github-mirror/linux
1
0
Fork 0
mirror of https://github.com/torvalds/linux.git synced 2026-07-27 17:47:41 +02:00
Code Issues Actions Packages Projects Releases Wiki Activity Graph

arm64: mm: Complete the PTE store in ptep_try_set()

Browse Source 
ptep_try_set() installs a kernel PTE with try_cmpxchg() but, unlike
__set_pte(), skips the barriers that arm64 requires after writing a valid
kernel PTE. Without them a subsequent access can fault instead of seeing
the new mapping.

Issue them with emit_pte_barriers() rather than __set_pte_complete().
ptep_try_set() must finish the store before it returns, but
__set_pte_complete() would defer the barriers when the calling context is in
lazy MMU mode.

v2: Emit the barriers directly instead of __set_pte_complete(). (Catalin)

Fixes: 258df8fce4 ("mm: Add ptep_try_set() for lockless empty-slot installs")
Suggested-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Link: https://lore.kernel.org/all/aiRFcz78QTZdIHHB@arm.com/
Link: https://lore.kernel.org/bpf/7f5f7c94601312c1a401fb18998291cc@kernel.org
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
This commit is contained in:
Tejun Heo 2026-06-07 21:25:47 -10:00 committed by Kumar Kartikeya Dwivedi
parent 63a6f3bc62
commit 71385b78db
No known key found for this signature in database
GPG Key ID: 472D377B63542F83
1 changed files with 10 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

11
arch/arm64/include/asm/pgtable.h
View File

@ -1838,7 +1838,16 @@ static inline bool ptep_try_set(pte_t *ptep, pte_t new_pte)
{
pteval_t old = 0;
return try_cmpxchg(&pte_val(*ptep), &old, pte_val(new_pte));
if (!try_cmpxchg(&pte_val(*ptep), &old, pte_val(new_pte)))
return false;
/*
* The store must be complete by the time this returns, but the caller
* may be in lazy MMU mode, where __set_pte_complete() would defer the
* barriers. Issue them directly.
*/
emit_pte_barriers();
return true;
}
#define ptep_try_set ptep_try_set