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powerpc fixes for 5.11 #8

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One fix for a regression seen in io_uring, introduced by our support for KUAP
 (Kernel User Access Prevention) with the Hash MMU.
 
 Thanks to: Aneesh Kumar K.V, Zorro Lang.
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Merge tag 'powerpc-5.11-8' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux

Pull powerpc fix from Michael Ellerman:
 "One fix for a regression seen in io_uring, introduced by our support
  for KUAP (Kernel User Access Prevention) with the Hash MMU.

  Thanks to Aneesh Kumar K.V, and Zorro Lang"

* tag 'powerpc-5.11-8' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux:
  powerpc/kuap: Allow kernel thread to access userspace after kthread_use_mm
This commit is contained in:
Linus Torvalds 2021-02-11 15:41:07 -08:00
commit dcc0b49040
3 changed files with 12 additions and 9 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

16
arch/powerpc/include/asm/book3s/64/kup.h
View File

@ -199,25 +199,31 @@ DECLARE_STATIC_KEY_FALSE(uaccess_flush_key);
#ifdef CONFIG_PPC_PKEY
extern u64 __ro_after_init default_uamor;
extern u64 __ro_after_init default_amr;
extern u64 __ro_after_init default_iamr;
#include <asm/mmu.h>
#include <asm/ptrace.h>
/*
* For kernel thread that doesn't have thread.regs return
* default AMR/IAMR values.
/* usage of kthread_use_mm() should inherit the
* AMR value of the operating address space. But, the AMR value is
* thread-specific and we inherit the address space and not thread
* access restrictions. Because of this ignore AMR value when accessing
* userspace via kernel thread.
*/
static inline u64 current_thread_amr(void)
{
if (current->thread.regs)
return current->thread.regs->amr;
return AMR_KUAP_BLOCKED;
return default_amr;
}
static inline u64 current_thread_iamr(void)
{
if (current->thread.regs)
return current->thread.regs->iamr;
return AMR_KUEP_BLOCKED;
return default_iamr;
}
#endif /* CONFIG_PPC_PKEY */

4
arch/powerpc/include/asm/book3s/64/pkeys.h
View File

@ -5,10 +5,6 @@
#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)
{
if (!mmu_has_feature(MMU_FTR_PKEY))

1
arch/powerpc/mm/book3s64/pkeys.c
View File

@ -31,6 +31,7 @@ static u32 initial_allocation_mask __ro_after_init;
u64 default_amr __ro_after_init = ~0x0UL;
u64 default_iamr __ro_after_init = 0x5555555555555555UL;
u64 default_uamor __ro_after_init;
EXPORT_SYMBOL(default_amr);
/*
* Key used to implement PROT_EXEC mmap. Denies READ/WRITE
* We pick key 2 because 0 is special key and 1 is reserved as per ISA.