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-rw-r--r--arch/powerpc/Kconfig44
-rw-r--r--arch/powerpc/mm/mmap.c11
2 files changed, 50 insertions, 5 deletions
diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 9ff731f50a29..276a624ec355 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -22,6 +22,48 @@ config MMU
bool
default y
+config ARCH_MMAP_RND_BITS_MAX
+ # On Book3S 64, the default virtual address space for 64-bit processes
+ # is 2^47 (128TB). As a maximum, allow randomisation to consume up to
+ # 32T of address space (2^45), which should ensure a reasonable gap
+ # between bottom-up and top-down allocations for applications that
+ # consume "normal" amounts of address space. Book3S 64 only supports 64K
+ # and 4K page sizes.
+ default 29 if PPC_BOOK3S_64 && PPC_64K_PAGES # 29 = 45 (32T) - 16 (64K)
+ default 33 if PPC_BOOK3S_64 # 33 = 45 (32T) - 12 (4K)
+ #
+ # On all other 64-bit platforms (currently only Book3E), the virtual
+ # address space is 2^46 (64TB). Allow randomisation to consume up to 16T
+ # of address space (2^44). Only 4K page sizes are supported.
+ default 32 if 64BIT # 32 = 44 (16T) - 12 (4K)
+ #
+ # For 32-bit, use the compat values, as they're the same.
+ default ARCH_MMAP_RND_COMPAT_BITS_MAX
+
+config ARCH_MMAP_RND_BITS_MIN
+ # Allow randomisation to consume up to 1GB of address space (2^30).
+ default 14 if 64BIT && PPC_64K_PAGES # 14 = 30 (1GB) - 16 (64K)
+ default 18 if 64BIT # 18 = 30 (1GB) - 12 (4K)
+ #
+ # For 32-bit, use the compat values, as they're the same.
+ default ARCH_MMAP_RND_COMPAT_BITS_MIN
+
+config ARCH_MMAP_RND_COMPAT_BITS_MAX
+ # Total virtual address space for 32-bit processes is 2^31 (2GB).
+ # Allow randomisation to consume up to 512MB of address space (2^29).
+ default 11 if PPC_256K_PAGES # 11 = 29 (512MB) - 18 (256K)
+ default 13 if PPC_64K_PAGES # 13 = 29 (512MB) - 16 (64K)
+ default 15 if PPC_16K_PAGES # 15 = 29 (512MB) - 14 (16K)
+ default 17 # 17 = 29 (512MB) - 12 (4K)
+
+config ARCH_MMAP_RND_COMPAT_BITS_MIN
+ # Total virtual address space for 32-bit processes is 2^31 (2GB).
+ # Allow randomisation to consume up to 8MB of address space (2^23).
+ default 5 if PPC_256K_PAGES # 5 = 23 (8MB) - 18 (256K)
+ default 7 if PPC_64K_PAGES # 7 = 23 (8MB) - 16 (64K)
+ default 9 if PPC_16K_PAGES # 9 = 23 (8MB) - 14 (16K)
+ default 11 # 11 = 23 (8MB) - 12 (4K)
+
config HAVE_SETUP_PER_CPU_AREA
def_bool PPC64
@@ -120,6 +162,8 @@ config PPC
select HAVE_ARCH_HARDENED_USERCOPY
select HAVE_ARCH_JUMP_LABEL
select HAVE_ARCH_KGDB
+ select HAVE_ARCH_MMAP_RND_BITS
+ select HAVE_ARCH_MMAP_RND_COMPAT_BITS if COMPAT
select HAVE_ARCH_SECCOMP_FILTER
select HAVE_ARCH_TRACEHOOK
select HAVE_CBPF_JIT if !PPC64
diff --git a/arch/powerpc/mm/mmap.c b/arch/powerpc/mm/mmap.c
index 82fc5762f971..005aa8a44915 100644
--- a/arch/powerpc/mm/mmap.c
+++ b/arch/powerpc/mm/mmap.c
@@ -59,13 +59,14 @@ static inline int mmap_is_legacy(void)
unsigned long arch_mmap_rnd(void)
{
- unsigned long rnd;
+ unsigned long shift, rnd;
- /* 8MB for 32bit, 1GB for 64bit */
+ shift = mmap_rnd_bits;
+#ifdef CONFIG_COMPAT
if (is_32bit_task())
- rnd = get_random_long() % (1<<(23-PAGE_SHIFT));
- else
- rnd = get_random_long() % (1UL<<(30-PAGE_SHIFT));
+ shift = mmap_rnd_compat_bits;
+#endif
+ rnd = get_random_long() % (1 << shift);
return rnd << PAGE_SHIFT;
}