FEX-Emu/linux
1
0
Fork 0
mirror of https://github.com/FEX-Emu/linux.git synced 2024-12-30 05:15:03 +00:00
Code Issues Actions Packages Projects Releases Wiki Activity

powerpc: Randomise lower bits of stack address

Browse Source 
Randomise the lower bits of the stack address. More randomisation is good for
security but the scatter can also help with SMT threads that share an L1. A
quick test case shows this working:

int main()
{
	int sp;
	printf("%x\n", (unsigned long)&sp & 4095);
}

before:
80
80
80
80
80

after:
610
490
300
6b0
d80

Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
This commit is contained in:
Anton Blanchard 2009-02-22 01:50:03 +00:00 committed by Benjamin Herrenschmidt
parent 2dadb987e0
commit d839088cae
2 changed files with 10 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
arch/powerpc/include/asm/system.h
View File

@ -531,7 +531,7 @@ __cmpxchg_local(volatile void *ptr, unsigned long old, unsigned long new,
#define cmpxchg64_local(ptr, o, n) __cmpxchg64_local_generic((ptr), (o), (n))
#endif
#define arch_align_stack(x) (x)
extern unsigned long arch_align_stack(unsigned long sp);
/* Used in very early kernel initialization. */
extern unsigned long reloc_offset(void);

9
arch/powerpc/kernel/process.c
View File

@ -35,6 +35,8 @@
#include <linux/utsname.h>
#include <linux/ftrace.h>
#include <linux/kernel_stat.h>
#include <linux/personality.h>
#include <linux/random.h>
#include <asm/pgtable.h>
#include <asm/uaccess.h>
@ -1138,3 +1140,10 @@ void thread_info_cache_init(void)
}
#endif /* THREAD_SHIFT < PAGE_SHIFT */
unsigned long arch_align_stack(unsigned long sp)
{
if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
sp -= get_random_int() & ~PAGE_MASK;
return sp & ~0xf;
}