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author | James Morse <james.morse@arm.com> | 2018-10-10 18:55:44 +0300 |
---|---|---|
committer | Catalin Marinas <catalin.marinas@arm.com> | 2018-10-10 19:52:08 +0300 |
commit | 3b82a6ea23277f56c4f005872bb73c8ce29779d7 (patch) | |
tree | 9b9a4e0faa0221fbb22aee5a214424ba784d0e63 /arch/arm64/include/asm/uaccess.h | |
parent | 742fafa50b62cb9f379ba14a13443f52afdc0c5d (diff) | |
download | linux-3b82a6ea23277f56c4f005872bb73c8ce29779d7.tar.xz |
Revert "arm64: uaccess: implement unsafe accessors"
This reverts commit a1f33941f7e103bcf471eaf8461b212223c642d6.
The unsafe accessors allow the PAN enable/disable calls to be made
once for a group of accesses. Adding these means we can now have
sequences that look like this:
| user_access_begin();
| unsafe_put_user(static-value, x, err);
| unsafe_put_user(helper-that-sleeps(), x, err);
| user_access_end();
Calling schedule() without taking an exception doesn't switch the
PSTATE or TTBRs. We can switch out of a uaccess-enabled region, and
run other code with uaccess enabled for a different thread.
We can also switch from uaccess-disabled code back into this region,
meaning the unsafe_put_user()s will fault.
For software-PAN, threads that do this will get stuck as
handle_mm_fault() will determine the page has already been mapped in,
but we fault again as the page tables aren't loaded.
To solve this we need code in __switch_to() that save/restores the
PAN state.
Acked-by: Julien Thierry <julien.thierry@arm.com>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: James Morse <james.morse@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Diffstat (limited to 'arch/arm64/include/asm/uaccess.h')
-rw-r--r-- | arch/arm64/include/asm/uaccess.h | 61 |
1 files changed, 15 insertions, 46 deletions
diff --git a/arch/arm64/include/asm/uaccess.h b/arch/arm64/include/asm/uaccess.h index 8ac6e34922e7..07c34087bd5e 100644 --- a/arch/arm64/include/asm/uaccess.h +++ b/arch/arm64/include/asm/uaccess.h @@ -276,9 +276,11 @@ static inline void __user *__uaccess_mask_ptr(const void __user *ptr) : "+r" (err), "=&r" (x) \ : "r" (addr), "i" (-EFAULT)) -#define __get_user_err_unsafe(x, ptr, err) \ +#define __get_user_err(x, ptr, err) \ do { \ unsigned long __gu_val; \ + __chk_user_ptr(ptr); \ + uaccess_enable_not_uao(); \ switch (sizeof(*(ptr))) { \ case 1: \ __get_user_asm("ldrb", "ldtrb", "%w", __gu_val, (ptr), \ @@ -299,24 +301,17 @@ do { \ default: \ BUILD_BUG(); \ } \ - (x) = (__force __typeof__(*(ptr)))__gu_val; \ -} while (0) - -#define __get_user_err_check(x, ptr, err) \ -do { \ - __chk_user_ptr(ptr); \ - uaccess_enable_not_uao(); \ - __get_user_err_unsafe((x), (ptr), (err)); \ uaccess_disable_not_uao(); \ + (x) = (__force __typeof__(*(ptr)))__gu_val; \ } while (0) -#define __get_user_err(x, ptr, err, accessor) \ +#define __get_user_check(x, ptr, err) \ ({ \ __typeof__(*(ptr)) __user *__p = (ptr); \ might_fault(); \ if (access_ok(VERIFY_READ, __p, sizeof(*__p))) { \ __p = uaccess_mask_ptr(__p); \ - accessor((x), __p, (err)); \ + __get_user_err((x), __p, (err)); \ } else { \ (x) = 0; (err) = -EFAULT; \ } \ @@ -324,14 +319,14 @@ do { \ #define __get_user_error(x, ptr, err) \ ({ \ - __get_user_err((x), (ptr), (err), __get_user_err_check); \ + __get_user_check((x), (ptr), (err)); \ (void)0; \ }) #define __get_user(x, ptr) \ ({ \ int __gu_err = 0; \ - __get_user_err((x), (ptr), __gu_err, __get_user_err_check); \ + __get_user_check((x), (ptr), __gu_err); \ __gu_err; \ }) @@ -351,9 +346,11 @@ do { \ : "+r" (err) \ : "r" (x), "r" (addr), "i" (-EFAULT)) -#define __put_user_err_unsafe(x, ptr, err) \ +#define __put_user_err(x, ptr, err) \ do { \ __typeof__(*(ptr)) __pu_val = (x); \ + __chk_user_ptr(ptr); \ + uaccess_enable_not_uao(); \ switch (sizeof(*(ptr))) { \ case 1: \ __put_user_asm("strb", "sttrb", "%w", __pu_val, (ptr), \ @@ -374,24 +371,16 @@ do { \ default: \ BUILD_BUG(); \ } \ -} while (0) - - -#define __put_user_err_check(x, ptr, err) \ -do { \ - __chk_user_ptr(ptr); \ - uaccess_enable_not_uao(); \ - __put_user_err_unsafe((x), (ptr), (err)); \ uaccess_disable_not_uao(); \ } while (0) -#define __put_user_err(x, ptr, err, accessor) \ +#define __put_user_check(x, ptr, err) \ ({ \ __typeof__(*(ptr)) __user *__p = (ptr); \ might_fault(); \ if (access_ok(VERIFY_WRITE, __p, sizeof(*__p))) { \ __p = uaccess_mask_ptr(__p); \ - accessor((x), __p, (err)); \ + __put_user_err((x), __p, (err)); \ } else { \ (err) = -EFAULT; \ } \ @@ -399,39 +388,19 @@ do { \ #define __put_user_error(x, ptr, err) \ ({ \ - __put_user_err((x), (ptr), (err), __put_user_err_check); \ + __put_user_check((x), (ptr), (err)); \ (void)0; \ }) #define __put_user(x, ptr) \ ({ \ int __pu_err = 0; \ - __put_user_err((x), (ptr), __pu_err, __put_user_err_check); \ + __put_user_check((x), (ptr), __pu_err); \ __pu_err; \ }) #define put_user __put_user - -#define user_access_begin() uaccess_enable_not_uao() -#define user_access_end() uaccess_disable_not_uao() - -#define unsafe_get_user(x, ptr, err) \ -do { \ - int __gu_err = 0; \ - __get_user_err((x), (ptr), __gu_err, __get_user_err_unsafe); \ - if (__gu_err != 0) \ - goto err; \ -} while (0) - -#define unsafe_put_user(x, ptr, err) \ -do { \ - int __pu_err = 0; \ - __put_user_err((x), (ptr), __pu_err, __put_user_err_unsafe); \ - if (__pu_err != 0) \ - goto err; \ -} while (0) - extern unsigned long __must_check __arch_copy_from_user(void *to, const void __user *from, unsigned long n); #define raw_copy_from_user(to, from, n) \ ({ \ |