From: Dave Hansen <dave.hansen@intel.com>
To: Rick Edgecombe <rick.p.edgecombe@intel.com>,
Liam.Howlett@oracle.com, akpm@linux-foundation.org,
debug@rivosinc.com, broonie@kernel.org,
kirill.shutemov@linux.intel.com, keescook@chromium.org,
tglx@linutronix.de, mingo@redhat.com, bp@alien8.de,
dave.hansen@linux.intel.com, x86@kernel.org, luto@kernel.org,
peterz@infradead.org, hpa@zytor.com, linux-mm@kvack.org,
linux-kernel@vger.kernel.org
Subject: Re: [RFC PATCH 1/8] mm: Switch mm->get_unmapped_area() to a flag
Date: Thu, 15 Feb 2024 16:30:46 -0800 [thread overview]
Message-ID: <acac6cc8-fd83-4541-8310-63f37cd41fa6@intel.com> (raw)
In-Reply-To: <20240215231332.1556787-2-rick.p.edgecombe@intel.com>
On 2/15/24 15:13, Rick Edgecombe wrote:
> The mm_struct contains a function pointer *get_unmapped_area(), which
> is set to either arch_get_unmapped_area() or
> arch_get_unmapped_area_topdown() during the initialization of the mm.
>
> Since the function pointer only ever points to two functions that are named
> the same across all arch's, a function pointer is not really required. In
> addition future changes will want to add versions of the functions that
> take additional arguments. So to save a pointers worth of bytes in
> mm_struct, and prevent adding additional function pointers to mm_struct in
> future changes, remove it and keep the information about which
> get_unmapped_area() to use in a flag.
Indirect calls are just all kinds of evil, especially when Spectre-v2 is
in play. This is a really good idea.
Acked-by: Dave Hansen <dave.hansen@linux.intel.com>
next prev parent reply other threads:[~2024-02-16 0:30 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-02-15 23:13 [RFC PATCH 0/8] Cover a guard gap corner case Rick Edgecombe
2024-02-15 23:13 ` [RFC PATCH 1/8] mm: Switch mm->get_unmapped_area() to a flag Rick Edgecombe
2024-02-16 0:30 ` Dave Hansen [this message]
2024-02-16 2:15 ` Liam R. Howlett
2024-02-16 12:30 ` Kirill A. Shutemov
2024-02-16 21:42 ` Edgecombe, Rick P
2024-02-21 7:10 ` Mike Rapoport
2024-02-21 16:59 ` Edgecombe, Rick P
2024-02-15 23:13 ` [RFC PATCH 2/8] mm: Introduce arch_get_unmapped_area_vmflags() Rick Edgecombe
2024-02-15 23:13 ` [RFC PATCH 3/8] mm: Use get_unmapped_area_vmflags() Rick Edgecombe
2024-02-16 12:56 ` Kirill A. Shutemov
2024-02-16 22:15 ` Edgecombe, Rick P
2024-02-17 12:35 ` kirill.shutemov
2024-02-15 23:13 ` [RFC PATCH 4/8] thp: Add thp_get_unmapped_area_vmflags() Rick Edgecombe
2024-02-16 12:59 ` Kirill A. Shutemov
2024-02-16 22:21 ` Edgecombe, Rick P
2024-02-17 12:57 ` kirill.shutemov
2024-02-15 23:13 ` [RFC PATCH 5/8] mm: Take placement mappings gap into account Rick Edgecombe
2024-02-16 13:12 ` Kirill A. Shutemov
2024-02-17 1:11 ` Edgecombe, Rick P
2024-02-20 16:48 ` Edgecombe, Rick P
2024-02-15 23:13 ` [RFC PATCH 6/8] x86/mm: Implement HAVE_ARCH_UNMAPPED_AREA_VMFLAGS Rick Edgecombe
2024-02-15 23:13 ` [RFC PATCH 7/8] x86/mm: Care about shadow stack guard gap during placement Rick Edgecombe
2024-02-15 23:13 ` [RFC PATCH 8/8] selftests/x86: Add placement guard gap test for shstk Rick Edgecombe
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