From: Arvind Sankar <nivedita@alum.mit.edu>
To: x86@kernel.org
Cc: linux-kernel@vger.kernel.org
Subject: [PATCH] x86/build: Fix vmlinux size check on 64-bit
Date: Mon, 5 Oct 2020 11:15:39 -0400 [thread overview]
Message-ID: <20201005151539.2214095-1-nivedita@alum.mit.edu> (raw)
Commit b4e0409a36f4 ("x86: check vmlinux limits, 64-bit") added a check
that the size of the 64-bit kernel is less than KERNEL_IMAGE_SIZE.
The check uses (_end - _text), but this is not enough. The initial PMD
used in startup_64() (level2_kernel_pgt) can only map upto
KERNEL_IMAGE_SIZE from __START_KERNEL_map, not from _text.
The correct check is the same as for 32-bit, since LOAD_OFFSET is
defined appropriately for the two architectures. Just check
(_end - LOAD_OFFSET) against KERNEL_IMAGE_SIZE unconditionally.
Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu>
---
arch/x86/kernel/vmlinux.lds.S | 11 ++---------
1 file changed, 2 insertions(+), 9 deletions(-)
diff --git a/arch/x86/kernel/vmlinux.lds.S b/arch/x86/kernel/vmlinux.lds.S
index bf9e0adb5b7e..b38832821b98 100644
--- a/arch/x86/kernel/vmlinux.lds.S
+++ b/arch/x86/kernel/vmlinux.lds.S
@@ -454,13 +454,12 @@ SECTIONS
ASSERT(SIZEOF(.rela.dyn) == 0, "Unexpected run-time relocations (.rela) detected!")
}
-#ifdef CONFIG_X86_32
/*
* The ASSERT() sink to . is intentional, for binutils 2.14 compatibility:
*/
. = ASSERT((_end - LOAD_OFFSET <= KERNEL_IMAGE_SIZE),
"kernel image bigger than KERNEL_IMAGE_SIZE");
-#else
+#ifdef CONFIG_X86_64
/*
* Per-cpu symbols which need to be offset from __per_cpu_load
* for the boot processor.
@@ -470,18 +469,12 @@ INIT_PER_CPU(gdt_page);
INIT_PER_CPU(fixed_percpu_data);
INIT_PER_CPU(irq_stack_backing_store);
-/*
- * Build-time check on the image size:
- */
-. = ASSERT((_end - _text <= KERNEL_IMAGE_SIZE),
- "kernel image bigger than KERNEL_IMAGE_SIZE");
-
#ifdef CONFIG_SMP
. = ASSERT((fixed_percpu_data == 0),
"fixed_percpu_data is not at start of per-cpu area");
#endif
-#endif /* CONFIG_X86_32 */
+#endif /* CONFIG_X86_64 */
#ifdef CONFIG_KEXEC_CORE
#include <asm/kexec.h>
--
2.26.2
next reply other threads:[~2020-10-05 15:15 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-05 15:15 Arvind Sankar [this message]
2020-10-27 20:08 ` [PATCH] x86/build: Fix vmlinux size check on 64-bit Borislav Petkov
2020-10-27 21:14 ` Arvind Sankar
2020-10-28 13:39 ` Borislav Petkov
2020-10-28 16:45 ` Arvind Sankar
2020-10-28 19:43 ` Borislav Petkov
2020-10-28 20:45 ` Arvind Sankar
2020-10-29 16:19 ` [PATCH v2] " Arvind Sankar
2020-10-29 21:02 ` [tip: x86/build] " tip-bot2 for Arvind Sankar
2020-10-29 20:05 ` [PATCH] " Borislav Petkov
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