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Message-Id: <164821819583.2373735.12533617295328678018.stgit@devnote2>
Date: Fri, 25 Mar 2022 23:23:16 +0900
From: Masami Hiramatsu <mhiramat@...nel.org>
To: Alexei Starovoitov <ast@...nel.org>,
Andrii Nakryiko <andrii.nakryiko@...il.com>, x86@...nel.org,
Peter Zijlstra <peterz@...radead.org>
Cc: Thomas Gleixner <tglx@...utronix.de>,
Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
Dave Hansen <dave.hansen@...ux.intel.com>,
Dan Carpenter <dan.carpenter@...cle.com>,
kernel-janitors@...r.kernel.org,
Steven Rostedt <rostedt@...dmis.org>,
Masami Hiramatsu <mhiramat@...nel.org>,
Jiri Olsa <jolsa@...nel.org>, bpf@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: [PATCH bpf-next v2 2/4] rethook: kprobes: x86: Replace kretprobe with rethook on x86
Replaces the kretprobe code with rethook on x86. With this patch,
kretprobe on x86 uses the rethook instead of kretprobe specific
trampoline code.
Signed-off-by: Masami Hiramatsu <mhiramat@...nel.org>
Tested-by: Jiri Olsa <jolsa@...nel.org>
---
Changes in v2:
- Fix remaining unwind_recover_kretprobe() with unwind_recover_rethook()
(Thanks Peter!)
- Replace remaining "kretprobe" with "rethook" in comment.
---
arch/x86/Kconfig | 1
arch/x86/include/asm/unwind.h | 23 +++----
arch/x86/kernel/Makefile | 1
arch/x86/kernel/kprobes/common.h | 1
arch/x86/kernel/kprobes/core.c | 107 ----------------------------------
arch/x86/kernel/rethook.c | 121 ++++++++++++++++++++++++++++++++++++++
arch/x86/kernel/unwind_orc.c | 10 ++-
7 files changed, 140 insertions(+), 124 deletions(-)
create mode 100644 arch/x86/kernel/rethook.c
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index db3bedcbf6be..e85b52a6f612 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -224,6 +224,7 @@ config X86
select HAVE_KPROBES_ON_FTRACE
select HAVE_FUNCTION_ERROR_INJECTION
select HAVE_KRETPROBES
+ select HAVE_RETHOOK
select HAVE_KVM
select HAVE_LIVEPATCH if X86_64
select HAVE_MIXED_BREAKPOINTS_REGS
diff --git a/arch/x86/include/asm/unwind.h b/arch/x86/include/asm/unwind.h
index 2a1f8734416d..7cede4dc21f0 100644
--- a/arch/x86/include/asm/unwind.h
+++ b/arch/x86/include/asm/unwind.h
@@ -4,7 +4,7 @@
#include <linux/sched.h>
#include <linux/ftrace.h>
-#include <linux/kprobes.h>
+#include <linux/rethook.h>
#include <asm/ptrace.h>
#include <asm/stacktrace.h>
@@ -16,7 +16,7 @@ struct unwind_state {
unsigned long stack_mask;
struct task_struct *task;
int graph_idx;
-#ifdef CONFIG_KRETPROBES
+#if defined(CONFIG_RETHOOK)
struct llist_node *kr_cur;
#endif
bool error;
@@ -104,19 +104,18 @@ void unwind_module_init(struct module *mod, void *orc_ip, size_t orc_ip_size,
#endif
static inline
-unsigned long unwind_recover_kretprobe(struct unwind_state *state,
- unsigned long addr, unsigned long *addr_p)
+unsigned long unwind_recover_rethook(struct unwind_state *state,
+ unsigned long addr, unsigned long *addr_p)
{
-#ifdef CONFIG_KRETPROBES
- return is_kretprobe_trampoline(addr) ?
- kretprobe_find_ret_addr(state->task, addr_p, &state->kr_cur) :
- addr;
-#else
- return addr;
+#ifdef CONFIG_RETHOOK
+ if (is_rethook_trampoline(addr))
+ return rethook_find_ret_addr(state->task, (unsigned long)addr_p,
+ &state->kr_cur);
#endif
+ return addr;
}
-/* Recover the return address modified by kretprobe and ftrace_graph. */
+/* Recover the return address modified by rethook and ftrace_graph. */
static inline
unsigned long unwind_recover_ret_addr(struct unwind_state *state,
unsigned long addr, unsigned long *addr_p)
@@ -125,7 +124,7 @@ unsigned long unwind_recover_ret_addr(struct unwind_state *state,
ret = ftrace_graph_ret_addr(state->task, &state->graph_idx,
addr, addr_p);
- return unwind_recover_kretprobe(state, ret, addr_p);
+ return unwind_recover_rethook(state, ret, addr_p);
}
/*
diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile
index 6462e3dd98f4..c41ef42adbe8 100644
--- a/arch/x86/kernel/Makefile
+++ b/arch/x86/kernel/Makefile
@@ -103,6 +103,7 @@ obj-$(CONFIG_FUNCTION_GRAPH_TRACER) += ftrace.o
obj-$(CONFIG_FTRACE_SYSCALLS) += ftrace.o
obj-$(CONFIG_X86_TSC) += trace_clock.o
obj-$(CONFIG_TRACING) += trace.o
+obj-$(CONFIG_RETHOOK) += rethook.o
obj-$(CONFIG_CRASH_CORE) += crash_core_$(BITS).o
obj-$(CONFIG_KEXEC_CORE) += machine_kexec_$(BITS).o
obj-$(CONFIG_KEXEC_CORE) += relocate_kernel_$(BITS).o crash.o
diff --git a/arch/x86/kernel/kprobes/common.h b/arch/x86/kernel/kprobes/common.h
index 7d3a2e2daf01..c993521d4933 100644
--- a/arch/x86/kernel/kprobes/common.h
+++ b/arch/x86/kernel/kprobes/common.h
@@ -6,6 +6,7 @@
#include <asm/asm.h>
#include <asm/frame.h>
+#include <asm/insn.h>
#ifdef CONFIG_X86_64
diff --git a/arch/x86/kernel/kprobes/core.c b/arch/x86/kernel/kprobes/core.c
index 8ef933c03afa..7c4ab8870da4 100644
--- a/arch/x86/kernel/kprobes/core.c
+++ b/arch/x86/kernel/kprobes/core.c
@@ -811,18 +811,6 @@ set_current_kprobe(struct kprobe *p, struct pt_regs *regs,
= (regs->flags & X86_EFLAGS_IF);
}
-void arch_prepare_kretprobe(struct kretprobe_instance *ri, struct pt_regs *regs)
-{
- unsigned long *sara = stack_addr(regs);
-
- ri->ret_addr = (kprobe_opcode_t *) *sara;
- ri->fp = sara;
-
- /* Replace the return addr with trampoline addr */
- *sara = (unsigned long) &__kretprobe_trampoline;
-}
-NOKPROBE_SYMBOL(arch_prepare_kretprobe);
-
static void kprobe_post_process(struct kprobe *cur, struct pt_regs *regs,
struct kprobe_ctlblk *kcb)
{
@@ -1023,101 +1011,6 @@ int kprobe_int3_handler(struct pt_regs *regs)
}
NOKPROBE_SYMBOL(kprobe_int3_handler);
-/*
- * When a retprobed function returns, this code saves registers and
- * calls trampoline_handler() runs, which calls the kretprobe's handler.
- */
-asm(
- ".text\n"
- ".global __kretprobe_trampoline\n"
- ".type __kretprobe_trampoline, @function\n"
- "__kretprobe_trampoline:\n"
-#ifdef CONFIG_X86_64
- ANNOTATE_NOENDBR
- /* Push a fake return address to tell the unwinder it's a kretprobe. */
- " pushq $__kretprobe_trampoline\n"
- UNWIND_HINT_FUNC
- /* Save the 'sp - 8', this will be fixed later. */
- " pushq %rsp\n"
- " pushfq\n"
- SAVE_REGS_STRING
- " movq %rsp, %rdi\n"
- " call trampoline_handler\n"
- RESTORE_REGS_STRING
- /* In trampoline_handler(), 'regs->flags' is copied to 'regs->sp'. */
- " addq $8, %rsp\n"
- " popfq\n"
-#else
- /* Push a fake return address to tell the unwinder it's a kretprobe. */
- " pushl $__kretprobe_trampoline\n"
- UNWIND_HINT_FUNC
- /* Save the 'sp - 4', this will be fixed later. */
- " pushl %esp\n"
- " pushfl\n"
- SAVE_REGS_STRING
- " movl %esp, %eax\n"
- " call trampoline_handler\n"
- RESTORE_REGS_STRING
- /* In trampoline_handler(), 'regs->flags' is copied to 'regs->sp'. */
- " addl $4, %esp\n"
- " popfl\n"
-#endif
- ASM_RET
- ".size __kretprobe_trampoline, .-__kretprobe_trampoline\n"
-);
-NOKPROBE_SYMBOL(__kretprobe_trampoline);
-/*
- * __kretprobe_trampoline() skips updating frame pointer. The frame pointer
- * saved in trampoline_handler() points to the real caller function's
- * frame pointer. Thus the __kretprobe_trampoline() doesn't have a
- * standard stack frame with CONFIG_FRAME_POINTER=y.
- * Let's mark it non-standard function. Anyway, FP unwinder can correctly
- * unwind without the hint.
- */
-STACK_FRAME_NON_STANDARD_FP(__kretprobe_trampoline);
-
-/* This is called from kretprobe_trampoline_handler(). */
-void arch_kretprobe_fixup_return(struct pt_regs *regs,
- kprobe_opcode_t *correct_ret_addr)
-{
- unsigned long *frame_pointer = ®s->sp + 1;
-
- /* Replace fake return address with real one. */
- *frame_pointer = (unsigned long)correct_ret_addr;
-}
-
-/*
- * Called from __kretprobe_trampoline
- */
-__used __visible void trampoline_handler(struct pt_regs *regs)
-{
- unsigned long *frame_pointer;
-
- /* fixup registers */
- regs->cs = __KERNEL_CS;
-#ifdef CONFIG_X86_32
- regs->gs = 0;
-#endif
- regs->ip = (unsigned long)&__kretprobe_trampoline;
- regs->orig_ax = ~0UL;
- regs->sp += sizeof(long);
- frame_pointer = ®s->sp + 1;
-
- /*
- * The return address at 'frame_pointer' is recovered by the
- * arch_kretprobe_fixup_return() which called from the
- * kretprobe_trampoline_handler().
- */
- kretprobe_trampoline_handler(regs, frame_pointer);
-
- /*
- * Copy FLAGS to 'pt_regs::sp' so that __kretprobe_trapmoline()
- * can do RET right after POPF.
- */
- regs->sp = regs->flags;
-}
-NOKPROBE_SYMBOL(trampoline_handler);
-
int kprobe_fault_handler(struct pt_regs *regs, int trapnr)
{
struct kprobe *cur = kprobe_running();
diff --git a/arch/x86/kernel/rethook.c b/arch/x86/kernel/rethook.c
new file mode 100644
index 000000000000..56275540eeea
--- /dev/null
+++ b/arch/x86/kernel/rethook.c
@@ -0,0 +1,121 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * x86 implementation of rethook. Mostly copied from arch/x86/kernel/kprobes/core.c.
+ */
+#include <linux/bug.h>
+#include <linux/rethook.h>
+#include <linux/kprobes.h>
+#include <linux/objtool.h>
+
+#include "kprobes/common.h"
+
+__visible void arch_rethook_trampoline_callback(struct pt_regs *regs);
+
+/*
+ * When a target function returns, this code saves registers and calls
+ * arch_rethook_trampoline_callback(), which calls the rethook handler.
+ */
+asm(
+ ".text\n"
+ ".global arch_rethook_trampoline\n"
+ ".type arch_rethook_trampoline, @function\n"
+ "arch_rethook_trampoline:\n"
+#ifdef CONFIG_X86_64
+ ANNOTATE_NOENDBR /* This is only jumped from ret instruction */
+ /* Push a fake return address to tell the unwinder it's a rethook. */
+ " pushq $arch_rethook_trampoline\n"
+ UNWIND_HINT_FUNC
+ /* Save the 'sp - 8', this will be fixed later. */
+ " pushq %rsp\n"
+ " pushfq\n"
+ SAVE_REGS_STRING
+ " movq %rsp, %rdi\n"
+ " call arch_rethook_trampoline_callback\n"
+ RESTORE_REGS_STRING
+ /* In the callback function, 'regs->flags' is copied to 'regs->sp'. */
+ " addq $8, %rsp\n"
+ " popfq\n"
+#else
+ /* Push a fake return address to tell the unwinder it's a rethook. */
+ " pushl $arch_rethook_trampoline\n"
+ UNWIND_HINT_FUNC
+ /* Save the 'sp - 4', this will be fixed later. */
+ " pushl %esp\n"
+ " pushfl\n"
+ SAVE_REGS_STRING
+ " movl %esp, %eax\n"
+ " call arch_rethook_trampoline_callback\n"
+ RESTORE_REGS_STRING
+ /* In the callback function, 'regs->flags' is copied to 'regs->sp'. */
+ " addl $4, %esp\n"
+ " popfl\n"
+#endif
+ ASM_RET
+ ".size arch_rethook_trampoline, .-arch_rethook_trampoline\n"
+);
+NOKPROBE_SYMBOL(arch_rethook_trampoline);
+
+/*
+ * Called from arch_rethook_trampoline
+ */
+__used __visible void arch_rethook_trampoline_callback(struct pt_regs *regs)
+{
+ unsigned long *frame_pointer;
+
+ /* fixup registers */
+ regs->cs = __KERNEL_CS;
+#ifdef CONFIG_X86_32
+ regs->gs = 0;
+#endif
+ regs->ip = (unsigned long)&arch_rethook_trampoline;
+ regs->orig_ax = ~0UL;
+ regs->sp += sizeof(long);
+ frame_pointer = ®s->sp + 1;
+
+ /*
+ * The return address at 'frame_pointer' is recovered by the
+ * arch_rethook_fixup_return() which called from this
+ * rethook_trampoline_handler().
+ */
+ rethook_trampoline_handler(regs, (unsigned long)frame_pointer);
+
+ /*
+ * Copy FLAGS to 'pt_regs::sp' so that arch_rethook_trapmoline()
+ * can do RET right after POPF.
+ */
+ regs->sp = regs->flags;
+}
+NOKPROBE_SYMBOL(arch_rethook_trampoline_callback);
+
+/*
+ * arch_rethook_trampoline() skips updating frame pointer. The frame pointer
+ * saved in arch_rethook_trampoline_callback() points to the real caller
+ * function's frame pointer. Thus the arch_rethook_trampoline() doesn't have
+ * a standard stack frame with CONFIG_FRAME_POINTER=y.
+ * Let's mark it non-standard function. Anyway, FP unwinder can correctly
+ * unwind without the hint.
+ */
+STACK_FRAME_NON_STANDARD_FP(arch_rethook_trampoline);
+
+/* This is called from rethook_trampoline_handler(). */
+void arch_rethook_fixup_return(struct pt_regs *regs,
+ unsigned long correct_ret_addr)
+{
+ unsigned long *frame_pointer = ®s->sp + 1;
+
+ /* Replace fake return address with real one. */
+ *frame_pointer = correct_ret_addr;
+}
+NOKPROBE_SYMBOL(arch_rethook_fixup_return);
+
+void arch_rethook_prepare(struct rethook_node *rh, struct pt_regs *regs, bool mcount)
+{
+ unsigned long *stack = (unsigned long *)regs->sp;
+
+ rh->ret_addr = stack[0];
+ rh->frame = regs->sp;
+
+ /* Replace the return addr with trampoline addr */
+ stack[0] = (unsigned long) arch_rethook_trampoline;
+}
+NOKPROBE_SYMBOL(arch_rethook_prepare);
diff --git a/arch/x86/kernel/unwind_orc.c b/arch/x86/kernel/unwind_orc.c
index 2de3c8c5eba9..794fdef2501a 100644
--- a/arch/x86/kernel/unwind_orc.c
+++ b/arch/x86/kernel/unwind_orc.c
@@ -550,15 +550,15 @@ bool unwind_next_frame(struct unwind_state *state)
}
/*
* There is a small chance to interrupt at the entry of
- * __kretprobe_trampoline() where the ORC info doesn't exist.
- * That point is right after the RET to __kretprobe_trampoline()
+ * arch_rethook_trampoline() where the ORC info doesn't exist.
+ * That point is right after the RET to arch_rethook_trampoline()
* which was modified return address.
- * At that point, the @addr_p of the unwind_recover_kretprobe()
+ * At that point, the @addr_p of the unwind_recover_rethook()
* (this has to point the address of the stack entry storing
* the modified return address) must be "SP - (a stack entry)"
* because SP is incremented by the RET.
*/
- state->ip = unwind_recover_kretprobe(state, state->ip,
+ state->ip = unwind_recover_rethook(state, state->ip,
(unsigned long *)(state->sp - sizeof(long)));
state->regs = (struct pt_regs *)sp;
state->prev_regs = NULL;
@@ -573,7 +573,7 @@ bool unwind_next_frame(struct unwind_state *state)
goto err;
}
/* See UNWIND_HINT_TYPE_REGS case comment. */
- state->ip = unwind_recover_kretprobe(state, state->ip,
+ state->ip = unwind_recover_rethook(state, state->ip,
(unsigned long *)(state->sp - sizeof(long)));
if (state->full_regs)
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