diff options
| author | Christophe Leroy <christophe.leroy@csgroup.eu> | 2022-04-09 19:17:37 +0200 |
|---|---|---|
| committer | Michael Ellerman <mpe@ellerman.id.au> | 2022-05-05 22:11:58 +1000 |
| commit | 3ba4289a3e7ff4a89a78c4f74d694a344e8d9cc9 (patch) | |
| tree | 3a66e65955d97ab18ad180ff31a45e0defe4175f /arch/powerpc/mm/book3s64/hash_utils.c | |
| parent | 36e5f9ee776cb6db6ab8cb9b056076c4492b9871 (diff) | |
powerpc: Simplify and move arch_randomize_brk()
arch_randomize_brk() is only needed for hash on book3s/64, for other
platforms the one provided by the default mmap layout is good enough.
Move it to hash_utils.c and use randomize_page() like the generic one.
And properly opt out the radix case instead of making an assumption
on mmu_highuser_ssize.
Also change to a 32M range like most other architectures instead of 8M.
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/eafa4d18ec8ac7b98dd02b40181e61643707cc7c.1649523076.git.christophe.leroy@csgroup.eu
Diffstat (limited to 'arch/powerpc/mm/book3s64/hash_utils.c')
| -rw-r--r-- | arch/powerpc/mm/book3s64/hash_utils.c | 19 |
1 files changed, 19 insertions, 0 deletions
diff --git a/arch/powerpc/mm/book3s64/hash_utils.c b/arch/powerpc/mm/book3s64/hash_utils.c index 43ecad8f9564..72a3eca02449 100644 --- a/arch/powerpc/mm/book3s64/hash_utils.c +++ b/arch/powerpc/mm/book3s64/hash_utils.c @@ -37,6 +37,8 @@ #include <linux/cpu.h> #include <linux/pgtable.h> #include <linux/debugfs.h> +#include <linux/random.h> +#include <linux/elf-randomize.h> #include <asm/interrupt.h> #include <asm/processor.h> @@ -2133,3 +2135,20 @@ void __init print_system_hash_info(void) if (htab_hash_mask) pr_info("htab_hash_mask = 0x%lx\n", htab_hash_mask); } + +unsigned long arch_randomize_brk(struct mm_struct *mm) +{ + /* + * If we are using 1TB segments and we are allowed to randomise + * the heap, we can put it above 1TB so it is backed by a 1TB + * segment. Otherwise the heap will be in the bottom 1TB + * which always uses 256MB segments and this may result in a + * performance penalty. + */ + if (is_32bit_task()) + return randomize_page(mm->brk, SZ_32M); + else if (!radix_enabled() && mmu_highuser_ssize == MMU_SEGSIZE_1T) + return randomize_page(max_t(unsigned long, mm->brk, SZ_1T), SZ_1G); + else + return randomize_page(mm->brk, SZ_1G); +} |