git/linux-cryptodev-2.6
1
0
Fork 0
mirror of https://git.kernel.org/pub/scm/linux/kernel/git/herbert/cryptodev-2.6.git synced 2026-04-18 03:23:53 -04:00
Code Issues Packages Projects Releases Wiki Activity

scs: add support for dynamic shadow call stacks

Browse Source 
In order to allow arches to use code patching to conditionally emit the
shadow stack pushes and pops, rather than always taking the performance
hit even on CPUs that implement alternatives such as stack pointer
authentication on arm64, add a Kconfig symbol that can be set by the
arch to omit the SCS codegen itself, without otherwise affecting how
support code for SCS and compiler options (for register reservation, for
instance) are emitted.

Also, add a static key and some plumbing to omit the allocation of
shadow call stack for dynamic SCS configurations if SCS is disabled at
runtime.

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Sami Tolvanen <samitolvanen@google.com>
Tested-by: Sami Tolvanen <samitolvanen@google.com>
Link: https://lore.kernel.org/r/20221027155908.1940624-3-ardb@kernel.org
Signed-off-by: Will Deacon <will@kernel.org>
This commit is contained in:
Ard Biesheuvel
2022-10-27 17:59:07 +02:00
committed by Will Deacon
parent 68c76ad4a9
commit 9beccca098
4 changed files with 39 additions and 2 deletions
Download Patch File Download Diff File Expand all files Collapse all files

14
kernel/scs.c
View File

@@ -12,6 +12,10 @@
#include <linux/vmalloc.h>
#include <linux/vmstat.h>
#ifdef CONFIG_DYNAMIC_SCS
DEFINE_STATIC_KEY_FALSE(dynamic_scs_enabled);
#endif
static void __scs_account(void *s, int account)
{
struct page *scs_page = vmalloc_to_page(s);
@@ -101,14 +105,20 @@ static int scs_cleanup(unsigned int cpu)
void __init scs_init(void)
{
if (!scs_is_enabled())
return;
cpuhp_setup_state(CPUHP_BP_PREPARE_DYN, "scs:scs_cache", NULL,
scs_cleanup);
}
int scs_prepare(struct task_struct *tsk, int node)
{
void *s = scs_alloc(node);
void *s;
if (!scs_is_enabled())
return 0;
s = scs_alloc(node);
if (!s)
return -ENOMEM;
@@ -148,7 +158,7 @@ void scs_release(struct task_struct *tsk)
{
void *s = task_scs(tsk);
if (!s)
if (!scs_is_enabled() || !s)
return;
WARN(task_scs_end_corrupted(tsk),