From: Steven Rostedt <rostedt@goodmis.org>
To: "Hou Wenlong" <houwenlong.hwl@antgroup.com>
Cc: linux-kernel@vger.kernel.org,
"Thomas Garnier" <thgarnie@chromium.org>,
"Lai Jiangshan" <jiangshan.ljs@antgroup.com>,
"Kees Cook" <keescook@chromium.org>,
"Masami Hiramatsu" <mhiramat@kernel.org>,
"Mark Rutland" <mark.rutland@arm.com>,
"Thomas Gleixner" <tglx@linutronix.de>,
"Ingo Molnar" <mingo@redhat.com>,
"Borislav Petkov" <bp@alien8.de>,
"Dave Hansen" <dave.hansen@linux.intel.com>, <x86@kernel.org>,
"H. Peter Anvin" <hpa@zytor.com>,
"Huacai Chen" <chenhuacai@kernel.org>,
"Qing Zhang" <zhangqing@loongson.cn>,
<linux-trace-kernel@vger.kernel.org>
Subject: Re: [PATCH RFC 22/43] x86/ftrace: Adapt ftrace nop patching for PIE support
Date: Fri, 28 Apr 2023 09:44:54 -0400 [thread overview]
Message-ID: <20230428094454.0f2f5049@gandalf.local.home> (raw)
In-Reply-To: <38a5029cd2590e04209117740f8912db36eff58f.1682673543.git.houwenlong.hwl@antgroup.com>
On Fri, 28 Apr 2023 17:51:02 +0800
"Hou Wenlong" <houwenlong.hwl@antgroup.com> wrote:
> From: Thomas Garnier <thgarnie@chromium.org>
>
> From: Thomas Garnier <thgarnie@chromium.org>
>
> When using PIE with function tracing, the compiler generates a
> call through the GOT (call *__fentry__@GOTPCREL). This instruction
> takes 6-bytes instead of 5-bytes with a relative call. And -mnop-mcount
> option is not implemented for -fPIE now.
>
> If PIE is enabled, replace the 6th byte of the GOT call by a 1-byte nop
> so ftrace can handle the previous 5-bytes as before.
Wait! This won't work!
You can't just append another nop to fill in the blanks here. We must
either have a single 6 byte nop, or we need to refactor the entire logic to
something that other archs have.
The two nops means that the CPU can take it as two separate commands.
There's nothing stopping the computer from preempting a task between the
two. If that happens, and you modify the 1byte nop and 5byte nop with a
single 6 byte command, when the task get's rescheduled, it will execute the
last 5 bytes of that 6 byte command and take a general protection fault, and
likely crash the machine.
NACK on this. It needs a better solution.
-- Steve
>
> [Hou Wenlong: Adapt code change and fix wrong offset calculation in
> make_nop_x86()]
>
next prev parent reply other threads:[~2023-04-28 13:45 UTC|newest]
Thread overview: 80+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-04-28 9:50 [PATCH RFC 00/43] x86/pie: Make kernel image's virtual address flexible Hou Wenlong
2023-04-28 9:50 ` [PATCH RFC 01/43] x86/crypto: Adapt assembly for PIE support Hou Wenlong
2023-04-28 9:50 ` [PATCH RFC 02/43] x86: Add macro to get symbol address " Hou Wenlong
2023-04-28 9:50 ` [PATCH RFC 03/43] x86: relocate_kernel - Adapt assembly " Hou Wenlong
2023-04-28 9:50 ` [PATCH RFC 04/43] x86/entry/64: " Hou Wenlong
2023-04-28 9:50 ` [PATCH RFC 05/43] x86: pm-trace: " Hou Wenlong
2023-04-28 9:50 ` [PATCH RFC 06/43] x86/CPU: " Hou Wenlong
2023-04-28 9:50 ` [PATCH RFC 07/43] x86/acpi: " Hou Wenlong
2023-04-28 11:32 ` Rafael J. Wysocki
2023-04-28 9:50 ` [PATCH RFC 08/43] x86/boot/64: " Hou Wenlong
2023-04-28 9:50 ` [PATCH RFC 09/43] x86/power/64: " Hou Wenlong
2023-04-28 9:50 ` [PATCH RFC 10/43] x86/alternatives: " Hou Wenlong
2023-04-28 9:50 ` [PATCH RFC 11/43] x86/irq: " Hou Wenlong
2023-04-28 9:50 ` [PATCH RFC 12/43] x86,rethook: " Hou Wenlong
2023-04-28 9:50 ` [PATCH RFC 13/43] x86/paravirt: Use relative reference for original instruction Hou Wenlong
2023-06-01 9:29 ` Juergen Gross
2023-06-01 9:29 ` Juergen Gross via Virtualization
2023-06-05 6:40 ` Nadav Amit
2023-06-05 6:40 ` Nadav Amit via Virtualization
2023-06-06 11:35 ` Hou Wenlong
2023-04-28 9:50 ` [PATCH RFC 14/43] x86/Kconfig: Introduce new Kconfig for PIE kernel building Hou Wenlong
2023-04-28 9:50 ` [PATCH RFC 15/43] x86/PVH: Use fixed_percpu_data to set up GS base Hou Wenlong
2023-04-28 9:50 ` [PATCH RFC 16/43] x86-64: Use per-cpu stack canary if supported by compiler Hou Wenlong
2023-05-01 17:27 ` Nick Desaulniers
2023-05-05 6:14 ` Hou Wenlong
2023-05-05 18:02 ` Nick Desaulniers
2023-05-05 19:06 ` Fangrui Song
2023-05-08 8:06 ` Hou Wenlong
2023-05-04 10:31 ` Juergen Gross
2023-05-05 3:09 ` Hou Wenlong
2023-04-28 9:50 ` [PATCH RFC 17/43] x86/pie: Enable stack protector only if per-cpu stack canary is supported Hou Wenlong
2023-04-28 9:50 ` [PATCH RFC 18/43] x86/percpu: Use PC-relative addressing for percpu variable references Hou Wenlong
2023-04-28 9:50 ` [PATCH RFC 19/43] x86/tools: Explicitly include autoconf.h for hostprogs Hou Wenlong
2023-04-28 9:51 ` [PATCH RFC 20/43] x86/percpu: Adapt percpu references relocation for PIE support Hou Wenlong
2023-04-28 9:51 ` [PATCH RFC 21/43] x86/ftrace: Adapt assembly " Hou Wenlong
2023-04-28 13:37 ` Steven Rostedt
2023-04-29 3:43 ` Hou Wenlong
2023-04-28 9:51 ` [PATCH RFC 22/43] x86/ftrace: Adapt ftrace nop patching " Hou Wenlong
2023-04-28 13:44 ` Steven Rostedt [this message]
2023-04-29 3:38 ` Hou Wenlong
2023-04-28 9:51 ` [PATCH RFC 23/43] x86/pie: Force hidden visibility for all symbol references Hou Wenlong
2023-04-28 9:51 ` [PATCH RFC 24/43] x86/boot/compressed: Adapt sed command to generate voffset.h when PIE is enabled Hou Wenlong
2023-04-28 9:51 ` [PATCH RFC 25/43] x86/mm: Make the x86 GOT read-only Hou Wenlong
2023-04-30 14:23 ` Ard Biesheuvel
2023-05-08 11:40 ` Hou Wenlong
2023-04-28 9:51 ` [PATCH RFC 26/43] x86/pie: Add .data.rel.* sections into link script Hou Wenlong
2023-04-28 9:51 ` [PATCH RFC 27/43] x86/relocs: Handle PIE relocations Hou Wenlong
2023-04-28 9:51 ` [PATCH RFC 28/43] KVM: x86: Adapt assembly for PIE support Hou Wenlong
2023-04-28 9:51 ` [PATCH RFC 29/43] x86/PVH: Adapt PVH booting " Hou Wenlong
2023-04-28 9:51 ` [PATCH RFC 30/43] x86/bpf: Adapt BPF_CALL JIT codegen " Hou Wenlong
2023-04-28 9:51 ` [PATCH RFC 31/43] x86/modules: Adapt module loading " Hou Wenlong
2023-04-28 19:29 ` Ard Biesheuvel
2023-05-08 8:32 ` Hou Wenlong
2023-05-08 9:16 ` Ard Biesheuvel
2023-05-08 11:40 ` Hou Wenlong
2023-05-08 17:47 ` Ard Biesheuvel
2023-05-09 9:42 ` Hou Wenlong
2023-05-09 9:52 ` Ard Biesheuvel
2023-05-09 12:35 ` Hou Wenlong
2023-05-10 7:09 ` Hou Wenlong
2023-05-10 8:15 ` Ard Biesheuvel
2023-04-28 9:51 ` [PATCH RFC 32/43] x86/boot/64: Use data relocation to get absloute address when PIE is enabled Hou Wenlong
2023-04-28 9:51 ` [PATCH RFC 33/43] objtool: Add validation for x86 PIE support Hou Wenlong
2023-04-28 10:28 ` Christophe Leroy
2023-04-28 11:43 ` Peter Zijlstra
2023-04-29 4:04 ` Hou Wenlong
2023-04-29 3:52 ` Hou Wenlong
2023-04-28 9:51 ` [PATCH RFC 34/43] objtool: Adapt indirect call of __fentry__() for " Hou Wenlong
2023-04-28 15:18 ` Peter Zijlstra
2023-04-28 9:51 ` [PATCH RFC 35/43] x86/pie: Build the kernel as PIE Hou Wenlong
2023-04-28 9:51 ` [PATCH RFC 36/43] x86/vsyscall: Don't use set_fixmap() to map vsyscall page Hou Wenlong
2023-04-28 9:51 ` [PATCH RFC 37/43] x86/xen: Pin up to VSYSCALL_ADDR when vsyscall page is out of fixmap area Hou Wenlong
2023-04-28 9:51 ` [PATCH RFC 38/43] x86/fixmap: Move vsyscall page " Hou Wenlong
2023-04-28 9:51 ` [PATCH RFC 39/43] x86/fixmap: Unify FIXADDR_TOP Hou Wenlong
2023-04-28 9:51 ` [PATCH RFC 40/43] x86/boot: Fill kernel image puds dynamically Hou Wenlong
2023-04-28 9:51 ` [PATCH RFC 41/43] x86/mm: Sort address_markers array when X86 PIE is enabled Hou Wenlong
2023-04-28 9:51 ` [PATCH RFC 42/43] x86/pie: Allow kernel image to be relocated in top 512G Hou Wenlong
2023-04-28 9:51 ` [PATCH RFC 43/43] x86/boot: Extend relocate range for PIE kernel image Hou Wenlong
2023-04-28 15:22 ` [PATCH RFC 00/43] x86/pie: Make kernel image's virtual address flexible Peter Zijlstra
2023-05-06 7:19 ` Hou Wenlong
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