Commit d5fa30e6 authored by Aneesh Kumar K.V's avatar Aneesh Kumar K.V Committed by Michael Ellerman
Browse files

powerpc/book3s64/pkeys: Reset userspace AMR correctly on exec 



On fork, we inherit from the parent and on exec, we should switch to default_amr values.

Also, avoid changing the AMR register value within the kernel. The kernel now runs with
different AMR values.

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/20201127044424.40686-13-aneesh.kumar@linux.ibm.com
parent f643fcab

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

+2 −0
Original line number Diff line number Diff line
@@ -6,6 +6,8 @@ 
#include <asm/book3s/64/hash-pkey.h>



extern u64 __ro_after_init default_uamor;

extern u64 __ro_after_init default_amr;

extern u64 __ro_after_init default_iamr;



static inline u64 vmflag_to_pte_pkey_bits(u64 vm_flags)

{

arch/powerpc/kernel/process.c

+5 −1
Original line number Diff line number Diff line
@@ -1546,6 +1546,11 @@ void arch_setup_new_exec(void) 
		struct pt_regs *regs = task_stack_page(current) + THREAD_SIZE;

		current->thread.regs = regs - 1;

	}



#ifdef CONFIG_PPC_MEM_KEYS

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

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

#endif

}



#ifdef CONFIG_PPC64
@@ -1895,7 +1900,6 @@ void start_thread(struct pt_regs *regs, unsigned long start, unsigned long sp) 
	current->thread.load_tm = 0;

#endif /* CONFIG_PPC_TRANSACTIONAL_MEM */



	thread_pkey_regs_init(&current->thread);

}

EXPORT_SYMBOL(start_thread);

arch/powerpc/mm/book3s64/pkeys.c

+2 −14
Original line number Diff line number Diff line
@@ -28,8 +28,8 @@ static u32 initial_allocation_mask __ro_after_init; 
 * Even if we allocate keys with sys_pkey_alloc(), we need to make sure

 * other thread still find the access denied using the same keys.

 */

static u64 default_amr = ~0x0UL;

static u64 default_iamr = 0x5555555555555555UL;

u64 default_amr __ro_after_init  = ~0x0UL;

u64 default_iamr __ro_after_init = 0x5555555555555555UL;

u64 default_uamor __ro_after_init;

/*

 * Key used to implement PROT_EXEC mmap. Denies READ/WRITE
@@ -396,18 +396,6 @@ void thread_pkey_regs_restore(struct thread_struct *new_thread, 
		write_iamr(new_thread->iamr);

}



void thread_pkey_regs_init(struct thread_struct *thread)

{

	if (!mmu_has_feature(MMU_FTR_PKEY))

		return;



	thread->amr   = default_amr;

	thread->iamr  = default_iamr;



	write_amr(default_amr);

	write_iamr(default_iamr);

}



int execute_only_pkey(struct mm_struct *mm)

{

	return mm->context.execute_only_pkey;