forge/linux-uconsole
1
0
Fork 0
Code Issues 1 Pull requests Projects Releases Packages Wiki Activity Actions

BACKPORT: arm64: uaccess: rename privileged uaccess routines

Browse source 
We currently have many uaccess_*{enable,disable}*() variants, which
subsequent patches will cut down as part of removing set_fs() and
friends. Once this simplification is made, most uaccess routines will
only need to ensure that the user page tables are mapped in TTBR0, as is
currently dealt with by uaccess_ttbr0_{enable,disable}().

The existing uaccess_{enable,disable}() routines ensure that user page
tables are mapped in TTBR0, and also disable PAN protections, which is
necessary to be able to use atomics on user memory, but also permit
unrelated privileged accesses to access user memory.

As preparatory step, let's rename uaccess_{enable,disable}() to
uaccess_{enable,disable}_privileged(), highlighting this caveat and
discouraging wider misuse. Subsequent patches can reuse the
uaccess_{enable,disable}() naming for the common case of ensuring the
user page tables are mapped in TTBR0.

There should be no functional change as a result of this patch.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: James Morse <james.morse@arm.com>
Cc: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20201202131558.39270-5-mark.rutland@arm.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

Bug: 170327579
Bug: 172318110
(cherry picked from commit 923e1e7d82)
[glider: resolved minor conflicts in arch/arm64/include/asm/uaccess.h]
Signed-off-by: Alexander Potapenko <glider@google.com>
Change-Id: I15e3ba3b5b7b99ff93c42acf1aac17984094aebc
This commit is contained in:
Mark Rutland 2020-12-02 13:15:50 +00:00 • committed by Alexander Potapenko
commit 800a0f7b36
3 changed files with 8 additions and 8 deletions
Download patch file Download diff file Expand all files Collapse all files

8
arch/arm64/include/asm/futex.h
View file

@ -16,7 +16,7 @@
do { \
unsigned int loops = FUTEX_MAX_LOOPS; \
\
uaccess_enable(); \
uaccess_enable_privileged(); \
asm volatile( \
" prfm pstl1strm, %2\n" \
"1: ldxr %w1, %2\n" \
@ -39,7 +39,7 @@ do { \
"+r" (loops) \
: "r" (oparg), "Ir" (-EFAULT), "Ir" (-EAGAIN) \
: "memory"); \
uaccess_disable(); \
uaccess_disable_privileged(); \
} while (0)
static inline int
@ -95,7 +95,7 @@ futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *_uaddr,
return -EFAULT;
uaddr = __uaccess_mask_ptr(_uaddr);
uaccess_enable();
uaccess_enable_privileged();
asm volatile("// futex_atomic_cmpxchg_inatomic\n"
" prfm pstl1strm, %2\n"
"1: ldxr %w1, %2\n"
@ -118,7 +118,7 @@ futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *_uaddr,
: "+r" (ret), "=&r" (val), "+Q" (*uaddr), "=&r" (tmp), "+r" (loops)
: "r" (oldval), "r" (newval), "Ir" (-EFAULT), "Ir" (-EAGAIN)
: "memory");
uaccess_disable();
uaccess_disable_privileged();
if (!ret)
*uval = val;

4
arch/arm64/include/asm/uaccess.h
View file

@ -217,7 +217,7 @@ do { \
* The Tag check override (TCO) bit disables temporarily the tag checking
* preventing the issue.
*/
static inline void uaccess_disable(void)
static inline void uaccess_disable_privileged(void)
{
asm volatile(ALTERNATIVE("nop", SET_PSTATE_TCO(0),
ARM64_MTE, CONFIG_KASAN_HW_TAGS));
@ -225,7 +225,7 @@ static inline void uaccess_disable(void)
__uaccess_disable(ARM64_HAS_PAN);
}
static inline void uaccess_enable(void)
static inline void uaccess_enable_privileged(void)
{
asm volatile(ALTERNATIVE("nop", SET_PSTATE_TCO(1),
ARM64_MTE, CONFIG_KASAN_HW_TAGS));

4
arch/arm64/kernel/armv8_deprecated.c
View file

@ -277,7 +277,7 @@ static void __init register_insn_emulation_sysctl(void)
#define __user_swpX_asm(data, addr, res, temp, temp2, B) \
do { \
uaccess_enable(); \
uaccess_enable_privileged(); \
__asm__ __volatile__( \
" mov %w3, %w7\n" \
"0: ldxr"B" %w2, [%4]\n" \
@ -302,7 +302,7 @@ do { \
"i" (-EFAULT), \
"i" (__SWP_LL_SC_LOOPS) \
: "memory"); \
uaccess_disable(); \
uaccess_disable_privileged(); \
} while (0)
#define __user_swp_asm(data, addr, res, temp, temp2) \