From: Muhammad Usama Anjum <usama.anjum@arm.com>
To: Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will@kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Andrii Nakryiko <andrii@kernel.org>,
Eduard Zingerman <eddyz87@gmail.com>,
Kumar Kartikeya Dwivedi <memxor@gmail.com>,
Martin KaFai Lau <martin.lau@linux.dev>,
Song Liu <song@kernel.org>,
Yonghong Song <yonghong.song@linux.dev>,
Jiri Olsa <jolsa@kernel.org>,
Emil Tsalapatis <emil@etsalapatis.com>,
Ihor Solodrai <ihor.solodrai@linux.dev>,
Andrew Morton <akpm@linux-foundation.org>,
David Hildenbrand <david@kernel.org>,
Lorenzo Stoakes <ljs@kernel.org>,
"Liam R. Howlett" <liam@infradead.org>,
Vlastimil Babka <vbabka@kernel.org>,
Mike Rapoport <rppt@kernel.org>,
Suren Baghdasaryan <surenb@google.com>,
Michal Hocko <mhocko@suse.com>,
linux-arm-kernel@lists.infradead.org (moderated list:ARM64 PORT
(AARCH64 ARCHITECTURE)), linux-kernel@vger.kernel.org (open list),
bpf@vger.kernel.org (open list:BPF [GENERAL] (Safe Dynamic
Programs and Tools)),
linux-mm@kvack.org (open list:MEMORY MANAGEMENT - CORE)
Cc: Muhammad Usama Anjum <usama.anjum@arm.com>
Subject: [PATCH 2/7] uaccess: Add scope guard for bare kernel nofault regions
Date: Mon, 24 Aug 2026 17:04:47 +0100 [thread overview]
Message-ID: <20260824160523.3907021-3-usama.anjum@arm.com> (raw)
In-Reply-To: <20260824160523.3907021-1-usama.anjum@arm.com>
A batched nofault region must run its end hook on every exit. Pairing the
hooks by hand makes early returns and error paths easy to get wrong.
Add a scope guard that starts the region on entry and ends it when the
scope is left. Callers can keep their natural control flow while the
architecture state remains balanced on success and failure.
No functional change until a caller uses the guard.
Signed-off-by: Muhammad Usama Anjum <usama.anjum@arm.com>
---
include/linux/uaccess.h | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/include/linux/uaccess.h b/include/linux/uaccess.h
index 7ae1854673471..b25e778ddc38a 100644
--- a/include/linux/uaccess.h
+++ b/include/linux/uaccess.h
@@ -653,6 +653,10 @@ do { \
#define __end_kernel_nofault_bare() do {} while (0)
#endif
+DEFINE_LOCK_GUARD_0(__kernel_nofault_bare,
+ __begin_kernel_nofault_bare(),
+ __end_kernel_nofault_bare())
+
/**
* get_kernel_nofault(): safely attempt to read from a location
* @val: read into this variable
--
2.47.3
next prev parent reply other threads:[~2026-08-24 16:06 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-08-24 16:04 [PATCH 0/7] arm64: Batch PSTATE.TCO handling in kernel nofault loops Muhammad Usama Anjum
2026-08-24 16:04 ` [PATCH 1/7] arm64: uaccess: Add batched kernel nofault accessors Muhammad Usama Anjum
2026-08-24 17:02 ` bot+bpf-ci
2026-08-24 16:04 ` Muhammad Usama Anjum [this message]
2026-08-24 17:02 ` [PATCH 2/7] uaccess: Add scope guard for bare kernel nofault regions bot+bpf-ci
2026-08-24 16:04 ` [PATCH 3/7] maccess: Skip setup for zero-sized kernel nofault copies Muhammad Usama Anjum
2026-08-24 17:02 ` bot+bpf-ci
2026-08-24 16:04 ` [PATCH 4/7] maccess: Use a scoped guard for page faults Muhammad Usama Anjum
2026-08-24 17:02 ` bot+bpf-ci
2026-08-25 10:36 ` David Hildenbrand (Arm)
2026-08-25 12:07 ` Muhammad Usama Anjum
2026-08-24 16:04 ` [PATCH 4/7] maccess: Use a scoped guard to re-enable " Muhammad Usama Anjum
2026-08-24 16:04 ` [PATCH 5/7] maccess: Batch TCO handling in kernel nofault loops Muhammad Usama Anjum
2026-08-24 17:02 ` bot+bpf-ci
2026-08-24 16:04 ` [PATCH 6/7] bpf: Skip setup for zero-length string kfunc operations Muhammad Usama Anjum
2026-08-24 16:04 ` [PATCH 7/7] bpf: Batch TCO handling in string kfuncs Muhammad Usama Anjum
2026-08-24 17:02 ` bot+bpf-ci
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