BACKPORT: arm64: ensure _stext and _etext are page-aligned

Currently we have separate ALIGN_DEBUG_RO{,_MIN} directives to align
_etext and __init_begin. While we ensure that __init_begin is
page-aligned, we do not provide the same guarantee for _etext. This is
not problematic currently as the alignment of __init_begin is sufficient
to prevent issues when we modify permissions.

Subsequent patches will assume page alignment of segments of the kernel
we wish to map with different permissions. To ensure this, move _etext
after the ALIGN_DEBUG_RO_MIN for the init section. This renders the
prior ALIGN_DEBUG_RO irrelevant, and hence it is removed. Likewise,
upgrade to ALIGN_DEBUG_RO_MIN(PAGE_SIZE) for _stext.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Tested-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Tested-by: Jeremy Linton <jeremy.linton@arm.com>
Cc: Laura Abbott <labbott@fedoraproject.org>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Bug: 30369029
Patchset: rework-pagetable

(cherry picked from commit fca082bfb543ccaaff864fc0892379ccaa1711cd)
Signed-off-by: Jeff Vander Stoep <jeffv@google.com>
Change-Id: If1a829aa5c363f2c76eb1a18209c3c00ee3ffd0a

diff --git a/arch/arm64/kernel/vmlinux.lds.S b/arch/arm64/kernel/vmlinux.lds.S
index 1a056bb26633aeed63b19825e93b5b9bbef5a8e7..763e5aab57529011795d24c9ab82f8b765376249 100644 (file)
--- a/arch/arm64/kernel/vmlinux.lds.S
+++ b/arch/arm64/kernel/vmlinux.lds.S
@@ -95,7 +95,7 @@ SECTIONS
                _text = .;
                HEAD_TEXT
        }
-       ALIGN_DEBUG_RO
+       ALIGN_DEBUG_RO_MIN(PAGE_SIZE)
        .text : {                       /* Real text segment            */
                _stext = .;             /* Text and read-only data      */
                        __exception_text_start = .;
@@ -118,9 +118,9 @@ SECTIONS
        RO_DATA(PAGE_SIZE)
        EXCEPTION_TABLE(8)
        NOTES
-       ALIGN_DEBUG_RO
 
        ALIGN_DEBUG_RO_MIN(PAGE_SIZE)
+       _etext = .;                     /* End of text and rodata section */
        __init_begin = .;
 
        INIT_TEXT_SECTION(8)