From: Michael Ellerman mpe@ellerman.id.au
[ 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@ellerman.id.au Link: https://lore.kernel.org/r/20220916131422.318752-2-mpe@ellerman.id.au Stable-dep-of: 111bcb373853 ("powerpc/64s/radix: Fix RWX mapping with relocated kernel") Signed-off-by: Sasha Levin sashal@kernel.org --- arch/powerpc/include/asm/sections.h | 1 + arch/powerpc/kernel/vmlinux.lds.S | 9 +++++++-- arch/powerpc/mm/book3s32/mmu.c | 2 +- arch/powerpc/mm/book3s64/radix_pgtable.c | 4 ++-- 4 files changed, 11 insertions(+), 5 deletions(-)
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; }