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authorArnd Bergmann <arnd@arndb.de>2022-02-15 17:55:04 +0100
committerArnd Bergmann <arnd@arndb.de>2022-02-25 09:36:05 +0100
commit12700c17fc286149324f92d6d380bc48e43f253d (patch)
tree63157067b99d0adec5db4058ab9235b4802d1e49 /arch/Kconfig
parent23fc539e81295b14b50c6ccc5baeb4f3d59d822d (diff)
uaccess: generalize access_ok()
There are many different ways that access_ok() is defined across architectures, but in the end, they all just compare against the user_addr_max() value or they accept anything. Provide one definition that works for most architectures, checking against TASK_SIZE_MAX for user processes or skipping the check inside of uaccess_kernel() sections. For architectures without CONFIG_SET_FS(), this should be the fastest check, as it comes down to a single comparison of a pointer against a compile-time constant, while the architecture specific versions tend to do something more complex for historic reasons or get something wrong. Type checking for __user annotations is handled inconsistently across architectures, but this is easily simplified as well by using an inline function that takes a 'const void __user *' argument. A handful of callers need an extra __user annotation for this. Some architectures had trick to use 33-bit or 65-bit arithmetic on the addresses to calculate the overflow, however this simpler version uses fewer registers, which means it can produce better object code in the end despite needing a second (statically predicted) branch. Reviewed-by: Christoph Hellwig <hch@lst.de> Acked-by: Mark Rutland <mark.rutland@arm.com> [arm64, asm-generic] Acked-by: Geert Uytterhoeven <geert@linux-m68k.org> Acked-by: Stafford Horne <shorne@gmail.com> Acked-by: Dinh Nguyen <dinguyen@kernel.org> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Diffstat (limited to 'arch/Kconfig')
-rw-r--r--arch/Kconfig7
1 files changed, 7 insertions, 0 deletions
diff --git a/arch/Kconfig b/arch/Kconfig
index 678a80713b21..fa5db36bda67 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -898,6 +898,13 @@ config HAVE_SOFTIRQ_ON_OWN_STACK
Architecture provides a function to run __do_softirq() on a
separate stack.
+config ALTERNATE_USER_ADDRESS_SPACE
+ bool
+ help
+ Architectures set this when the CPU uses separate address
+ spaces for kernel and user space pointers. In this case, the
+ access_ok() check on a __user pointer is skipped.
+
config PGTABLE_LEVELS
int
default 2