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Subject[PATCH v7 14/14] x86: Discard .note.gnu.property sections
Date
From: "H.J. Lu" <hjl.tools@gmail.com>

With the command-line option, -mx86-used-note=yes, the x86 assembler
in binutils 2.32 and above generates a program property note in a note
section, .note.gnu.property, to encode used x86 ISAs and features.
To exclude .note.gnu.property sections from NOTE segment in x86 kernel
linker script:

PHDRS {
text PT_LOAD FLAGS(5);
data PT_LOAD FLAGS(6);
percpu PT_LOAD FLAGS(6);
init PT_LOAD FLAGS(7);
note PT_NOTE FLAGS(0);
}
SECTIONS
{
...
.notes : AT(ADDR(.notes) - 0xffffffff80000000) { __start_notes = .; KEEP(*(.not
e.*)) __stop_notes = .; } :text :note
...
}

this patch discards .note.gnu.property sections in kernel linker script
by adding

/DISCARD/ : {
*(.note.gnu.property)
}

before .notes sections. Since .exit.text and .exit.data sections are
discarded at runtime, it undefines EXIT_TEXT and EXIT_DATA to exclude
.exit.text and .exit.data sections from default discarded sections.

Signed-off-by: H.J. Lu <hjl.tools@gmail.com>
---
arch/x86/kernel/vmlinux.lds.S | 11 ++++++++++-
1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kernel/vmlinux.lds.S b/arch/x86/kernel/vmlinux.lds.S
index 0850b5149345..d2594b482c09 100644
--- a/arch/x86/kernel/vmlinux.lds.S
+++ b/arch/x86/kernel/vmlinux.lds.S
@@ -146,6 +146,10 @@ SECTIONS
/* End of text section */
_etext = .;

+ /* .note.gnu.property sections should be discarded */
+ /DISCARD/ : {
+ *(.note.gnu.property)
+ }
NOTES :text :note

EXCEPTION_TABLE(16) :text = 0x9090
@@ -382,7 +386,12 @@ SECTIONS
STABS_DEBUG
DWARF_DEBUG

- /* Sections to be discarded */
+ /* Sections to be discarded. EXIT_TEXT and EXIT_DATA discard at runtime.
+ * not link time. */
+#undef EXIT_TEXT
+#define EXIT_TEXT
+#undef EXIT_DATA
+#define EXIT_DATA
DISCARDS
/DISCARD/ : {
*(.eh_frame)
--
2.17.1
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