Commit 4a1948d6 authored by Russell King's avatar Russell King Committed by Greg Kroah-Hartman
Browse files

ARM: spectre-v1: use get_user() for __get_user()

Commit b1cd0a14

 upstream.

Fixing __get_user() for spectre variant 1 is not sane: we would have to
add address space bounds checking in order to validate that the location
should be accessed, and then zero the address if found to be invalid.

Since __get_user() is supposed to avoid the bounds check, and this is
exactly what get_user() does, there's no point having two different
implementations that are doing the same thing.  So, when the Spectre
workarounds are required, make __get_user() an alias of get_user().
Acked-by: default avatarMark Rutland <mark.rutland@arm.com>
Signed-off-by: default avatarRussell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: default avatarDavid A. Long <dave.long@linaro.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent f64824a3
......@@ -250,6 +250,16 @@ static inline void set_fs(mm_segment_t fs)
#define user_addr_max() \
(uaccess_kernel() ? ~0UL : get_fs())
#ifdef CONFIG_CPU_SPECTRE
/*
* When mitigating Spectre variant 1, it is not worth fixing the non-
* verifying accessors, because we need to add verification of the
* address space there. Force these to use the standard get_user()
* version instead.
*/
#define __get_user(x, ptr) get_user(x, ptr)
#else
/*
* The "__xxx" versions of the user access functions do not verify the
* address space - it must have been done previously with a separate
......@@ -266,12 +276,6 @@ static inline void set_fs(mm_segment_t fs)
__gu_err; \
})
#define __get_user_error(x, ptr, err) \
({ \
__get_user_err((x), (ptr), err); \
(void) 0; \
})
#define __get_user_err(x, ptr, err) \
do { \
unsigned long __gu_addr = (unsigned long)(ptr); \
......@@ -331,6 +335,7 @@ do { \
#define __get_user_asm_word(x, addr, err) \
__get_user_asm(x, addr, err, ldr)
#endif
#define __put_user_switch(x, ptr, __err, __fn) \
......
Markdown is supported
0% or .
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment