From: Arvind Sankar <nivedita@alum.mit.edu>
To: Tom Lendacky <thomas.lendacky@amd.com>
Cc: Arvind Sankar <nivedita@alum.mit.edu>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
"H. Peter Anvin" <hpa@zytor.com>,
x86@kernel.org, linux-kernel@vger.kernel.org,
Kees Cook <keescook@chromium.org>,
Mauro Rossi <issor.oruam@gmail.com>, Michael Matz <matz@suse.de>
Subject: Re: [PATCH v3] x86/vmlinux: Fix vmlinux.lds.S with pre-2.23 binutils
Date: Mon, 13 Jan 2020 18:06:43 -0500 [thread overview]
Message-ID: <20200113230642.GA2000869@rani.riverdale.lan> (raw)
In-Reply-To: <3e46154d-6e5e-1c16-90fe-f2c5daa44b60@amd.com>
On Mon, Jan 13, 2020 at 03:46:04PM -0600, Tom Lendacky wrote:
> > @@ -372,7 +374,7 @@ SECTIONS
> > * explicitly reserved using memblock_reserve() or it will be discarded
> > * and treated as available memory.
> > */
> > - __end_of_kernel_reserve = .;
> > + __end_of_kernel_reserve = __bss_stop;
>
> The only thing I worry about is if someone inserts a section between
> the bss section and here and doesn't update this value.
>
> Thanks,
> Tom
Could do something like this, or maybe with just the comment?
diff --git a/arch/x86/kernel/vmlinux.lds.S b/arch/x86/kernel/vmlinux.lds.S
index bad4e22384dc..25aa1b30068e 100644
--- a/arch/x86/kernel/vmlinux.lds.S
+++ b/arch/x86/kernel/vmlinux.lds.S
@@ -373,9 +373,16 @@ SECTIONS
* automatically reserved in setup_arch(). Anything after here must be
* explicitly reserved using memblock_reserve() or it will be discarded
* and treated as available memory.
+ *
+ * Note that this is defined to use __bss_stop rather than dot for
+ * compatibility with binutils <2.23, so the definition MUST be updated
+ * if another section is added after .bss.
*/
__end_of_kernel_reserve = __bss_stop;
+ /* Used for build-time check that __end_of_kernel_reserve is correct */
+ __end_of_kernel_reserve_check = .;
+
. = ALIGN(PAGE_SIZE);
.brk : AT(ADDR(.brk) - LOAD_OFFSET) {
__brk_base = .;
@@ -451,6 +458,9 @@ INIT_PER_CPU(irq_stack_backing_store);
#endif /* CONFIG_X86_32 */
+. = ASSERT(__end_of_kernel_reserve == __end_of_kernel_reserve_check,
+ "__end_of_kernel_reserve is incorrectly defined");
+
#ifdef CONFIG_KEXEC_CORE
#include <asm/kexec.h>
next prev parent reply other threads:[~2020-01-13 23:06 UTC|newest]
Thread overview: 56+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-10 20:23 [PATCH] x86/tools/relocs: Add _etext and __end_of_kernel_reserve to S_REL Arvind Sankar
2020-01-10 20:38 ` Borislav Petkov
2020-01-10 20:50 ` Arvind Sankar
2020-01-10 21:50 ` [PATCH v2] " Arvind Sankar
2020-01-10 21:52 ` Arvind Sankar
2020-01-11 13:02 ` [PATCH] " Borislav Petkov
2020-01-11 17:20 ` Arvind Sankar
2020-01-11 17:32 ` Arvind Sankar
2020-01-13 13:43 ` Borislav Petkov
2020-01-13 16:13 ` Arvind Sankar
2020-01-13 16:38 ` Borislav Petkov
2020-01-13 17:59 ` Arvind Sankar
2020-01-13 18:08 ` Borislav Petkov
2020-01-14 4:17 ` Arvind Sankar
2020-01-14 11:25 ` Borislav Petkov
2020-01-14 16:32 ` Arvind Sankar
2020-01-14 4:08 ` Arvind Sankar
2020-01-13 19:53 ` [PATCH v3] x86/vmlinux: Fix vmlinux.lds.S with pre-2.23 binutils Arvind Sankar
2020-01-13 21:46 ` Tom Lendacky
2020-01-13 23:06 ` Arvind Sankar [this message]
2020-01-14 1:53 ` Kees Cook
2020-01-14 1:57 ` H. Peter Anvin
2020-01-14 2:20 ` Kees Cook
2020-01-14 3:58 ` Arvind Sankar
2020-01-14 5:05 ` hpa
2020-01-14 16:51 ` Borislav Petkov
2020-01-14 21:50 ` hpa
2020-01-15 0:21 ` Arvind Sankar
2020-01-15 12:24 ` Borislav Petkov
2020-03-16 16:02 ` [PATCH] Documentation/changes: Raise minimum supported binutils version to 2.23 Borislav Petkov
2020-03-16 20:54 ` Kees Cook
2020-03-23 20:44 ` Jason A. Donenfeld
2020-03-23 20:51 ` Kees Cook
2020-03-23 21:11 ` Jason A. Donenfeld
2020-03-25 17:33 ` David Laight
2020-03-24 9:02 ` Masahiro Yamada
2020-03-24 9:12 ` Masahiro Yamada
2020-03-24 15:38 ` Arvind Sankar
2020-03-24 17:31 ` Masahiro Yamada
2020-03-24 21:36 ` Arvind Sankar
2020-03-24 9:14 ` Borislav Petkov
2020-03-24 9:40 ` Masahiro Yamada
2020-03-24 12:00 ` Borislav Petkov
2020-03-24 16:22 ` Jason A. Donenfeld
2020-03-24 16:28 ` Borislav Petkov
2020-03-24 16:37 ` Linus Torvalds
2020-03-24 16:48 ` Borislav Petkov
2020-03-24 21:42 ` Arvind Sankar
2020-03-24 22:01 ` Arvind Sankar
2020-03-24 22:14 ` Linus Torvalds
2020-03-24 23:49 ` Arvind Sankar
2020-03-24 17:53 ` Kees Cook
2020-03-23 20:50 ` [PATCH] Documentation/changes: Raise minimum supported binutilsa " Nick Desaulniers
2020-01-13 23:38 ` [PATCH] x86/tools/relocs: Add _etext and __end_of_kernel_reserve to S_REL Arvind Sankar
2020-01-10 20:56 ` Kees Cook
[not found] ` <CAEQFVGa4fksPRtiLtBckSgbJY_JSHr07hoy5+5w-pAYym16YVg@mail.gmail.com>
2020-01-11 19:40 ` Fwd: " Mauro Rossi
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