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| author | Ahmad Fatoum <a.fatoum@pengutronix.de> | 2024-03-04 19:59:43 +0100 |
|---|---|---|
| committer | Sascha Hauer <s.hauer@pengutronix.de> | 2024-03-05 16:28:05 +0100 |
| commit | a7e6cd8e3efa75b5625c1df3b9ae44c76dd51c0d (patch) | |
| tree | 82eed4a92a9da46807a4f73bc8444ed835283de8 /include/linux | |
| parent | 22ae71e69d20972f1f8bb80ba9fa971293d5d3f4 (diff) | |
| download | barebox-a7e6cd8e3efa75b5625c1df3b9ae44c76dd51c0d.tar.gz barebox-a7e6cd8e3efa75b5625c1df3b9ae44c76dd51c0d.tar.xz | |
pbl: introduce CONFIG_PBL_FULLY_PIC
In the quest for making barebox PBL code W^X mappable, we have now taken
care to make the ARM64 assembly routines not emit code relocations,
so let's do the same for the C code as well.
We do this by setting pragma GCC visibility push(hidden) globally. This
option is stronger than -fvisibility=hidden and ensures we are
completely position-independent. See kernel commit e544ea57ac07
("x86/boot/compressed: Force hidden visibility for all symbol references")
for more information.
Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
Link: https://lore.barebox.org/20240304190038.3486881-59-a.fatoum@pengutronix.de
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Diffstat (limited to 'include/linux')
| -rw-r--r-- | include/linux/export.h | 2 | ||||
| -rw-r--r-- | include/linux/hidden.h | 19 |
2 files changed, 20 insertions, 1 deletions
diff --git a/include/linux/export.h b/include/linux/export.h index 8f47742bea..a136d727d1 100644 --- a/include/linux/export.h +++ b/include/linux/export.h @@ -6,7 +6,7 @@ #define THIS_MODULE 0 -#ifdef CONFIG_MODULES +#if defined(CONFIG_MODULES) && !defined(__DISABLE_EXPORTS) struct kernel_symbol { diff --git a/include/linux/hidden.h b/include/linux/hidden.h new file mode 100644 index 0000000000..49a17b6b59 --- /dev/null +++ b/include/linux/hidden.h @@ -0,0 +1,19 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * When building position independent code with GCC using the -fPIC option, + * (or even the -fPIE one on older versions), it will assume that we are + * building a dynamic object (either a shared library or an executable) that + * may have symbol references that can only be resolved at load time. For a + * variety of reasons (ELF symbol preemption, the CoW footprint of the section + * that is modified by the loader), this results in all references to symbols + * with external linkage to go via entries in the Global Offset Table (GOT), + * which carries absolute addresses which need to be fixed up when the + * executable image is loaded at an offset which is different from its link + * time offset. + * + * Fortunately, there is a way to inform the compiler that such symbol + * references will be satisfied at link time rather than at load time, by + * giving them 'hidden' visibility. + */ + +#pragma GCC visibility push(hidden) |