[PATCH v2 08/29] vmlinux.lds.h: Provide EMIT_PT_NOTE to indicate export of .notes

[Kees Cook <keescook@xxxxxxxxxxxx>]

In preparation for moving NOTES into RO_DATA, provide a mechanism for
architectures that want to emit a PT_NOTE Program Header to do so.

Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
---
 arch/alpha/kernel/vmlinux.lds.S   |  3 +++
 arch/ia64/kernel/vmlinux.lds.S    |  2 ++
 arch/mips/kernel/vmlinux.lds.S    | 12 ++++++------
 arch/powerpc/kernel/vmlinux.lds.S |  1 +
 arch/s390/kernel/vmlinux.lds.S    |  2 ++
 arch/x86/kernel/vmlinux.lds.S     |  2 ++
 include/asm-generic/vmlinux.lds.h |  8 ++++++++
 7 files changed, 24 insertions(+), 6 deletions(-)

diff --git a/arch/alpha/kernel/vmlinux.lds.S b/arch/alpha/kernel/vmlinux.lds.S
index 781090cacc96..363a60ba7c31 100644
--- a/arch/alpha/kernel/vmlinux.lds.S
+++ b/arch/alpha/kernel/vmlinux.lds.S
@@ -1,4 +1,7 @@
 /* SPDX-License-Identifier: GPL-2.0 */
+
+#define EMITS_PT_NOTE
+
 #include <asm-generic/vmlinux.lds.h>
 #include <asm/thread_info.h>
 #include <asm/cache.h>
diff --git a/arch/ia64/kernel/vmlinux.lds.S b/arch/ia64/kernel/vmlinux.lds.S
index 2c4f23c390ad..7cf4958b732d 100644
--- a/arch/ia64/kernel/vmlinux.lds.S
+++ b/arch/ia64/kernel/vmlinux.lds.S
@@ -5,6 +5,8 @@
 #include <asm/pgtable.h>
 #include <asm/thread_info.h>
 
+#define EMITS_PT_NOTE
+
 #include <asm-generic/vmlinux.lds.h>
 
 OUTPUT_FORMAT("elf64-ia64-little")
diff --git a/arch/mips/kernel/vmlinux.lds.S b/arch/mips/kernel/vmlinux.lds.S
index 33ee0d18fb0a..1c95612eb800 100644
--- a/arch/mips/kernel/vmlinux.lds.S
+++ b/arch/mips/kernel/vmlinux.lds.S
@@ -10,6 +10,11 @@
  */
 #define BSS_FIRST_SECTIONS *(.bss..swapper_pg_dir)
 
+/* Cavium Octeon should not have a separate PT_NOTE Program Header. */
+#ifndef CONFIG_CAVIUM_OCTEON_SOC
+#define EMITS_PT_NOTE
+#endif
+
 #include <asm-generic/vmlinux.lds.h>
 
 #undef mips
@@ -76,12 +81,7 @@ SECTIONS
 		__stop___dbe_table = .;
 	}
 
-#ifdef CONFIG_CAVIUM_OCTEON_SOC
-#define NOTES_HEADER
-#else /* CONFIG_CAVIUM_OCTEON_SOC */
-#define NOTES_HEADER :note
-#endif /* CONFIG_CAVIUM_OCTEON_SOC */
-	NOTES :text NOTES_HEADER
+	NOTES NOTES_HEADERS
 	.dummy : { *(.dummy) } :text
 
 	_sdata = .;			/* Start of data section */
diff --git a/arch/powerpc/kernel/vmlinux.lds.S b/arch/powerpc/kernel/vmlinux.lds.S
index e184a63aa5b0..7e26e20c8324 100644
--- a/arch/powerpc/kernel/vmlinux.lds.S
+++ b/arch/powerpc/kernel/vmlinux.lds.S
@@ -6,6 +6,7 @@
 #endif
 
 #define BSS_FIRST_SECTIONS *(.bss.prominit)
+#define EMITS_PT_NOTE
 
 #include <asm/page.h>
 #include <asm-generic/vmlinux.lds.h>
diff --git a/arch/s390/kernel/vmlinux.lds.S b/arch/s390/kernel/vmlinux.lds.S
index 13294fef473e..646d939346df 100644
--- a/arch/s390/kernel/vmlinux.lds.S
+++ b/arch/s390/kernel/vmlinux.lds.S
@@ -15,6 +15,8 @@
 /* Handle ro_after_init data on our own. */
 #define RO_AFTER_INIT_DATA
 
+#define EMITS_PT_NOTE
+
 #include <asm-generic/vmlinux.lds.h>
 #include <asm/vmlinux.lds.h>
 
diff --git a/arch/x86/kernel/vmlinux.lds.S b/arch/x86/kernel/vmlinux.lds.S
index 788e78978030..2e18bf5c1aed 100644
--- a/arch/x86/kernel/vmlinux.lds.S
+++ b/arch/x86/kernel/vmlinux.lds.S
@@ -21,6 +21,8 @@
 #define LOAD_OFFSET __START_KERNEL_map
 #endif
 
+#define EMITS_PT_NOTE
+
 #include <asm-generic/vmlinux.lds.h>
 #include <asm/asm-offsets.h>
 #include <asm/thread_info.h>
diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
index dae64600ccbf..f5dd45ce73f1 100644
--- a/include/asm-generic/vmlinux.lds.h
+++ b/include/asm-generic/vmlinux.lds.h
@@ -54,6 +54,14 @@
 #define LOAD_OFFSET 0
 #endif
 
+/*
+ * Only some architectures want to have the .notes segment visible in
+ * a separate PT_NOTE ELF Program Header.
+ */
+#ifdef EMITS_PT_NOTE
+#define NOTES_HEADERS		:text :note
+#endif
+
 /* Align . to a 8 byte boundary equals to maximum function alignment. */
 #define ALIGN_FUNCTION()  . = ALIGN(8)
 
-- 
2.17.1