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Subject[RFC 12/17] arm64: move ptrauth keys to thread_info
Date
From: Mark Rutland <mark.rutland@arm.com>

To use pointer authentication in the kernel, we'll need to switch keys
in the entry assembly. This patch moves the pointer auth keys into
thread_info to make this possible.

There should be no functional change as a result of this patch.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Kristina Martsenko <kristina.martsenko@arm.com>
---
arch/arm64/include/asm/mmu.h | 5 -----
arch/arm64/include/asm/mmu_context.h | 13 -------------
arch/arm64/include/asm/pointer_auth.h | 13 +++++++------
arch/arm64/include/asm/thread_info.h | 4 ++++
arch/arm64/kernel/process.c | 4 ++++
5 files changed, 15 insertions(+), 24 deletions(-)

diff --git a/arch/arm64/include/asm/mmu.h b/arch/arm64/include/asm/mmu.h
index f6480ea7b0d5..dd320df0d026 100644
--- a/arch/arm64/include/asm/mmu.h
+++ b/arch/arm64/include/asm/mmu.h
@@ -25,15 +25,10 @@

#ifndef __ASSEMBLY__

-#include <asm/pointer_auth.h>
-
typedef struct {
atomic64_t id;
void *vdso;
unsigned long flags;
-#ifdef CONFIG_ARM64_PTR_AUTH
- struct ptrauth_keys ptrauth_keys;
-#endif
} mm_context_t;

/*
diff --git a/arch/arm64/include/asm/mmu_context.h b/arch/arm64/include/asm/mmu_context.h
index 983f80925566..387e810063c7 100644
--- a/arch/arm64/include/asm/mmu_context.h
+++ b/arch/arm64/include/asm/mmu_context.h
@@ -215,8 +215,6 @@ static inline void __switch_mm(struct mm_struct *next)
return;
}

- mm_ctx_ptrauth_switch(&next->context);
-
check_and_switch_context(next, cpu);
}

@@ -242,17 +240,6 @@ switch_mm(struct mm_struct *prev, struct mm_struct *next,
void verify_cpu_asid_bits(void);
void post_ttbr_update_workaround(void);

-static inline void arch_bprm_mm_init(struct mm_struct *mm,
- struct vm_area_struct *vma)
-{
- mm_ctx_ptrauth_init(&mm->context);
-}
-#define arch_bprm_mm_init arch_bprm_mm_init
-
-/*
- * We need to override arch_bprm_mm_init before including the generic hooks,
- * which are otherwise sufficient for us.
- */
#include <asm-generic/mm_hooks.h>

#endif /* !__ASSEMBLY__ */
diff --git a/arch/arm64/include/asm/pointer_auth.h b/arch/arm64/include/asm/pointer_auth.h
index f5a4b075be65..cedb03bd175b 100644
--- a/arch/arm64/include/asm/pointer_auth.h
+++ b/arch/arm64/include/asm/pointer_auth.h
@@ -63,16 +63,17 @@ static inline unsigned long ptrauth_strip_insn_pac(unsigned long ptr)
return ptr & ~ptrauth_pac_mask();
}

-#define mm_ctx_ptrauth_init(ctx) \
- ptrauth_keys_init(&(ctx)->ptrauth_keys)
+#define ptrauth_task_init_user(tsk) \
+ ptrauth_keys_init(&(tsk)->thread_info.keys_user); \
+ ptrauth_keys_switch(&(tsk)->thread_info.keys_user)

-#define mm_ctx_ptrauth_switch(ctx) \
- ptrauth_keys_switch(&(ctx)->ptrauth_keys)
+#define ptrauth_task_switch(tsk) \
+ ptrauth_keys_switch(&(tsk)->thread_info.keys_user)

#else /* CONFIG_ARM64_PTR_AUTH */
#define ptrauth_strip_insn_pac(lr) (lr)
-#define mm_ctx_ptrauth_init(ctx)
-#define mm_ctx_ptrauth_switch(ctx)
+#define ptrauth_task_init_user(tsk)
+#define ptrauth_task_switch(tsk)
#endif /* CONFIG_ARM64_PTR_AUTH */

#endif /* __ASM_POINTER_AUTH_H */
diff --git a/arch/arm64/include/asm/thread_info.h b/arch/arm64/include/asm/thread_info.h
index cb2c10a8f0a8..ea9272fb52d4 100644
--- a/arch/arm64/include/asm/thread_info.h
+++ b/arch/arm64/include/asm/thread_info.h
@@ -28,6 +28,7 @@
struct task_struct;

#include <asm/memory.h>
+#include <asm/pointer_auth.h>
#include <asm/stack_pointer.h>
#include <asm/types.h>

@@ -43,6 +44,9 @@ struct thread_info {
u64 ttbr0; /* saved TTBR0_EL1 */
#endif
int preempt_count; /* 0 => preemptable, <0 => bug */
+#ifdef CONFIG_ARM64_PTR_AUTH
+ struct ptrauth_keys keys_user;
+#endif
};

#define thread_saved_pc(tsk) \
diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c
index 7f1628effe6d..fae52be66c92 100644
--- a/arch/arm64/kernel/process.c
+++ b/arch/arm64/kernel/process.c
@@ -57,6 +57,7 @@
#include <asm/fpsimd.h>
#include <asm/mmu_context.h>
#include <asm/processor.h>
+#include <asm/pointer_auth.h>
#include <asm/stacktrace.h>

#ifdef CONFIG_STACKPROTECTOR
@@ -425,6 +426,7 @@ __notrace_funcgraph struct task_struct *__switch_to(struct task_struct *prev,
contextidr_thread_switch(next);
entry_task_switch(next);
uao_thread_switch(next);
+ ptrauth_task_switch(next);

/*
* Complete any pending TLB or cache maintenance on this CPU in case
@@ -492,6 +494,8 @@ unsigned long arch_randomize_brk(struct mm_struct *mm)
void arch_setup_new_exec(void)
{
current->mm->context.flags = is_compat_task() ? MMCF_AARCH32 : 0;
+
+ ptrauth_task_init_user(current);
}

#ifdef CONFIG_GCC_PLUGIN_STACKLEAK
--
2.11.0
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