Patch "powerpc/vmlinux.lds: Add an explicit symbol for the SRWX boundary" has been added to the 5.15-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    powerpc/vmlinux.lds: Add an explicit symbol for the SRWX boundary

to the 5.15-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     powerpc-vmlinux.lds-add-an-explicit-symbol-for-the-s.patch
and it can be found in the queue-5.15 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit f7674516e7c87e7435f4f4a4f9178c8bbb84f0d4
Author: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Date:   Fri Sep 16 14:41:24 2022 +1000

    powerpc/vmlinux.lds: Add an explicit symbol for the SRWX boundary
    
    [ Upstream commit b150a4d12b919baf956b807aa305cf78df03d0fe ]
    
    Currently __init_begin is used as the boundary for strict RWX between
    executable/read-only text and data, and non-executable (after boot) code
    and data.
    
    But that's a little subtle, so add an explicit symbol to document that
    the SRWX boundary lies there, and add a comment making it clear that
    __init_begin must also begin there.
    
    Signed-off-by: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
    Link: https://lore.kernel.org/r/20220916131422.318752-2-mpe@xxxxxxxxxxxxxx
    Stable-dep-of: 111bcb373853 ("powerpc/64s/radix: Fix RWX mapping with relocated kernel")
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/arch/powerpc/include/asm/sections.h b/arch/powerpc/include/asm/sections.h
index 79cb7a25a5fb6..e92d39c0cd1d9 100644
--- a/arch/powerpc/include/asm/sections.h
+++ b/arch/powerpc/include/asm/sections.h
@@ -9,6 +9,7 @@
 #include <asm-generic/sections.h>
 
 extern char __head_end[];
+extern char __srwx_boundary[];
 
 #ifdef __powerpc64__
 
diff --git a/arch/powerpc/kernel/vmlinux.lds.S b/arch/powerpc/kernel/vmlinux.lds.S
index bcbe41c6998ca..a664d0c4344a9 100644
--- a/arch/powerpc/kernel/vmlinux.lds.S
+++ b/arch/powerpc/kernel/vmlinux.lds.S
@@ -208,11 +208,16 @@ SECTIONS
 	}
 #endif
 
+	/*
+	 * Various code relies on __init_begin being at the strict RWX boundary.
+	 */
+	. = ALIGN(STRICT_ALIGN_SIZE);
+	__srwx_boundary = .;
+	__init_begin = .;
+
 /*
  * Init sections discarded at runtime
  */
-	. = ALIGN(STRICT_ALIGN_SIZE);
-	__init_begin = .;
 	.init.text : AT(ADDR(.init.text) - LOAD_OFFSET) {
 		_sinittext = .;
 		INIT_TEXT
diff --git a/arch/powerpc/mm/book3s32/mmu.c b/arch/powerpc/mm/book3s32/mmu.c
index bfca0afe91126..692c336e4f55b 100644
--- a/arch/powerpc/mm/book3s32/mmu.c
+++ b/arch/powerpc/mm/book3s32/mmu.c
@@ -159,7 +159,7 @@ static unsigned long __init __mmu_mapin_ram(unsigned long base, unsigned long to
 unsigned long __init mmu_mapin_ram(unsigned long base, unsigned long top)
 {
 	unsigned long done;
-	unsigned long border = (unsigned long)__init_begin - PAGE_OFFSET;
+	unsigned long border = (unsigned long)__srwx_boundary - PAGE_OFFSET;
 	unsigned long size;
 
 	size = roundup_pow_of_two((unsigned long)_einittext - PAGE_OFFSET);
diff --git a/arch/powerpc/mm/book3s64/radix_pgtable.c b/arch/powerpc/mm/book3s64/radix_pgtable.c
index a339cb5de5dd1..52e27fd995da7 100644
--- a/arch/powerpc/mm/book3s64/radix_pgtable.c
+++ b/arch/powerpc/mm/book3s64/radix_pgtable.c
@@ -260,8 +260,8 @@ print_mapping(unsigned long start, unsigned long end, unsigned long size, bool e
 static unsigned long next_boundary(unsigned long addr, unsigned long end)
 {
 #ifdef CONFIG_STRICT_KERNEL_RWX
-	if (addr < __pa_symbol(__init_begin))
-		return __pa_symbol(__init_begin);
+	if (addr < __pa_symbol(__srwx_boundary))
+		return __pa_symbol(__srwx_boundary);
 #endif
 	return end;
 }