Commit 48a8ab4e authored by Aneesh Kumar K.V's avatar Aneesh Kumar K.V Committed by Michael Ellerman
Browse files

powerpc/book3s64/pkeys: Don't update SPRN_AMR when in kernel mode. 



Now that kernel correctly store/restore userspace AMR/IAMR values, avoid
manipulating AMR and IAMR from the kernel on behalf of userspace.

Signed-off-by: default avatarAneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Reviewed-by: default avatarSandipan Das <sandipan@linux.ibm.com>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20201127044424.40686-15-aneesh.kumar@linux.ibm.com
parent edc541ec

arch/powerpc/include/asm/book3s/64/kup.h

+21 −0
Original line number Diff line number Diff line
@@ -177,6 +177,27 @@ DECLARE_STATIC_KEY_FALSE(uaccess_flush_key); 
#include <asm/mmu.h>

#include <asm/ptrace.h>



/*

 * For kernel thread that doesn't have thread.regs return

 * default AMR/IAMR values.

 */

static inline u64 current_thread_amr(void)

{

	if (current->thread.regs)

		return current->thread.regs->amr;

	return AMR_KUAP_BLOCKED;

}



static inline u64 current_thread_iamr(void)

{

	if (current->thread.regs)

		return current->thread.regs->iamr;

	return AMR_KUEP_BLOCKED;

}

#endif /* CONFIG_PPC_PKEY */



#ifdef CONFIG_PPC_KUAP



static inline void kuap_user_restore(struct pt_regs *regs)

{

	if (!mmu_has_feature(MMU_FTR_PKEY))

arch/powerpc/include/asm/processor.h

+0 −4
Original line number Diff line number Diff line
@@ -226,10 +226,6 @@ struct thread_struct { 
	struct thread_vr_state ckvr_state; /* Checkpointed VR state */

	unsigned long	ckvrsave; /* Checkpointed VRSAVE */

#endif /* CONFIG_PPC_TRANSACTIONAL_MEM */

#ifdef CONFIG_PPC_MEM_KEYS

	unsigned long	amr;

	unsigned long	iamr;

#endif

#ifdef CONFIG_KVM_BOOK3S_32_HANDLER

	void*		kvm_shadow_vcpu; /* KVM internal data */

#endif /* CONFIG_KVM_BOOK3S_32_HANDLER */

arch/powerpc/kernel/process.c

+0 −4
Original line number Diff line number Diff line
@@ -589,7 +589,6 @@ static void save_all(struct task_struct *tsk) 
		__giveup_spe(tsk);



	msr_check_and_clear(msr_all_available);

	thread_pkey_regs_save(&tsk->thread);

}



void flush_all_to_thread(struct task_struct *tsk)
@@ -1160,8 +1159,6 @@ static inline void save_sprs(struct thread_struct *t) 
		t->tar = mfspr(SPRN_TAR);

	}

#endif



	thread_pkey_regs_save(t);

}



static inline void restore_sprs(struct thread_struct *old_thread,
@@ -1202,7 +1199,6 @@ static inline void restore_sprs(struct thread_struct *old_thread, 
		mtspr(SPRN_TIDR, new_thread->tidr);

#endif



	thread_pkey_regs_restore(new_thread, old_thread);

}



struct task_struct *__switch_to(struct task_struct *prev,

arch/powerpc/kernel/traps.c

+0 −6
Original line number Diff line number Diff line
@@ -347,12 +347,6 @@ static bool exception_common(int signr, struct pt_regs *regs, int code, 


	current->thread.trap_nr = code;



	/*

	 * Save all the pkey registers AMR/IAMR/UAMOR. Eg: Core dumps need

	 * to capture the content, if the task gets killed.

	 */

	thread_pkey_regs_save(&current->thread);



	return true;

}

arch/powerpc/mm/book3s64/pkeys.c

+10 −47
Original line number Diff line number Diff line
@@ -281,30 +281,17 @@ void __init setup_kuap(bool disabled) 
}

#endif



static inline u64 read_amr(void)

static inline void update_current_thread_amr(u64 value)

{

	return mfspr(SPRN_AMR);

	current->thread.regs->amr = value;

}



static inline void write_amr(u64 value)

{

	mtspr(SPRN_AMR, value);

}



static inline u64 read_iamr(void)

{

	if (!likely(pkey_execute_disable_supported))

		return 0x0UL;



	return mfspr(SPRN_IAMR);

}



static inline void write_iamr(u64 value)

static inline void update_current_thread_iamr(u64 value)

{

	if (!likely(pkey_execute_disable_supported))

		return;



	mtspr(SPRN_IAMR, value);

	current->thread.regs->iamr = value;

}



#ifdef CONFIG_PPC_MEM_KEYS
@@ -319,17 +306,17 @@ void pkey_mm_init(struct mm_struct *mm) 
static inline void init_amr(int pkey, u8 init_bits)

{

	u64 new_amr_bits = (((u64)init_bits & 0x3UL) << pkeyshift(pkey));

	u64 old_amr = read_amr() & ~((u64)(0x3ul) << pkeyshift(pkey));

	u64 old_amr = current_thread_amr() & ~((u64)(0x3ul) << pkeyshift(pkey));



	write_amr(old_amr | new_amr_bits);

	update_current_thread_amr(old_amr | new_amr_bits);

}



static inline void init_iamr(int pkey, u8 init_bits)

{

	u64 new_iamr_bits = (((u64)init_bits & 0x1UL) << pkeyshift(pkey));

	u64 old_iamr = read_iamr() & ~((u64)(0x1ul) << pkeyshift(pkey));

	u64 old_iamr = current_thread_iamr() & ~((u64)(0x1ul) << pkeyshift(pkey));



	write_iamr(old_iamr | new_iamr_bits);

	update_current_thread_iamr(old_iamr | new_iamr_bits);

}



/*
@@ -372,30 +359,6 @@ int __arch_set_user_pkey_access(struct task_struct *tsk, int pkey, 
	return 0;

}



void thread_pkey_regs_save(struct thread_struct *thread)

{

	if (!mmu_has_feature(MMU_FTR_PKEY))

		return;



	/*

	 * TODO: Skip saving registers if @thread hasn't used any keys yet.

	 */

	thread->amr = read_amr();

	thread->iamr = read_iamr();

}



void thread_pkey_regs_restore(struct thread_struct *new_thread,

			      struct thread_struct *old_thread)

{

	if (!mmu_has_feature(MMU_FTR_PKEY))

		return;



	if (old_thread->amr != new_thread->amr)

		write_amr(new_thread->amr);

	if (old_thread->iamr != new_thread->iamr)

		write_iamr(new_thread->iamr);

}



int execute_only_pkey(struct mm_struct *mm)

{

	return mm->context.execute_only_pkey;
@@ -444,9 +407,9 @@ static bool pkey_access_permitted(int pkey, bool write, bool execute) 


	pkey_shift = pkeyshift(pkey);

	if (execute)

		return !(read_iamr() & (IAMR_EX_BIT << pkey_shift));

		return !(current_thread_iamr() & (IAMR_EX_BIT << pkey_shift));



	amr = read_amr();

	amr = current_thread_amr();

	if (write)

		return !(amr & (AMR_WR_BIT << pkey_shift));