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Message-Id: <20240827-patches-below_hint_mmap-v1-8-46ff2eb9022d@rivosinc.com>
Date: Tue, 27 Aug 2024 22:49:14 -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 08/16] x86: 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/x86/kernel/sys_x86_64.c | 25 ++++++++++++++++++++++---
1 file changed, 22 insertions(+), 3 deletions(-)
diff --git a/arch/x86/kernel/sys_x86_64.c b/arch/x86/kernel/sys_x86_64.c
index 01d7cd85ef97..fa16b38f3702 100644
--- a/arch/x86/kernel/sys_x86_64.c
+++ b/arch/x86/kernel/sys_x86_64.c
@@ -86,7 +86,7 @@ SYSCALL_DEFINE6(mmap, unsigned long, addr, unsigned long, len,
return ksys_mmap_pgoff(addr, len, prot, flags, fd, off >> PAGE_SHIFT);
}
-static void find_start_end(unsigned long addr, unsigned long flags,
+static void find_start_end(unsigned long addr, unsigned long len, unsigned long flags,
unsigned long *begin, unsigned long *end)
{
if (!in_32bit_syscall() && (flags & MAP_32BIT)) {
@@ -106,10 +106,14 @@ static void find_start_end(unsigned long addr, unsigned long flags,
}
*begin = get_mmap_base(1);
+
if (in_32bit_syscall())
*end = task_size_32bit();
else
*end = task_size_64bit(addr > DEFAULT_MAP_WINDOW);
+
+ if (flags & MAP_BELOW_HINT)
+ *end = MIN(*end, addr + len);
}
static inline unsigned long stack_guard_placement(vm_flags_t vm_flags)
@@ -132,7 +136,7 @@ arch_get_unmapped_area_vmflags(struct file *filp, unsigned long addr, unsigned l
if (flags & MAP_FIXED)
return addr;
- find_start_end(addr, flags, &begin, &end);
+ find_start_end(addr, len, flags, &begin, &end);
if (len > end)
return -ENOMEM;
@@ -166,6 +170,7 @@ arch_get_unmapped_area_topdown_vmflags(struct file *filp, unsigned long addr0,
struct mm_struct *mm = current->mm;
unsigned long addr = addr0;
struct vm_unmapped_area_info info = {};
+ unsigned long task_size, mmap_base;
/* requested length too big for entire address space */
if (len > TASK_SIZE)
@@ -198,7 +203,8 @@ arch_get_unmapped_area_topdown_vmflags(struct file *filp, unsigned long addr0,
else
info.low_limit = PAGE_SIZE;
- info.high_limit = get_mmap_base(0);
+ mmap_base = get_mmap_base(0);
+ info.high_limit = mmap_base;
info.start_gap = stack_guard_placement(vm_flags);
/*
@@ -210,6 +216,19 @@ arch_get_unmapped_area_topdown_vmflags(struct file *filp, unsigned long addr0,
*/
if (addr > DEFAULT_MAP_WINDOW && !in_32bit_syscall())
info.high_limit += TASK_SIZE_MAX - DEFAULT_MAP_WINDOW;
+ if (flags & MAP_BELOW_HINT) {
+#ifdef CONFIG_HAVE_ARCH_COMPAT_MMAP_BASES
+ task_size = task_size_32bit();
+#else
+ task_size = task_size_64bit(0);
+#endif
+ /*
+ * mmap_base is defined by PAGE_ALIGN(task_size - gap - rnd) so
+ * subtract out the task_size to isolate the gap + rnd.
+ */
+ info.high_limit = MIN(info.high_limit,
+ (addr + len) - (task_size - mmap_base));
+ }
info.align_offset = pgoff << PAGE_SHIFT;
if (filp) {
--
2.45.0
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