diff options
| author | Mark Rutland <[email protected]> | 2017-07-14 12:23:09 +0100 |
|---|---|---|
| committer | Mark Rutland <[email protected]> | 2017-08-15 18:34:46 +0100 |
| commit | 48ac3c18cc62d4a23d5dc5c59f8720589d0de14b (patch) | |
| tree | cf21c9b379b4acf9a509d85f6b5edb02a2b86f80 | |
| parent | c5bc503cbeee8586395aa541d2b53c69c3dd6930 (diff) | |
fork: allow arch-override of VMAP stack alignment
In some cases, an architecture might wish its stacks to be aligned to a
boundary larger than THREAD_SIZE. For example, using an alignment of
double THREAD_SIZE can allow for stack overflows smaller than
THREAD_SIZE to be detected by checking a single bit of the stack
pointer.
This patch allows architectures to override the alignment of VMAP'd
stacks, by defining THREAD_ALIGN. Where not defined, this defaults to
THREAD_SIZE, as is the case today.
Signed-off-by: Mark Rutland <[email protected]>
Reviewed-by: Will Deacon <[email protected]>
Tested-by: Laura Abbott <[email protected]>
Cc: Andy Lutomirski <[email protected]>
Cc: Ard Biesheuvel <[email protected]>
Cc: Catalin Marinas <[email protected]>
Cc: James Morse <[email protected]>
Cc: [email protected]
| -rw-r--r-- | include/linux/thread_info.h | 4 | ||||
| -rw-r--r-- | kernel/fork.c | 3 |
2 files changed, 6 insertions, 1 deletions
diff --git a/include/linux/thread_info.h b/include/linux/thread_info.h index 250a27614328..905d769d8ddc 100644 --- a/include/linux/thread_info.h +++ b/include/linux/thread_info.h @@ -38,6 +38,10 @@ enum { #ifdef __KERNEL__ +#ifndef THREAD_ALIGN +#define THREAD_ALIGN THREAD_SIZE +#endif + #ifdef CONFIG_DEBUG_STACK_USAGE # define THREADINFO_GFP (GFP_KERNEL_ACCOUNT | __GFP_NOTRACK | \ __GFP_ZERO) diff --git a/kernel/fork.c b/kernel/fork.c index 17921b0390b4..f12882a2323b 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -88,6 +88,7 @@ #include <linux/sysctl.h> #include <linux/kcov.h> #include <linux/livepatch.h> +#include <linux/thread_info.h> #include <asm/pgtable.h> #include <asm/pgalloc.h> @@ -217,7 +218,7 @@ static unsigned long *alloc_thread_stack_node(struct task_struct *tsk, int node) return s->addr; } - stack = __vmalloc_node_range(THREAD_SIZE, THREAD_SIZE, + stack = __vmalloc_node_range(THREAD_SIZE, THREAD_ALIGN, VMALLOC_START, VMALLOC_END, THREADINFO_GFP, PAGE_KERNEL, |