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| author | Christophe Leroy <christophe.leroy@csgroup.eu> | 2020-05-19 08:49:19 +0300 |
|---|---|---|
| committer | Michael Ellerman <mpe@ellerman.id.au> | 2020-05-26 15:22:22 +0300 |
| commit | a0591b60eef965f7f5255ad4696bbba9af4b43d0 (patch) | |
| tree | 22cfa6ca4e51f9fab66d544f6e6d9df2fbe9219b /arch | |
| parent | 0c8c2c9c201b44eed6c10d7c5c8d25fe5aab87ce (diff) | |
| download | linux-a0591b60eef965f7f5255ad4696bbba9af4b43d0.tar.xz | |
powerpc/mm: Don't be too strict with _etext alignment on PPC32
Similar to PPC64, accept to map RO data as ROX as a trade off between
between security and memory usage.
Having RO data executable is not a high risk as RO data can't be
modified to forge an exploit.
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/8c4a0d89d944eed984dd941e509614031a5ace2b.1589866984.git.christophe.leroy@csgroup.eu
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/powerpc/Kconfig | 26 | ||||
| -rw-r--r-- | arch/powerpc/kernel/vmlinux.lds.S | 3 |
2 files changed, 1 insertions, 28 deletions
diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig index 1d4ef4f27dec..d147d379b1b9 100644 --- a/arch/powerpc/Kconfig +++ b/arch/powerpc/Kconfig @@ -778,32 +778,6 @@ config THREAD_SHIFT Used to define the stack size. The default is almost always what you want. Only change this if you know what you are doing. -config ETEXT_SHIFT_BOOL - bool "Set custom etext alignment" if STRICT_KERNEL_RWX && \ - (PPC_BOOK3S_32 || PPC_8xx) - depends on ADVANCED_OPTIONS - help - This option allows you to set the kernel end of text alignment. When - RAM is mapped by blocks, the alignment needs to fit the size and - number of possible blocks. The default should be OK for most configs. - - Say N here unless you know what you are doing. - -config ETEXT_SHIFT - int "_etext shift" if ETEXT_SHIFT_BOOL - range 17 28 if STRICT_KERNEL_RWX && PPC_BOOK3S_32 - range 19 23 if STRICT_KERNEL_RWX && PPC_8xx - default 17 if STRICT_KERNEL_RWX && PPC_BOOK3S_32 - default 19 if STRICT_KERNEL_RWX && PPC_8xx - default PPC_PAGE_SHIFT - help - On Book3S 32 (603+), IBATs are used to map kernel text. - Smaller is the alignment, greater is the number of necessary IBATs. - - On 8xx, large pages (512kb or 8M) are used to map kernel linear - memory. Aligning to 8M reduces TLB misses as only 8M pages are used - in that case. - config DATA_SHIFT_BOOL bool "Set custom data alignment" if STRICT_KERNEL_RWX && \ (PPC_BOOK3S_32 || PPC_8xx) diff --git a/arch/powerpc/kernel/vmlinux.lds.S b/arch/powerpc/kernel/vmlinux.lds.S index 31a0f201fb6f..54f23205c2b9 100644 --- a/arch/powerpc/kernel/vmlinux.lds.S +++ b/arch/powerpc/kernel/vmlinux.lds.S @@ -15,7 +15,6 @@ #include <asm/thread_info.h> #define STRICT_ALIGN_SIZE (1 << CONFIG_DATA_SHIFT) -#define ETEXT_ALIGN_SIZE (1 << CONFIG_ETEXT_SHIFT) ENTRY(_stext) @@ -116,7 +115,7 @@ SECTIONS } :text - . = ALIGN(ETEXT_ALIGN_SIZE); + . = ALIGN(PAGE_SIZE); _etext = .; PROVIDE32 (etext = .); |