Re: [PATCH 1/7] arm64: uaccess: Add batched kernel nofault accessors
From: bot+bpf-ci@kernel.org
Date: 2026-08-24 17:02:49
Also in:
bpf, linux-mm, lkml
quoted hunk ↗ jump to hunk
diff --git a/arch/arm64/include/asm/uaccess.h b/arch/arm64/include/asm/uaccess.h index 9f5bd9c69c24..1a14eb2a51dc 100644 --- a/arch/arm64/include/asm/uaccess.h +++ b/arch/arm64/include/asm/uaccess.h@@ -270,28 +270,43 @@ do { \ #define get_user __get_user /* - * We must not call into the scheduler between __mte_enable_tco_async() and - * __mte_disable_tco_async(). As `dst` and `src` may contain blocking - * functions, we must evaluate these outside of the critical section. + * Nofault load without TCO management for use inside a + * __begin/__end_kernel_nofault_bare() region. */ -#define __get_kernel_nofault(dst, src, type, err_label) \ +#define __get_kernel_nofault_bare(dst, src, type, err_label) \ do { \ __typeof__(dst) __gkn_dst = (dst); \ __typeof__(src) __gkn_src = (src); \ do { \ __label__ __gkn_label; \ - \ - __mte_enable_tco_async(); \ __raw_get_mem("ldr", *((type *)(__gkn_dst)), \ (__force type *)(__gkn_src), __gkn_label, K); \ - __mte_disable_tco_async(); \ break; \ __gkn_label: \ - __mte_disable_tco_async(); \ goto err_label; \ } while (0); \ } while (0) /* + * We must not call into the scheduler between __mte_enable_tco_async() and + * __mte_disable_tco_async(). As dst and src may contain blocking functions, + * evaluate them before overriding TCO. + */ +#define __get_kernel_nofault(dst, src, type, err_label) \ +do { \ + __label__ __gkn_tco_err; \ + __typeof__(dst) __gkn_tco_dst = (dst); \ + __typeof__(src) __gkn_tco_src = (src); \ + __mte_enable_tco_async(); \ + __get_kernel_nofault_bare(__gkn_tco_dst, __gkn_tco_src, type, \ + __gkn_tco_err); \ + __mte_disable_tco_async(); \ + break; \ +__gkn_tco_err: \ + __mte_disable_tco_async(); \ + goto err_label; \ +} while (0)
This isn't a bug, but the get and put variants now carry the same rule in two different wordings - would it read better to keep the two comments identical, or to have the put side just point at the get side? The comment above __get_kernel_nofault says "As dst and src may contain blocking functions, evaluate them before overriding TCO," while the comment above __put_kernel_nofault keeps the original "As `dst` and `src` may contain blocking functions, we must evaluate these outside of the critical section" - including the backticks that the get variant dropped. Also, should the wrapped argument line up under the open paren here (four tabs plus two spaces rather than five)?
+ __get_kernel_nofault_bare(__gkn_tco_dst, __gkn_tco_src, type, \ + __gkn_tco_err); \
The continuation line sits at column 37, while the open parenthesis of __get_kernel_nofault_bare( sits at column 34. The same three-column offset appears in __put_kernel_nofault at line 412. [ ... ]
quoted hunk ↗ jump to hunk
@@ -366,28 +381,48 @@ do { \ #define put_user __put_user -/* - * We must not call into the scheduler between __mte_enable_tco_async() and - * __mte_disable_tco_async(). As `dst` and `src` may contain blocking - * functions, we must evaluate these outside of the critical section. - */ -#define __put_kernel_nofault(dst, src, type, err_label) \ +/* Nofault store without TCO management; see __get_kernel_nofault_bare. */ +#define __put_kernel_nofault_bare(dst, src, type, err_label) \ do { \ __typeof__(dst) __pkn_dst = (dst); \ __typeof__(src) __pkn_src = (src); \ \ do { \ __label__ __pkn_err; \ - __mte_enable_tco_async(); \ __raw_put_mem("str", *((type *)(__pkn_src)), \ (__force type *)(__pkn_dst), __pkn_err, K); \ - __mte_disable_tco_async(); \ break; \ __pkn_err: \ - __mte_disable_tco_async(); \ goto err_label; \ } while (0); \ -} while(0) +} while (0) + +/* + * We must not call into the scheduler between __mte_enable_tco_async() and + * __mte_disable_tco_async(). As `dst` and `src` may contain blocking + * functions, we must evaluate these outside of the critical section. + */
[ ... ] --- AI reviewed your patch. Please fix the bug or email reply why it's not a bug. See: https://github.com/kernel-patches/vmtest/blob/master/ci/claude/README.md CI run summary: https://github.com/kernel-patches/bpf/actions/runs/32751368606