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authorLinus Torvalds <torvalds@linux-foundation.org>2021-02-11 15:41:07 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2021-02-11 15:41:07 -0800
commitdcc0b49040c70ad827a7f3d58a21b01fdb14e749 (patch)
tree4f8024e086e9f7bfeb8eeab052481a51593b90ac /arch
parentc05263df6c1ab82277cc3b2778b183b469a71a60 (diff)
parent8c511eff1827239f24ded212b1bcda7ca5b16203 (diff)
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
Diffstat (limited to 'arch')
-rw-r--r--arch/powerpc/include/asm/book3s/64/kup.h16
-rw-r--r--arch/powerpc/include/asm/book3s/64/pkeys.h4
-rw-r--r--arch/powerpc/mm/book3s64/pkeys.c1
3 files changed, 12 insertions, 9 deletions
diff --git a/arch/powerpc/include/asm/book3s/64/kup.h b/arch/powerpc/include/asm/book3s/64/kup.h
index f50f72e535aa..7d1ef7b9754e 100644
--- a/arch/powerpc/include/asm/book3s/64/kup.h
+++ b/arch/powerpc/include/asm/book3s/64/kup.h
@@ -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 */
diff --git a/arch/powerpc/include/asm/book3s/64/pkeys.h b/arch/powerpc/include/asm/book3s/64/pkeys.h
index 3b8640498f5b..5b178139f3c0 100644
--- a/arch/powerpc/include/asm/book3s/64/pkeys.h
+++ b/arch/powerpc/include/asm/book3s/64/pkeys.h
@@ -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))
diff --git a/arch/powerpc/mm/book3s64/pkeys.c b/arch/powerpc/mm/book3s64/pkeys.c
index f1c6f264ed91..15dcc5ad91c5 100644
--- a/arch/powerpc/mm/book3s64/pkeys.c
+++ b/arch/powerpc/mm/book3s64/pkeys.c
@@ -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.