From 12700c17fc286149324f92d6d380bc48e43f253d Mon Sep 17 00:00:00 2001 From: Arnd Bergmann Date: Tue, 15 Feb 2022 17:55:04 +0100 Subject: 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 Acked-by: Mark Rutland [arm64, asm-generic] Acked-by: Geert Uytterhoeven Acked-by: Stafford Horne Acked-by: Dinh Nguyen Signed-off-by: Arnd Bergmann --- arch/Kconfig | 7 +++++++ 1 file changed, 7 insertions(+) (limited to 'arch/Kconfig') 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 -- cgit v1.2.3 From 967747bbc084b93b54e66f9047d342232314cd25 Mon Sep 17 00:00:00 2001 From: Arnd Bergmann Date: Fri, 11 Feb 2022 21:42:45 +0100 Subject: uaccess: remove CONFIG_SET_FS There are no remaining callers of set_fs(), so CONFIG_SET_FS can be removed globally, along with the thread_info field and any references to it. This turns access_ok() into a cheaper check against TASK_SIZE_MAX. As CONFIG_SET_FS is now gone, drop all remaining references to set_fs()/get_fs(), mm_segment_t, user_addr_max() and uaccess_kernel(). Acked-by: Sam Ravnborg # for sparc32 changes Acked-by: "Eric W. Biederman" Tested-by: Sergey Matyukevich # for arc changes Acked-by: Stafford Horne # [openrisc, asm-generic] Acked-by: Dinh Nguyen Signed-off-by: Arnd Bergmann --- arch/Kconfig | 3 --- 1 file changed, 3 deletions(-) (limited to 'arch/Kconfig') diff --git a/arch/Kconfig b/arch/Kconfig index fa5db36bda67..99349547afed 100644 --- a/arch/Kconfig +++ b/arch/Kconfig @@ -24,9 +24,6 @@ config KEXEC_ELF config HAVE_IMA_KEXEC bool -config SET_FS - bool - config HOTPLUG_SMT bool -- cgit v1.2.3