riscv: add riscv rethook implementation

Implement the kretprobes on riscv arch by using rethook machenism
which abstracts general kretprobe info into a struct rethook_node
to be embedded in the struct kretprobe_instance.

Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Binglei Wang <l3b2w1@gmail.com>
Signed-off-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20221025151831.1097417-1-conor@kernel.org
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>

diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index 8d47562..ef8d66d 100644 (file)
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -101,6 +101,7 @@ 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/include/asm/kprobes.h b/arch/riscv/include/asm/kprobes.h
index 217ef89..e7882cc 100644 (file)
--- a/arch/riscv/include/asm/kprobes.h
+++ b/arch/riscv/include/asm/kprobes.h
@@ -40,8 +40,6 @@ void arch_remove_kprobe(struct kprobe *p);
 int kprobe_fault_handler(struct pt_regs *regs, unsigned int trapnr);
 bool kprobe_breakpoint_handler(struct pt_regs *regs);
 bool kprobe_single_step_handler(struct pt_regs *regs);
-void __kretprobe_trampoline(void);
-void __kprobes *trampoline_probe_handler(struct pt_regs *regs);
 
 #endif /* CONFIG_KPROBES */
 #endif /* _ASM_RISCV_KPROBES_H */

diff --git a/arch/riscv/kernel/probes/Makefile b/arch/riscv/kernel/probes/Makefile
index 7f0840d..c40139e 100644 (file)
--- a/arch/riscv/kernel/probes/Makefile
+++ b/arch/riscv/kernel/probes/Makefile
@@ -1,6 +1,6 @@
 # SPDX-License-Identifier: GPL-2.0
 obj-$(CONFIG_KPROBES)          += kprobes.o decode-insn.o simulate-insn.o
-obj-$(CONFIG_KPROBES)          += kprobes_trampoline.o
+obj-$(CONFIG_RETHOOK)          += rethook.o rethook_trampoline.o
 obj-$(CONFIG_KPROBES_ON_FTRACE)        += ftrace.o
 obj-$(CONFIG_UPROBES)          += uprobes.o decode-insn.o simulate-insn.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 e6e950b..f21592d 100644 (file)
--- a/arch/riscv/kernel/probes/kprobes.c
+++ b/arch/riscv/kernel/probes/kprobes.c
@@ -345,19 +345,6 @@ int __init arch_populate_kprobe_blacklist(void)
        return ret;
 }
 
-void __kprobes __used *trampoline_probe_handler(struct pt_regs *regs)
-{
-       return (void *)kretprobe_trampoline_handler(regs, NULL);
-}
-
-void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri,
-                                     struct pt_regs *regs)
-{
-       ri->ret_addr = (kprobe_opcode_t *)regs->ra;
-       ri->fp = NULL;
-       regs->ra = (unsigned long) &__kretprobe_trampoline;
-}
-
 int __kprobes arch_trampoline_kprobe(struct kprobe *p)
 {
        return 0;

diff --git a/arch/riscv/kernel/probes/rethook.c b/arch/riscv/kernel/probes/rethook.c
new file mode 100644 (file)
index 0000000..5c27c1f
--- /dev/null
+++ b/arch/riscv/kernel/probes/rethook.c
@@ -0,0 +1,27 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Generic return hook for riscv.
+ */
+
+#include <linux/kprobes.h>
+#include <linux/rethook.h>
+#include "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 = (unsigned long)arch_rethook_trampoline;
+}
+
+NOKPROBE_SYMBOL(arch_rethook_prepare);

diff --git a/arch/riscv/kernel/probes/rethook.h b/arch/riscv/kernel/probes/rethook.h
new file mode 100644 (file)
index 0000000..4758f7e
--- /dev/null
+++ b/arch/riscv/kernel/probes/rethook.h
@@ -0,0 +1,8 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+#ifndef __RISCV_RETHOOK_H
+#define __RISCV_RETHOOK_H
+
+unsigned long arch_rethook_trampoline_callback(struct pt_regs *regs);
+void arch_rethook_prepare(struct rethook_node *rhn, struct pt_regs *regs, bool mcount);
+
+#endif

diff --git a/arch/riscv/kernel/probes/kprobes_trampoline.S b/arch/riscv/kernel/probes/rethook_trampoline.S
similarity index 94%
rename from arch/riscv/kernel/probes/kprobes_trampoline.S
rename to arch/riscv/kernel/probes/rethook_trampoline.S
index 7bdb09d..21bac92 100644 (file)
--- a/arch/riscv/kernel/probes/kprobes_trampoline.S
+++ b/arch/riscv/kernel/probes/rethook_trampoline.S
@@ -75,13 +75,13 @@
        REG_L x31, PT_T6(sp)
        .endm
 
-ENTRY(__kretprobe_trampoline)
+ENTRY(arch_rethook_trampoline)
        addi sp, sp, -(PT_SIZE_ON_STACK)
        save_all_base_regs
 
        move a0, sp /* pt_regs */
 
-       call trampoline_probe_handler
+       call arch_rethook_trampoline_callback
 
        /* use the result as the return-address */
        move ra, a0
@@ -90,4 +90,4 @@ ENTRY(__kretprobe_trampoline)
        addi sp, sp, PT_SIZE_ON_STACK
 
        ret
-ENDPROC(__kretprobe_trampoline)
+ENDPROC(arch_rethook_trampoline)