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Subject[tip: x86/boot] x86/vmlinux: Drop unneeded linker script discard of .eh_frame
The following commit has been merged into the x86/boot branch of tip:

Commit-ID: 6f8f0dc980028e98ae339876a8403edae4d20e39
Gitweb: https://git.kernel.org/tip/6f8f0dc980028e98ae339876a8403edae4d20e39
Author: Arvind Sankar <nivedita@alum.mit.edu>
AuthorDate: Mon, 24 Feb 2020 18:21:29 -05:00
Committer: Borislav Petkov <bp@suse.de>
CommitterDate: Tue, 25 Feb 2020 14:51:29 +01:00

x86/vmlinux: Drop unneeded linker script discard of .eh_frame

Now that .eh_frame sections for the files in setup.elf and realmode.elf
are not generated anymore, the linker scripts don't need the special
output section name /DISCARD/ any more.

Remove the one in the main kernel linker script as well, since there are
no .eh_frame sections already, and fix up a comment referencing .eh_frame.

Update the comment in asm/dwarf2.h referring to .eh_frame so it continues
to make sense, as well as being more specific.

[ bp: Touch up commit message. ]

Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Nathan Chancellor <natechancellor@gmail.com>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Tested-by: Nathan Chancellor <natechancellor@gmail.com>
Link: https://lkml.kernel.org/r/20200224232129.597160-3-nivedita@alum.mit.edu
---
arch/x86/boot/compressed/vmlinux.lds.S | 5 -----
arch/x86/boot/setup.ld | 1 -
arch/x86/include/asm/dwarf2.h | 4 ++--
arch/x86/kernel/vmlinux.lds.S | 7 ++-----
arch/x86/realmode/rm/realmode.lds.S | 1 -
5 files changed, 4 insertions(+), 14 deletions(-)

diff --git a/arch/x86/boot/compressed/vmlinux.lds.S b/arch/x86/boot/compressed/vmlinux.lds.S
index 469dcf8..508cfa6 100644
--- a/arch/x86/boot/compressed/vmlinux.lds.S
+++ b/arch/x86/boot/compressed/vmlinux.lds.S
@@ -73,9 +73,4 @@ SECTIONS
#endif
. = ALIGN(PAGE_SIZE); /* keep ZO size page aligned */
_end = .;
-
- /* Discard .eh_frame to save some space */
- /DISCARD/ : {
- *(.eh_frame)
- }
}
diff --git a/arch/x86/boot/setup.ld b/arch/x86/boot/setup.ld
index 3da1c37..24c9552 100644
--- a/arch/x86/boot/setup.ld
+++ b/arch/x86/boot/setup.ld
@@ -52,7 +52,6 @@ SECTIONS
_end = .;

/DISCARD/ : {
- *(.eh_frame)
*(.note*)
}

diff --git a/arch/x86/include/asm/dwarf2.h b/arch/x86/include/asm/dwarf2.h
index ae391f6..f71a0cc 100644
--- a/arch/x86/include/asm/dwarf2.h
+++ b/arch/x86/include/asm/dwarf2.h
@@ -42,8 +42,8 @@
* Emit CFI data in .debug_frame sections, not .eh_frame sections.
* The latter we currently just discard since we don't do DWARF
* unwinding at runtime. So only the offline DWARF information is
- * useful to anyone. Note we should not use this directive if
- * vmlinux.lds.S gets changed so it doesn't discard .eh_frame.
+ * useful to anyone. Note we should not use this directive if we
+ * ever decide to enable DWARF unwinding at runtime.
*/
.cfi_sections .debug_frame
#else
diff --git a/arch/x86/kernel/vmlinux.lds.S b/arch/x86/kernel/vmlinux.lds.S
index e3296aa..5cab3a2 100644
--- a/arch/x86/kernel/vmlinux.lds.S
+++ b/arch/x86/kernel/vmlinux.lds.S
@@ -313,8 +313,8 @@ SECTIONS

. = ALIGN(8);
/*
- * .exit.text is discard at runtime, not link time, to deal with
- * references from .altinstructions and .eh_frame
+ * .exit.text is discarded at runtime, not link time, to deal with
+ * references from .altinstructions
*/
.exit.text : AT(ADDR(.exit.text) - LOAD_OFFSET) {
EXIT_TEXT
@@ -412,9 +412,6 @@ SECTIONS
DWARF_DEBUG

DISCARDS
- /DISCARD/ : {
- *(.eh_frame)
- }
}


diff --git a/arch/x86/realmode/rm/realmode.lds.S b/arch/x86/realmode/rm/realmode.lds.S
index 64d135d..63aa518 100644
--- a/arch/x86/realmode/rm/realmode.lds.S
+++ b/arch/x86/realmode/rm/realmode.lds.S
@@ -71,7 +71,6 @@ SECTIONS
/DISCARD/ : {
*(.note*)
*(.debug*)
- *(.eh_frame*)
}

#include "pasyms.h"
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