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Message-Id: <20240827-patches-below_hint_mmap-v1-10-46ff2eb9022d@rivosinc.com>
Date: Tue, 27 Aug 2024 22:49:16 -0700
From: Charlie Jenkins <charlie@...osinc.com>
To: Arnd Bergmann <arnd@...db.de>, Paul Walmsley <paul.walmsley@...ive.com>,
Palmer Dabbelt <palmer@...belt.com>, Albert Ou <aou@...s.berkeley.edu>,
Catalin Marinas <catalin.marinas@....com>, Will Deacon <will@...nel.org>,
Michael Ellerman <mpe@...erman.id.au>, Nicholas Piggin <npiggin@...il.com>,
Christophe Leroy <christophe.leroy@...roup.eu>,
Naveen N Rao <naveen@...nel.org>, Muchun Song <muchun.song@...ux.dev>,
Andrew Morton <akpm@...ux-foundation.org>,
"Liam R. Howlett" <Liam.Howlett@...cle.com>,
Vlastimil Babka <vbabka@...e.cz>,
Lorenzo Stoakes <lorenzo.stoakes@...cle.com>,
Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...hat.com>,
Borislav Petkov <bp@...en8.de>, Dave Hansen <dave.hansen@...ux.intel.com>,
x86@...nel.org, "H. Peter Anvin" <hpa@...or.com>,
Huacai Chen <chenhuacai@...nel.org>, WANG Xuerui <kernel@...0n.name>,
Russell King <linux@...linux.org.uk>,
Thomas Bogendoerfer <tsbogend@...ha.franken.de>,
"James E.J. Bottomley" <James.Bottomley@...senPartnership.com>,
Helge Deller <deller@....de>, Alexander Gordeev <agordeev@...ux.ibm.com>,
Gerald Schaefer <gerald.schaefer@...ux.ibm.com>,
Heiko Carstens <hca@...ux.ibm.com>, Vasily Gorbik <gor@...ux.ibm.com>,
Christian Borntraeger <borntraeger@...ux.ibm.com>,
Sven Schnelle <svens@...ux.ibm.com>,
Yoshinori Sato <ysato@...rs.sourceforge.jp>, Rich Felker <dalias@...c.org>,
John Paul Adrian Glaubitz <glaubitz@...sik.fu-berlin.de>,
"David S. Miller" <davem@...emloft.net>,
Andreas Larsson <andreas@...sler.com>, Shuah Khan <shuah@...nel.org>,
Alexandre Ghiti <alexghiti@...osinc.com>
Cc: linux-arch@...r.kernel.org, linux-kernel@...r.kernel.org,
Palmer Dabbelt <palmer@...osinc.com>, linux-riscv@...ts.infradead.org,
linux-arm-kernel@...ts.infradead.org, linuxppc-dev@...ts.ozlabs.org,
linux-mm@...ck.org, loongarch@...ts.linux.dev, linux-mips@...r.kernel.org,
linux-parisc@...r.kernel.org, linux-s390@...r.kernel.org,
linux-sh@...r.kernel.org, sparclinux@...r.kernel.org,
linux-kselftest@...r.kernel.org, Charlie Jenkins <charlie@...osinc.com>
Subject: [PATCH 10/16] arm: mm: Support MAP_BELOW_HINT
Add support for MAP_BELOW_HINT to mmap by restricting high_limit to addr
when the flag is enabled.
Signed-off-by: Charlie Jenkins <charlie@...osinc.com>
---
arch/arm/mm/mmap.c | 10 ++++++++++
1 file changed, 10 insertions(+)
diff --git a/arch/arm/mm/mmap.c b/arch/arm/mm/mmap.c
index d65d0e6ed10a..fa0c79447b78 100644
--- a/arch/arm/mm/mmap.c
+++ b/arch/arm/mm/mmap.c
@@ -71,6 +71,8 @@ arch_get_unmapped_area(struct file *filp, unsigned long addr,
info.length = len;
info.low_limit = mm->mmap_base;
info.high_limit = TASK_SIZE;
+ if (flags & MAP_BELOW_HINT)
+ info.high_limit = MIN(info.high_limit, addr + len);
info.align_mask = do_align ? (PAGE_MASK & (SHMLBA - 1)) : 0;
info.align_offset = pgoff << PAGE_SHIFT;
return vm_unmapped_area(&info);
@@ -122,6 +124,12 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
info.length = len;
info.low_limit = FIRST_USER_ADDRESS;
info.high_limit = mm->mmap_base;
+ if (flags & MAP_BELOW_HINT)
+ /*
+ * Subtract (STACK_TOP - mm->mmap_base) to get random
+ * offset defined in mmap_base() in mm/util.c
+ */
+ info.high_limit = MIN(info.high_limit, (addr + len) - (STACK_TOP - mm->mmap_base));
info.align_mask = do_align ? (PAGE_MASK & (SHMLBA - 1)) : 0;
info.align_offset = pgoff << PAGE_SHIFT;
addr = vm_unmapped_area(&info);
@@ -137,6 +145,8 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
info.flags = 0;
info.low_limit = mm->mmap_base;
info.high_limit = TASK_SIZE;
+ if (flags & MAP_BELOW_HINT)
+ info.high_limit = MIN(info.high_limit, addr + len);
addr = vm_unmapped_area(&info);
}
--
2.45.0
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