regs *regs)
else
break;
case BRK_UPROBE_BP:
- if (notify_die(DIE_UPROBE, "Uprobe", regs, bcode,
- current->thread.trap_nr, SIGTRAP) == NOTIFY_STOP)
+ if (uprobe_breakpoint_handler(regs))
goto out;
else
break;
case BRK_UPROBE_XOLBP:
- if (notify_die(DIE_UPROBE_XOL, "Uprobe_XOL", regs, bcode,
- current->thread.trap_nr, SIGTRAP) == NOTIFY_STOP)
+ if (uprobe_singlestep_handler(regs))
goto out;
else
break;
default:
+ current->thread.trap_nr = read_csr_excode();
if (notify_die(DIE_TRAP, "Break", regs, bcode,
current->thread.trap_nr, SIGTRAP) == NOTIFY_STOP)
goto out;
diff --git a/arch/loongarch/kernel/uprobes.c b/arch/loongarch/kernel/uprobes.c
new file mode 100644
index 0000000..628c39d
--- /dev/null
+++ b/arch/loongarch/kernel/uprobes.c
@@ -0,0 +1,142 @@
+// SPDX-License-Identifier: GPL-2.0-only
+#include <linux/highmem.h>
+#include <linux/ptrace.h>
+#include <linux/uprobes.h>
+#include <linux/sched.h>
+#include <asm/cacheflush.h>
+
+#define UPROBE_TRAP_NR UINT_MAX
+
+int arch_uprobe_analyze_insn(struct arch_uprobe *auprobe,
+ struct mm_struct *mm, unsigned long addr)
+{
+ union loongarch_instruction insn;
+
+ if (addr & 0x3)
+ return -EILSEQ;
+
+ insn.word = auprobe->insn[0];
+
+ if (insns_not_supported(insn))
+ return -EINVAL;
+
+ if (insns_need_simulation(insn)) {
+ auprobe->ixol[0] = larch_insn_gen_nop();
+ auprobe->simulate = true;
+ } else {
+ auprobe->ixol[0] = auprobe->insn[0];
+ auprobe->simulate = false;
+ }
+
+ auprobe->ixol[1] = UPROBE_XOLBP_INSN;
+
+ return 0;
+}
+
+int arch_uprobe_pre_xol(struct arch_uprobe *auprobe, struct pt_regs *regs)
+{
+ struct uprobe_task *utask = current->utask;
+
+ utask->autask.saved_trap_nr = current->thread.trap_nr;
+ current->thread.trap_nr = UPROBE_TRAP_NR;
+ instruction_pointer_set(regs, utask->xol_vaddr);
+
+ return 0;
+}
+
+int arch_uprobe_post_xol(struct arch_uprobe *auprobe, struct pt_regs *regs)
+{
+ struct uprobe_task *utask = current->utask;
+
+ WARN_ON_ONCE(current->thread.trap_nr != UPROBE_TRAP_NR);
+ current->thread.trap_nr = utask->autask.saved_trap_nr;
+ instruction_pointer_set(regs, utask->vaddr + LOONGARCH_INSN_SIZE);
+
+ return 0;
+}
+
+void arch_uprobe_abort_xol(struct arch_uprobe *auprobe, struct pt_regs *regs)
+{
+ struct uprobe_task *utask = current->utask;
+
+ current->thread.trap_nr = utask->autask.saved_trap_nr;
+ instruction_pointer_set(regs, utask->vaddr);
+}
+
+bool arch_uprobe_xol_was_trapped(struct task_struct *t)
+{
+ if (t->thread.trap_nr != UPROBE_TRAP_NR)
+ return true;
+
+ return false;
+}
+
+bool arch_uprobe_skip_sstep(struct arch_uprobe *auprobe, struct pt_regs *regs)
+{
+ union loongarch_instruction insn;
+
+ if (!auprobe->simulate)
+ return false;
+
+ insn.word = auprobe->insn[0];
+ arch_simulate_insn(insn, regs);
+
+ return true;
+}
+
+unsigned long arch_uretprobe_hijack_return_addr(unsigned long trampoline_vaddr,
+ struct pt_regs *regs)
+{
+ unsigned long ra = regs->regs[1];
+
+ regs->regs[1] = trampoline_vaddr;
+
+ return ra;
+}
+
+bool arch_uretprobe_is_alive(struct return_instance *ret,
+ enum rp_check ctx, struct pt_regs *regs)
+{
+ if (ctx == RP_CHECK_CHAIN_CALL)
+ return regs->regs[3] <= ret->stack;
+ else
+ return regs->regs[3] < ret->stack;
+}
+
+int arch_uprobe_exception_notify(struct notifier_block *self,
+ unsigned long val, void *data)
+{
+ return NOTIFY_DONE;
+}
+
+bool uprobe_breakpoint_handler(struct pt_regs *regs)
+{
+ if (uprobe_pre_sstep_notifier(regs))
+ return true;
+
+ return false;
+}
+
+bool uprobe_singlestep_handler(struct pt_regs *regs)
+{
+ if (uprobe_post_sstep_notifier(regs))
+ return true;
+
+ return false;
+}
+
+unsigned long uprobe_get_swbp_addr(struct pt_regs *regs)
+{
+ return instruction_pointer(regs);
+}
+
+void arch_uprobe_copy_ixol(struct page *page, unsigned long vaddr,
+ void *src, unsigned long len)
+{
+ void *kaddr = kmap_local_page(page);
+ void *dst = kaddr + (vaddr & ~PAGE_MASK);
+
+ memcpy(dst, src, len);
+ flush_icache_range((unsigned long)dst, (unsigned long)dst + len);
+ kunmap_local(kaddr);
+}
--
2.1.0
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