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Merge branch 'for-next/scs' into for-next/core

Support for Clang's Shadow Call Stack in the kernel (Sami Tolvanen and Will Deacon) * for-next/scs: arm64: entry-ftrace.S: Update comment to indicate that x18 is live scs: Move DEFINE_SCS macro into core code scs: Remove references to asm/scs.h from core code scs: Move scs_overflow_check() out of architecture code arm64: scs: Use 'scs_sp' register alias for x18 scs: Move accounting into alloc/free functions arm64: scs: Store absolute SCS stack pointer value in thread_info efi/libstub: Disable Shadow Call Stack arm64: scs: Add shadow stacks for SDEI arm64: Implement Shadow Call Stack arm64: Disable SCS for hypervisor code arm64: vdso: Disable Shadow Call Stack arm64: efi: Restore register x18 if it was corrupted arm64: Preserve register x18 when CPU is suspended arm64: Reserve register x18 from general allocation with SCS scs: Disable when function graph tracing is enabled scs: Add support for stack usage debugging scs: Add page accounting for shadow call stack allocations scs: Add support for Clang's Shadow Call Stack (SCS)

Will Deacon committed 6 years ago

Commit 082af5e2 parents c350717 258c3d631 files · +406 −9Browse files

Showing the changes to include/linux (4 of 31 files). Show all

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4 files
  1. include/linux/compiler-clang.h +4 −0
  2. include/linux/compiler_types.h +4 −0
  3. include/linux/mmzone.h +3 −0
  4. include/linux/scs.h +72 −0
include/linux/compiler-clang.h+4−0
@@ -42,3 +42,7 @@ · 41 unmodified lines
42 * compilers, like ICC.42 * compilers, like ICC.
43 */43 */
44#define barrier() __asm__ __volatile__("" : : : "memory")44#define barrier() __asm__ __volatile__("" : : : "memory")
45
46#if __has_feature(shadow_call_stack)
47# define __noscs __attribute__((__no_sanitize__("shadow-call-stack")))
48#endif
include/linux/compiler_types.h+4−0
@@ -193,6 +193,10 @@ struct ftrace_likely_data { · 192 unmodified lines
193# define randomized_struct_fields_end193# define randomized_struct_fields_end
194#endif194#endif
195 195
196#ifndef __noscs
197# define __noscs
198#endif
199
196#ifndef asm_volatile_goto200#ifndef asm_volatile_goto
197#define asm_volatile_goto(x...) asm goto(x)201#define asm_volatile_goto(x...) asm goto(x)
198#endif202#endif
include/linux/mmzone.h+3−0
@@ -156,6 +156,9 @@ enum zone_stat_item { · 155 unmodified lines
156 NR_MLOCK, /* mlock()ed pages found and moved off LRU */156 NR_MLOCK, /* mlock()ed pages found and moved off LRU */
157 NR_PAGETABLE, /* used for pagetables */157 NR_PAGETABLE, /* used for pagetables */
158 NR_KERNEL_STACK_KB, /* measured in KiB */158 NR_KERNEL_STACK_KB, /* measured in KiB */
159#if IS_ENABLED(CONFIG_SHADOW_CALL_STACK)
160 NR_KERNEL_SCS_KB, /* measured in KiB */
161#endif
159 /* Second 128 byte cacheline */162 /* Second 128 byte cacheline */
160 NR_BOUNCE,163 NR_BOUNCE,
161#if IS_ENABLED(CONFIG_ZSMALLOC)164#if IS_ENABLED(CONFIG_ZSMALLOC)
include/linux/scs.h+72−0
@@ -0,0 +1,72 @@
1/* SPDX-License-Identifier: GPL-2.0 */
2/*
3 * Shadow Call Stack support.
4 *
5 * Copyright (C) 2019 Google LLC
6 */
7
8#ifndef _LINUX_SCS_H
9#define _LINUX_SCS_H
10
11#include <linux/gfp.h>
12#include <linux/poison.h>
13#include <linux/sched.h>
14#include <linux/sizes.h>
15
16#ifdef CONFIG_SHADOW_CALL_STACK
17
18/*
19 * In testing, 1 KiB shadow stack size (i.e. 128 stack frames on a 64-bit
20 * architecture) provided ~40% safety margin on stack usage while keeping
21 * memory allocation overhead reasonable.
22 */
23#define SCS_SIZE SZ_1K
24#define GFP_SCS (GFP_KERNEL | __GFP_ZERO)
25
26/* An illegal pointer value to mark the end of the shadow stack. */
27#define SCS_END_MAGIC (0x5f6UL + POISON_POINTER_DELTA)
28
29/* Allocate a static per-CPU shadow stack */
30#define DEFINE_SCS(name) \
31 DEFINE_PER_CPU(unsigned long [SCS_SIZE/sizeof(long)], name) \
32
33#define task_scs(tsk) (task_thread_info(tsk)->scs_base)
34#define task_scs_sp(tsk) (task_thread_info(tsk)->scs_sp)
35
36void scs_init(void);
37int scs_prepare(struct task_struct *tsk, int node);
38void scs_release(struct task_struct *tsk);
39
40static inline void scs_task_reset(struct task_struct *tsk)
41{
42 /*
43 * Reset the shadow stack to the base address in case the task
44 * is reused.
45 */
46 task_scs_sp(tsk) = task_scs(tsk);
47}
48
49static inline unsigned long *__scs_magic(void *s)
50{
51 return (unsigned long *)(s + SCS_SIZE) - 1;
52}
53
54static inline bool task_scs_end_corrupted(struct task_struct *tsk)
55{
56 unsigned long *magic = __scs_magic(task_scs(tsk));
57 unsigned long sz = task_scs_sp(tsk) - task_scs(tsk);
58
59 return sz >= SCS_SIZE - 1 || READ_ONCE_NOCHECK(*magic) != SCS_END_MAGIC;
60}
61
62#else /* CONFIG_SHADOW_CALL_STACK */
63
64static inline void scs_init(void) {}
65static inline void scs_task_reset(struct task_struct *tsk) {}
66static inline int scs_prepare(struct task_struct *tsk, int node) { return 0; }
67static inline void scs_release(struct task_struct *tsk) {}
68static inline bool task_scs_end_corrupted(struct task_struct *tsk) { return false; }
69
70#endif /* CONFIG_SHADOW_CALL_STACK */
71
72#endif /* _LINUX_SCS_H */