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/sh/include/asm/uaccess.h | 22 ++-------------------- 1 file changed, 2 insertions(+), 20 deletions(-) (limited to 'arch/sh') diff --git a/arch/sh/include/asm/uaccess.h b/arch/sh/include/asm/uaccess.h index 8867bb04b00e..ccd219d74851 100644 --- a/arch/sh/include/asm/uaccess.h +++ b/arch/sh/include/asm/uaccess.h @@ -5,28 +5,10 @@ #include #include -#define __addr_ok(addr) \ - ((unsigned long __force)(addr) < current_thread_info()->addr_limit.seg) - -/* - * __access_ok: Check if address with size is OK or not. - * - * Uhhuh, this needs 33-bit arithmetic. We have a carry.. - * - * sum := addr + size; carry? --> flag = true; - * if (sum >= addr_limit) flag = true; - */ -#define __access_ok(addr, size) ({ \ - unsigned long __ao_a = (addr), __ao_b = (size); \ - unsigned long __ao_end = __ao_a + __ao_b - !!__ao_b; \ - __ao_end >= __ao_a && __addr_ok(__ao_end); }) - -#define access_ok(addr, size) \ - (__chk_user_ptr(addr), \ - __access_ok((unsigned long __force)(addr), (size))) - #define user_addr_max() (current_thread_info()->addr_limit.seg) +#include + /* * Uh, these should become the main single-value transfer routines ... * They automatically use the right size if we just have the right -- cgit v1.2.3