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

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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: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Reviewed-by: Sandipan Das <sandipan@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20201127044424.40686-13-aneesh.kumar@linux.ibm.com
This commit is contained in:
Aneesh Kumar K.V 2020-11-27 10:14:14 +05:30 committed by Michael Ellerman
parent f643fcab74
commit d5fa30e699
3 changed files with 9 additions and 15 deletions
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2
arch/powerpc/include/asm/book3s/64/pkeys.h
View file

@ -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)
{

6
arch/powerpc/kernel/process.c
View file

@ -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);

16
arch/powerpc/mm/book3s64/pkeys.c
View file

@ -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;