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Rao" , Anil S Keshavamurthy , "David S . Miller" Subject: [PATCH v7 04/10] rethook: x86: Add rethook x86 implementation Date: Mon, 31 Jan 2022 14:01:11 +0900 Message-Id: <164360527166.65877.2210544958538596733.stgit@devnote2> X-Mailer: git-send-email 2.25.1 In-Reply-To: <164360522462.65877.1891020292202285106.stgit@devnote2> References: <164360522462.65877.1891020292202285106.stgit@devnote2> User-Agent: StGit/0.19 MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Add rethook for x86 implementation. Most of the code has been copied from kretprobes on x86. Signed-off-by: Masami Hiramatsu --- Changes in v5: - Fix a build error if !CONFIG_KRETPROBES and !CONFIG_RETHOOK. Changes in v4: - fix stack backtrace as same as kretprobe does. --- arch/x86/Kconfig | 1 arch/x86/include/asm/unwind.h | 8 ++- arch/x86/kernel/Makefile | 1 arch/x86/kernel/kprobes/common.h | 1 arch/x86/kernel/rethook.c | 115 ++++++++++++++++++++++++++++++++++++++ 5 files changed, 125 insertions(+), 1 deletion(-) create mode 100644 arch/x86/kernel/rethook.c diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index 7399327d1eff..939c4c897e63 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -219,6 +219,7 @@ 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..192df5b2094d 100644 --- a/arch/x86/include/asm/unwind.h +++ b/arch/x86/include/asm/unwind.h @@ -5,6 +5,7 @@ #include #include #include +#include #include #include @@ -16,7 +17,7 @@ struct unwind_state { unsigned long stack_mask; struct task_struct *task; int graph_idx; -#ifdef CONFIG_KRETPROBES +#if defined(CONFIG_KRETPROBES) || defined(CONFIG_RETHOOK) struct llist_node *kr_cur; #endif bool error; @@ -107,6 +108,11 @@ static inline unsigned long unwind_recover_kretprobe(struct unwind_state *state, unsigned long addr, unsigned long *addr_p) { +#ifdef CONFIG_RETHOOK + if (is_rethook_trampoline(addr)) + return rethook_find_ret_addr(state->task, (unsigned long)addr_p, + &state->kr_cur); +#endif #ifdef CONFIG_KRETPROBES return is_kretprobe_trampoline(addr) ? kretprobe_find_ret_addr(state->task, addr_p, &state->kr_cur) : diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile index 2ff3e600f426..66593d8c4d74 100644 --- a/arch/x86/kernel/Makefile +++ b/arch/x86/kernel/Makefile @@ -106,6 +106,7 @@ 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 #include +#include #ifdef CONFIG_X86_64 diff --git a/arch/x86/kernel/rethook.c b/arch/x86/kernel/rethook.c new file mode 100644 index 000000000000..f2f3b9526e43 --- /dev/null +++ b/arch/x86/kernel/rethook.c @@ -0,0 +1,115 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * x86 implementation of rethook. Mostly copied from arch/x86/kernel/kprobes/core.c. + */ +#include +#include +#include + +#include "kprobes/common.h" + +/* + * 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); + +/* + * 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 + /* Push a fake return address to tell the unwinder it's a kretprobe. */ + " 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 kretprobe. */ + " 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 + " ret\n" + ".size arch_rethook_trampoline, .-arch_rethook_trampoline\n" +); +NOKPROBE_SYMBOL(arch_rethook_trampoline); +/* + * 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; +} + +void arch_rethook_prepare(struct rethook_node *rh, struct pt_regs *regs) +{ + 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);