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Subject[PATCH v10 05/12] arm64: rethook: Add arm64 rethook implementation
Date
Add rethook arm64 implementation. Most of the code has been copied from
kretprobes on arm64.

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
---
Changes in v10:
- Add a dummy @mcount to arch_rethook_prepare().
Changes in v5:
- Add description.
- Fix build error if !CONFIG_KRETPROBES
---
arch/arm64/Kconfig | 1
arch/arm64/include/asm/stacktrace.h | 2 -
arch/arm64/kernel/probes/Makefile | 1
arch/arm64/kernel/probes/rethook.c | 25 +++++++
arch/arm64/kernel/probes/rethook_trampoline.S | 87 +++++++++++++++++++++++++
arch/arm64/kernel/stacktrace.c | 7 ++
6 files changed, 121 insertions(+), 2 deletions(-)
create mode 100644 arch/arm64/kernel/probes/rethook.c
create mode 100644 arch/arm64/kernel/probes/rethook_trampoline.S

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 6978140edfa4..f098ff3b2273 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -201,6 +201,7 @@ config ARM64
select HAVE_SYSCALL_TRACEPOINTS
select HAVE_KPROBES
select HAVE_KRETPROBES
+ select HAVE_RETHOOK
select HAVE_GENERIC_VDSO
select IOMMU_DMA if IOMMU_SUPPORT
select IRQ_DOMAIN
diff --git a/arch/arm64/include/asm/stacktrace.h b/arch/arm64/include/asm/stacktrace.h
index e77cdef9ca29..bf04107da97c 100644
--- a/arch/arm64/include/asm/stacktrace.h
+++ b/arch/arm64/include/asm/stacktrace.h
@@ -58,7 +58,7 @@ struct stackframe {
DECLARE_BITMAP(stacks_done, __NR_STACK_TYPES);
unsigned long prev_fp;
enum stack_type prev_type;
-#ifdef CONFIG_KRETPROBES
+#if defined(CONFIG_KRETPROBES) || defined(CONFIG_RETHOOK)
struct llist_node *kr_cur;
#endif
};
diff --git a/arch/arm64/kernel/probes/Makefile b/arch/arm64/kernel/probes/Makefile
index 8e4be92e25b1..24e689f44c32 100644
--- a/arch/arm64/kernel/probes/Makefile
+++ b/arch/arm64/kernel/probes/Makefile
@@ -4,3 +4,4 @@ obj-$(CONFIG_KPROBES) += kprobes.o decode-insn.o \
simulate-insn.o
obj-$(CONFIG_UPROBES) += uprobes.o decode-insn.o \
simulate-insn.o
+obj-$(CONFIG_RETHOOK) += rethook.o rethook_trampoline.o
diff --git a/arch/arm64/kernel/probes/rethook.c b/arch/arm64/kernel/probes/rethook.c
new file mode 100644
index 000000000000..edc6b804ad6a
--- /dev/null
+++ b/arch/arm64/kernel/probes/rethook.c
@@ -0,0 +1,25 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Generic return hook for arm64.
+ * Most of the code is copied from arch/arm64/kernel/probes/kprobes.c
+ */
+
+#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->regs[29]);
+}
+NOKPROBE_SYMBOL(arch_rethook_trampoline_callback);
+
+void arch_rethook_prepare(struct rethook_node *rhn, struct pt_regs *regs, bool mcount)
+{
+ rhn->ret_addr = regs->regs[30];
+ rhn->frame = regs->regs[29];
+
+ /* replace return addr (x30) with trampoline */
+ regs->regs[30] = (u64)arch_rethook_trampoline;
+}
+NOKPROBE_SYMBOL(arch_rethook_prepare);
diff --git a/arch/arm64/kernel/probes/rethook_trampoline.S b/arch/arm64/kernel/probes/rethook_trampoline.S
new file mode 100644
index 000000000000..610f520ee72b
--- /dev/null
+++ b/arch/arm64/kernel/probes/rethook_trampoline.S
@@ -0,0 +1,87 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * trampoline entry and return code for rethook.
+ * Copied from arch/arm64/kernel/probes/kprobes_trampoline.S
+ */
+
+#include <linux/linkage.h>
+#include <asm/asm-offsets.h>
+#include <asm/assembler.h>
+
+ .text
+
+ .macro save_all_base_regs
+ stp x0, x1, [sp, #S_X0]
+ stp x2, x3, [sp, #S_X2]
+ stp x4, x5, [sp, #S_X4]
+ stp x6, x7, [sp, #S_X6]
+ stp x8, x9, [sp, #S_X8]
+ stp x10, x11, [sp, #S_X10]
+ stp x12, x13, [sp, #S_X12]
+ stp x14, x15, [sp, #S_X14]
+ stp x16, x17, [sp, #S_X16]
+ stp x18, x19, [sp, #S_X18]
+ stp x20, x21, [sp, #S_X20]
+ stp x22, x23, [sp, #S_X22]
+ stp x24, x25, [sp, #S_X24]
+ stp x26, x27, [sp, #S_X26]
+ stp x28, x29, [sp, #S_X28]
+ add x0, sp, #PT_REGS_SIZE
+ stp lr, x0, [sp, #S_LR]
+ /*
+ * Construct a useful saved PSTATE
+ */
+ mrs x0, nzcv
+ mrs x1, daif
+ orr x0, x0, x1
+ mrs x1, CurrentEL
+ orr x0, x0, x1
+ mrs x1, SPSel
+ orr x0, x0, x1
+ stp xzr, x0, [sp, #S_PC]
+ .endm
+
+ .macro restore_all_base_regs
+ ldr x0, [sp, #S_PSTATE]
+ and x0, x0, #(PSR_N_BIT | PSR_Z_BIT | PSR_C_BIT | PSR_V_BIT)
+ msr nzcv, x0
+ ldp x0, x1, [sp, #S_X0]
+ ldp x2, x3, [sp, #S_X2]
+ ldp x4, x5, [sp, #S_X4]
+ ldp x6, x7, [sp, #S_X6]
+ ldp x8, x9, [sp, #S_X8]
+ ldp x10, x11, [sp, #S_X10]
+ ldp x12, x13, [sp, #S_X12]
+ ldp x14, x15, [sp, #S_X14]
+ ldp x16, x17, [sp, #S_X16]
+ ldp x18, x19, [sp, #S_X18]
+ ldp x20, x21, [sp, #S_X20]
+ ldp x22, x23, [sp, #S_X22]
+ ldp x24, x25, [sp, #S_X24]
+ ldp x26, x27, [sp, #S_X26]
+ ldp x28, x29, [sp, #S_X28]
+ .endm
+
+SYM_CODE_START(arch_rethook_trampoline)
+ sub sp, sp, #PT_REGS_SIZE
+
+ save_all_base_regs
+
+ /* Setup a frame pointer. */
+ add x29, sp, #S_FP
+
+ mov x0, sp
+ bl arch_rethook_trampoline_callback
+ /*
+ * Replace trampoline address in lr with actual orig_ret_addr return
+ * address.
+ */
+ mov lr, x0
+
+ /* The frame pointer (x29) is restored with other registers. */
+ restore_all_base_regs
+
+ add sp, sp, #PT_REGS_SIZE
+ ret
+
+SYM_CODE_END(arch_rethook_trampoline)
diff --git a/arch/arm64/kernel/stacktrace.c b/arch/arm64/kernel/stacktrace.c
index 0fb58fed54cb..821c4b90fe44 100644
--- a/arch/arm64/kernel/stacktrace.c
+++ b/arch/arm64/kernel/stacktrace.c
@@ -8,6 +8,7 @@
#include <linux/export.h>
#include <linux/ftrace.h>
#include <linux/kprobes.h>
+#include <linux/rethook.h>
#include <linux/sched.h>
#include <linux/sched/debug.h>
#include <linux/sched/task_stack.h>
@@ -38,7 +39,7 @@ static void start_backtrace(struct stackframe *frame, unsigned long fp,
{
frame->fp = fp;
frame->pc = pc;
-#ifdef CONFIG_KRETPROBES
+#if defined(CONFIG_KRETPROBES) || defined(CONFIG_RETHOOK)
frame->kr_cur = NULL;
#endif

@@ -137,6 +138,10 @@ static int notrace unwind_frame(struct task_struct *tsk,
if (is_kretprobe_trampoline(frame->pc))
frame->pc = kretprobe_find_ret_addr(tsk, (void *)frame->fp, &frame->kr_cur);
#endif
+#ifdef CONFIG_RETHOOK
+ if (is_rethook_trampoline(frame->pc))
+ frame->pc = rethook_find_ret_addr(tsk, frame->fp, &frame->kr_cur);
+#endif

return 0;
}
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