Commit 5fbc09eb authored by Christophe Leroy's avatar Christophe Leroy Committed by Madhavan Srinivasan
Browse files

powerpc/uaccess: Move barrier_nospec() out of allow_read_{from/write}_user() 



Commit 74e19ef0 ("uaccess: Add speculation barrier to
copy_from_user()") added a redundant barrier_nospec() in
copy_from_user(), because powerpc is already calling
barrier_nospec() in allow_read_from_user() and
allow_read_write_user(). But on other architectures that
call to barrier_nospec() was missing. So change powerpc
instead of reverting the above commit and having to fix
other architectures one by one. This is now possible
because barrier_nospec() has also been added in
copy_from_user_iter().

Move barrier_nospec() out of allow_read_from_user() and
allow_read_write_user(). This will also allow reuse of those
functions when implementing masked user access which doesn't
require barrier_nospec().

Don't add it back in raw_copy_from_user() as it is already called
by copy_from_user() and copy_from_user_iter().

Fixes: 74e19ef0 ("uaccess: Add speculation barrier to copy_from_user()")
Signed-off-by: default avatarChristophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: default avatarMadhavan Srinivasan <maddy@linux.ibm.com>
Link: https://patch.msgid.link/f29612105c5fcbc8ceb7303808ddc1a781f0f6b5.1766574657.git.chleroy@kernel.org
parent 9ace4753

arch/powerpc/include/asm/kup.h

+0 −2
Original line number Diff line number Diff line
@@ -134,7 +134,6 @@ static __always_inline void kuap_assert_locked(void) 


static __always_inline void allow_read_from_user(const void __user *from, unsigned long size)

{

	barrier_nospec();

	allow_user_access(NULL, from, size, KUAP_READ);

}
@@ -146,7 +145,6 @@ static __always_inline void allow_write_to_user(void __user *to, unsigned long s 
static __always_inline void allow_read_write_user(void __user *to, const void __user *from,

						  unsigned long size)

{

	barrier_nospec();

	allow_user_access(to, from, size, KUAP_READ_WRITE);

}

arch/powerpc/include/asm/uaccess.h

+4 −0
Original line number Diff line number Diff line
@@ -301,6 +301,7 @@ do { \ 
	__typeof__(sizeof(*(ptr))) __gu_size = sizeof(*(ptr));	\

								\

	might_fault();					\

	barrier_nospec();					\

	allow_read_from_user(__gu_addr, __gu_size);		\

	__get_user_size_allowed(__gu_val, __gu_addr, __gu_size, __gu_err);	\

	prevent_read_from_user(__gu_addr, __gu_size);		\
@@ -329,6 +330,7 @@ raw_copy_in_user(void __user *to, const void __user *from, unsigned long n) 
{

	unsigned long ret;



	barrier_nospec();

	allow_read_write_user(to, from, n);

	ret = __copy_tofrom_user(to, from, n);

	prevent_read_write_user(to, from, n);
@@ -415,6 +417,7 @@ static __must_check __always_inline bool user_access_begin(const void __user *pt 


	might_fault();



	barrier_nospec();

	allow_read_write_user((void __user *)ptr, ptr, len);

	return true;

}
@@ -431,6 +434,7 @@ user_read_access_begin(const void __user *ptr, size_t len) 


	might_fault();



	barrier_nospec();

	allow_read_from_user(ptr, len);

	return true;

}