[PATCH] rethook: add riscv rethook implementation.

[Binglei Wang <wang.binglei@h3c.com>]

From: "wang.binglei" <wang.binglei@h3c.com>

Most of the code copied from
arch/riscv/kernel/probes/kprobes_trampoline.S

Signed-off-by: wang.binglei <wang.binglei@h3c.com>
---
 arch/riscv/Kconfig                            |  1 +
 arch/riscv/kernel/probes/Makefile             |  1 +
 arch/riscv/kernel/probes/kprobes.c            |  7 ++
 arch/riscv/kernel/probes/rethook.c            | 24 +++++
 arch/riscv/kernel/probes/rethook_trampoline.S | 94 +++++++++++++++++++
 5 files changed, 127 insertions(+)
 create mode 100644 arch/riscv/kernel/probes/rethook.c
 create mode 100644 arch/riscv/kernel/probes/rethook_trampoline.S

diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index ed66c31e4..c5cae0825 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -97,6 +97,7 @@ config RISCV
        select HAVE_KPROBES if !XIP_KERNEL
        select HAVE_KPROBES_ON_FTRACE if !XIP_KERNEL
        select HAVE_KRETPROBES if !XIP_KERNEL
+       select HAVE_RETHOOK if !XIP_KERNEL
        select HAVE_MOVE_PMD
        select HAVE_MOVE_PUD
        select HAVE_PCI
diff --git a/arch/riscv/kernel/probes/Makefile b/arch/riscv/kernel/probes/Makefile
index 7f0840dcc..ee345e7e9 100644
--- a/arch/riscv/kernel/probes/Makefile
+++ b/arch/riscv/kernel/probes/Makefile
@@ -3,4 +3,5 @@ obj-$(CONFIG_KPROBES)           += kprobes.o decode-insn.o simulate-insn.o
 obj-$(CONFIG_KPROBES)          += kprobes_trampoline.o
 obj-$(CONFIG_KPROBES_ON_FTRACE)        += ftrace.o
 obj-$(CONFIG_UPROBES)          += uprobes.o decode-insn.o simulate-insn.o
+obj-$(CONFIG_RETHOOK)          += rethook.o rethook_trampoline.o
 CFLAGS_REMOVE_simulate-insn.o = $(CC_FLAGS_FTRACE)
diff --git a/arch/riscv/kernel/probes/kprobes.c b/arch/riscv/kernel/probes/kprobes.c
index e6e950b7c..2c1847921 100644
--- a/arch/riscv/kernel/probes/kprobes.c
+++ b/arch/riscv/kernel/probes/kprobes.c
@@ -345,6 +345,7 @@ int __init arch_populate_kprobe_blacklist(void)
        return ret;
 }

+#ifndef CONFIG_KRETPROBE_ON_RETHOOK
 void __kprobes __used *trampoline_probe_handler(struct pt_regs *regs)
 {
        return (void *)kretprobe_trampoline_handler(regs, NULL);
@@ -357,6 +358,12 @@ void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri,
        ri->fp = NULL;
        regs->ra = (unsigned long) &__kretprobe_trampoline;
 }
+#else
+void __kprobes *trampoline_probe_handler(struct pt_regs *regs)
+{
+       return NULL;
+}
+#endif

 int __kprobes arch_trampoline_kprobe(struct kprobe *p)
 {
diff --git a/arch/riscv/kernel/probes/rethook.c b/arch/riscv/kernel/probes/rethook.c
new file mode 100644
index 000000000..47853bc36
--- /dev/null
+++ b/arch/riscv/kernel/probes/rethook.c
@@ -0,0 +1,24 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Generic return hook for riscv.
+ */
+
+#include <linux/kprobes.h>
+#include <linux/rethook.h>
+
+/* This is called from arch_rethook_trampoline() */
+unsigned long __used arch_rethook_trampoline_callback(struct pt_regs *regs)
+{
+       return rethook_trampoline_handler(regs, regs->s0);
+}
+NOKPROBE_SYMBOL(arch_rethook_trampoline_callback);
+
+void arch_rethook_prepare(struct rethook_node *rhn, struct pt_regs *regs, bool mcount)
+{
+       rhn->ret_addr = regs->ra;
+       rhn->frame = regs->s0;
+
+       /* replace return addr with trampoline */
+       regs->ra = (u64)arch_rethook_trampoline;
+}
+NOKPROBE_SYMBOL(arch_rethook_prepare);
diff --git a/arch/riscv/kernel/probes/rethook_trampoline.S b/arch/riscv/kernel/probes/rethook_trampoline.S
new file mode 100644
index 000000000..aa79630ac
--- /dev/null
+++ b/arch/riscv/kernel/probes/rethook_trampoline.S
@@ -0,0 +1,94 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * rethook trampoline.
+ * Copied from arch/riscv/kernel/probes/kprobes_trampoline.S
+ */
+#include <linux/linkage.h>
+
+#include <asm/asm.h>
+#include <asm/asm-offsets.h>
+
+       .text
+       .altmacro
+
+       .macro save_all_base_regs
+       REG_S x1,  PT_RA(sp)
+       REG_S x3,  PT_GP(sp)
+       REG_S x4,  PT_TP(sp)
+       REG_S x5,  PT_T0(sp)
+       REG_S x6,  PT_T1(sp)
+       REG_S x7,  PT_T2(sp)
+       REG_S x8,  PT_S0(sp)
+       REG_S x9,  PT_S1(sp)
+       REG_S x10, PT_A0(sp)
+       REG_S x11, PT_A1(sp)
+       REG_S x12, PT_A2(sp)
+       REG_S x13, PT_A3(sp)
+       REG_S x14, PT_A4(sp)
+       REG_S x15, PT_A5(sp)
+       REG_S x16, PT_A6(sp)
+       REG_S x17, PT_A7(sp)
+       REG_S x18, PT_S2(sp)
+       REG_S x19, PT_S3(sp)
+       REG_S x20, PT_S4(sp)
+       REG_S x21, PT_S5(sp)
+       REG_S x22, PT_S6(sp)
+       REG_S x23, PT_S7(sp)
+       REG_S x24, PT_S8(sp)
+       REG_S x25, PT_S9(sp)
+       REG_S x26, PT_S10(sp)
+       REG_S x27, PT_S11(sp)
+       REG_S x28, PT_T3(sp)
+       REG_S x29, PT_T4(sp)
+       REG_S x30, PT_T5(sp)
+       REG_S x31, PT_T6(sp)
+       .endm
+
+       .macro restore_all_base_regs
+       REG_L x3,  PT_GP(sp)
+       REG_L x4,  PT_TP(sp)
+       REG_L x5,  PT_T0(sp)
+       REG_L x6,  PT_T1(sp)
+       REG_L x7,  PT_T2(sp)
+       REG_L x8,  PT_S0(sp)
+       REG_L x9,  PT_S1(sp)
+       REG_L x10, PT_A0(sp)
+       REG_L x11, PT_A1(sp)
+       REG_L x12, PT_A2(sp)
+       REG_L x13, PT_A3(sp)
+       REG_L x14, PT_A4(sp)
+       REG_L x15, PT_A5(sp)
+       REG_L x16, PT_A6(sp)
+       REG_L x17, PT_A7(sp)
+       REG_L x18, PT_S2(sp)
+       REG_L x19, PT_S3(sp)
+       REG_L x20, PT_S4(sp)
+       REG_L x21, PT_S5(sp)
+       REG_L x22, PT_S6(sp)
+       REG_L x23, PT_S7(sp)
+       REG_L x24, PT_S8(sp)
+       REG_L x25, PT_S9(sp)
+       REG_L x26, PT_S10(sp)
+       REG_L x27, PT_S11(sp)
+       REG_L x28, PT_T3(sp)
+       REG_L x29, PT_T4(sp)
+       REG_L x30, PT_T5(sp)
+       REG_L x31, PT_T6(sp)
+       .endm
+
+ENTRY(arch_rethook_trampoline)
+       addi sp, sp, -(PT_SIZE_ON_STACK)
+       save_all_base_regs
+
+       move a0, sp /* pt_regs */
+
+       call arch_rethook_trampoline_callback
+
+       /* use the result as the return-address */
+       move ra, a0
+
+       restore_all_base_regs
+       addi sp, sp, PT_SIZE_ON_STACK
+
+       ret
+ENDPROC(arch_rethook_trampoline)
--
2.17.1

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