From: Kristen Carlson Accardi <kristen@linux.intel.com>
To: keescook@chromium.org, tglx@linutronix.de, mingo@redhat.com,
bp@alien8.de, x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
Arnd Bergmann <arnd@arndb.de>
Cc: arjan@linux.intel.com, linux-kernel@vger.kernel.org,
kernel-hardening@lists.openwall.com, rick.p.edgecombe@intel.com,
Kristen Carlson Accardi <kristen@linux.intel.com>,
Tony Luck <tony.luck@intel.com>,
linux-arch@vger.kernel.org
Subject: [PATCH v4 05/10] x86: Make sure _etext includes function sections
Date: Fri, 17 Jul 2020 10:00:02 -0700 [thread overview]
Message-ID: <20200717170008.5949-6-kristen@linux.intel.com> (raw)
In-Reply-To: <20200717170008.5949-1-kristen@linux.intel.com>
When using -ffunction-sections to place each function in
it's own text section so it can be randomized at load time, the
linker considers these .text.* sections "orphaned sections", and
will place them after the first similar section (.text). In order
to accurately represent the end of the text section and the
orphaned sections, _etext must be moved so that it is after both
.text and .text.* The text size must also be calculated to
include .text AND .text.*
Signed-off-by: Kristen Carlson Accardi <kristen@linux.intel.com>
Reviewed-by: Tony Luck <tony.luck@intel.com>
Tested-by: Tony Luck <tony.luck@intel.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
---
arch/x86/kernel/vmlinux.lds.S | 17 +++++++++++++++--
include/asm-generic/vmlinux.lds.h | 2 +-
2 files changed, 16 insertions(+), 3 deletions(-)
diff --git a/arch/x86/kernel/vmlinux.lds.S b/arch/x86/kernel/vmlinux.lds.S
index 3bfc8dd8a43d..e8da7eeb4d8d 100644
--- a/arch/x86/kernel/vmlinux.lds.S
+++ b/arch/x86/kernel/vmlinux.lds.S
@@ -146,9 +146,22 @@ SECTIONS
#endif
} :text =0xcccc
- /* End of text section, which should occupy whole number of pages */
- _etext = .;
+ /*
+ * -ffunction-sections creates .text.* sections, which are considered
+ * "orphan sections" and added after the first similar section (.text).
+ * Placing this ALIGN statement before _etext causes the address of
+ * _etext to be below that of all the .text.* orphaned sections
+ */
. = ALIGN(PAGE_SIZE);
+ _etext = .;
+
+ /*
+ * the size of the .text section is used to calculate the address
+ * range for orc lookups. If we just use SIZEOF(.text), we will
+ * miss all the .text.* sections. Calculate the size using _etext
+ * and _stext and save the value for later.
+ */
+ text_size = _etext - _stext;
X86_ALIGN_RODATA_BEGIN
RO_DATA(PAGE_SIZE)
diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
index a5552cf28d5d..34eab6513fdc 100644
--- a/include/asm-generic/vmlinux.lds.h
+++ b/include/asm-generic/vmlinux.lds.h
@@ -835,7 +835,7 @@
. = ALIGN(4); \
.orc_lookup : AT(ADDR(.orc_lookup) - LOAD_OFFSET) { \
orc_lookup = .; \
- . += (((SIZEOF(.text) + LOOKUP_BLOCK_SIZE - 1) / \
+ . += (((text_size + LOOKUP_BLOCK_SIZE - 1) / \
LOOKUP_BLOCK_SIZE) + 1) * 4; \
orc_lookup_end = .; \
}
--
2.20.1
next prev parent reply other threads:[~2020-07-17 17:01 UTC|newest]
Thread overview: 46+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-17 16:59 [PATCH v4 00/10] Function Granular KASLR Kristen Carlson Accardi
2020-07-17 16:59 ` [PATCH v4 01/10] objtool: Do not assume order of parent/child functions Kristen Carlson Accardi
2020-07-17 16:59 ` [PATCH v4 02/10] x86: tools/relocs: Support >64K section headers Kristen Carlson Accardi
2020-07-17 17:00 ` [PATCH v4 03/10] x86/boot: Allow a "silent" kaslr random byte fetch Kristen Carlson Accardi
2020-07-17 17:00 ` [PATCH v4 04/10] x86: Makefile: Add build and config option for CONFIG_FG_KASLR Kristen Carlson Accardi
2020-07-17 17:00 ` Kristen Carlson Accardi [this message]
2020-07-17 17:00 ` [PATCH v4 06/10] x86/tools: Add relative relocs for randomized functions Kristen Carlson Accardi
2020-07-17 17:00 ` [PATCH v4 07/10] x86/boot/compressed: Avoid duplicate malloc() implementations Kristen Carlson Accardi
2020-07-17 17:00 ` [PATCH v4 08/10] x86: Add support for function granular KASLR Kristen Carlson Accardi
2020-07-17 17:00 ` [PATCH v4 09/10] kallsyms: Hide layout Kristen Carlson Accardi
2020-07-20 1:25 ` Kees Cook
2020-07-20 16:59 ` Kristen Carlson Accardi
2020-07-17 17:00 ` [PATCH v4 10/10] module: Reorder functions Kristen Carlson Accardi
2020-07-28 17:29 ` Jessica Yu
2020-07-22 9:27 ` [PATCH v4 00/10] Function Granular KASLR Miroslav Benes
2020-07-22 14:39 ` Kees Cook
2020-07-22 14:51 ` Joe Lawrence
2020-07-22 14:56 ` Joe Lawrence
2020-07-22 18:24 ` Kristen Carlson Accardi
2020-07-22 16:07 ` Josh Poimboeuf
2020-07-22 19:42 ` Kees Cook
2020-07-22 19:56 ` Kristen Carlson Accardi
2020-07-22 21:33 ` Josh Poimboeuf
2020-08-21 23:02 ` Kristen Carlson Accardi
2020-08-25 16:16 ` Joe Lawrence
2020-08-28 10:21 ` Miroslav Benes
2020-08-28 19:24 ` Josh Poimboeuf
2021-01-23 22:59 ` Fangrui Song
2021-01-25 17:21 ` Josh Poimboeuf
2020-08-03 11:39 ` Evgenii Shatokhin
2020-08-03 17:45 ` Kees Cook
2020-08-03 18:17 ` Joe Lawrence
2020-08-03 19:38 ` Frank Ch. Eigler
2020-08-03 20:11 ` Kees Cook
2020-08-03 21:12 ` Frank Ch. Eigler
2020-08-03 21:41 ` Kees Cook
2020-08-04 0:48 ` Frank Ch. Eigler
2020-08-04 17:04 ` Jessica Yu
2020-08-04 18:23 ` Joe Lawrence
2020-08-07 16:38 ` Kristen Carlson Accardi
2020-08-07 17:20 ` Kees Cook
2020-08-10 16:10 ` Kristen Carlson Accardi
2020-08-12 17:18 ` Kristen Carlson Accardi
2020-08-06 15:32 ` Ingo Molnar
2020-08-06 19:24 ` Kristen Carlson Accardi
2020-08-06 19:27 ` Kees Cook
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