[PATCH v5 4/5] x86: Split .init section to satisfy UEFI CA memory mitigation

[Frediano Ziglio <freddy77@gmail.com>]

From: Frediano Ziglio <frediano.ziglio@cloud.com>

Currently .init section is both writeable and executable, split data and code
to have 2 sections satisfying W^X rule.

It is a requirement for NX_COMPAT so the PE can be loaded with W^X perms
in the pagetables.

NX_COMPAT is a requirement from shim-review,
https://github.com/rhboot/shim-review#do-you-have-the-nx-bit-set-in-your-shim-if-so-is-your-entire-boot-stack-nx-compatible-and-what-testing-have-you-done-to-ensure-such-compatibility

Signed-off-by: Frediano Ziglio <frediano.ziglio@citrix.com>
Acked-by: Marek Marczykowski-Górecki <marmarek@invisiblethingslab.com>
Acked-by: Jan Beulich <jbeulich@suse.com>
--
Change since v1:
- update comment style.

Changes since v3:
- Added Acked-by.

Changes since v4:
- Added Acked-by.
---
 xen/arch/x86/xen.lds.S | 12 ++++--------
 1 file changed, 4 insertions(+), 8 deletions(-)

diff --git a/xen/arch/x86/xen.lds.S b/xen/arch/x86/xen.lds.S
index 88553513a9..70678ab83c 100644
--- a/xen/arch/x86/xen.lds.S
+++ b/xen/arch/x86/xen.lds.S
@@ -195,11 +195,7 @@ SECTIONS
   __2M_init_start = .;         /* Start of 2M superpages, mapped RWX (boot only). */
   . = ALIGN(PAGE_SIZE);             /* Init code and data */
   __init_begin = .;
-#ifdef EFI /* EFI wants to merge all of .init.*  ELF doesn't. */
-  DECL_SECTION(.init) {
-#else
   DECL_SECTION(.init.text) {
-#endif
        _sinittext = .;
        *(.init.multiboot)
        *(.init.text)
@@ -212,12 +208,12 @@ SECTIONS
         */
        *(.altinstr_replacement)
 
-#ifdef EFI /* EFI wants to merge all of .init.*  ELF doesn't. */
-       . = ALIGN(SMP_CACHE_BYTES);
-#else
   } PHDR(text)
-  DECL_SECTION(.init.data) {
+#ifdef EFI
+  /* Align to satisfy UEFI CA memory mitigation. */
+  . = ALIGN(SECTION_ALIGN);
 #endif
+  DECL_SECTION(.init.data) {
        *(.init.bss.stack_aligned)
        *(.init.data.page_aligned)
 
-- 
2.43.0