On 12/11/2021 12:59 AM, Andrew Morton wrote:
On Fri, 10 Dec 2021 21:36:00 +0800 Tiezhu Yang <yangtiezhu@xxxxxxxxxxx> wrote:In arch/*/kernel/crash_dump*.c, there exist similar code about copy_oldmem_page(), move copy_to() from vmcore.c to uaccess.h, and then we can use copy_to() to simplify the related code. ... --- a/fs/proc/vmcore.c +++ b/fs/proc/vmcore.c @@ -238,20 +238,6 @@ copy_oldmem_page_encrypted(unsigned long pfn, char *buf, size_t csize, return copy_oldmem_page(pfn, buf, csize, offset, userbuf); } -/* - * Copy to either kernel or user space - */ -static int copy_to(void *target, void *src, size_t size, int userbuf) -{ - if (userbuf) { - if (copy_to_user((char __user *) target, src, size)) - return -EFAULT; - } else { - memcpy(target, src, size); - } - return 0; -} - #ifdef CONFIG_PROC_VMCORE_DEVICE_DUMP static int vmcoredd_copy_dumps(void *dst, u64 start, size_t size, int userbuf) { diff --git a/include/linux/uaccess.h b/include/linux/uaccess.h index ac03940..4a6c3e4 100644 --- a/include/linux/uaccess.h +++ b/include/linux/uaccess.h @@ -201,6 +201,20 @@ copy_to_user(void __user *to, const void *from, unsigned long n) return n; } +/* + * Copy to either kernel or user space + */ +static inline int copy_to(void *target, void *src, size_t size, int userbuf) +{ + if (userbuf) { + if (copy_to_user((char __user *) target, src, size)) + return -EFAULT; + } else { + memcpy(target, src, size); + } + return 0; +} +Ordinarily I'd say "this is too large to be inlined". But the function has only a single callsite per architecture so inlining it won't cause bloat at present. But hopefully copy_to() will get additional callers in the future, in which case it shouldn't be inlined. So I'm thinking it would be best to start out with this as a regular non-inlined function, in lib/usercopy.c. Also, copy_to() is a very poor name for a globally-visible helper function. Better would be copy_to_user_or_kernel(), although that's perhaps a bit long. And the `userbuf' arg should have type bool, yes?
Hi Andrew, Thank you very much for your reply and suggestion, I agree with you, I will send v2 later. Thanks, Tiezhu
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