powerpc/64s/radix: Enable huge vmalloc mappings

mainline inclusion
from mainline-5.13-rc1
commit 8abddd96
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I3ZGKZ
CVE: NA

-------------------------------------------------

This reduces TLB misses by nearly 30x on a `git diff` workload on a
2-node POWER9 (59,800 -> 2,100) and reduces CPU cycles by 0.54%, due
to vfs hashes being allocated with 2MB pages.
Signed-off-by: NNicholas Piggin <npiggin@gmail.com>
Reviewed-by: NChristophe Leroy <christophe.leroy@csgroup.eu>
Acked-by: NMichael Ellerman <mpe@ellerman.id.au>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210503091755.613393-1-npiggin@gmail.com
Conflicts:
	arch/powerpc/kernel/module.c
Signed-off-by: NChen Wandun <chenwandun@huawei.com>
Reviewed-by: NTong Tiangen <tongtiangen@huawei.com>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>

Documentation/admin-guide/kernel-parameters.txt

@@ -3274,6 +3274,8 @@
 
 	nohugeiomap	[KNL,X86,PPC,ARM64] Disable kernel huge I/O mappings.
 
+	nohugevmalloc	[PPC] Disable kernel huge vmalloc mappings.
+
 	nosmt		[KNL,S390] Disable symmetric multithreading (SMT).
 			Equivalent to smt=1.
 

arch/powerpc/Kconfig

@@ -179,6 +179,7 @@ config PPC
 	select GENERIC_TIME_VSYSCALL
 	select HAVE_ARCH_AUDITSYSCALL
 	select HAVE_ARCH_HUGE_VMAP		if PPC_BOOK3S_64 && PPC_RADIX_MMU
+	select HAVE_ARCH_HUGE_VMALLOC		if HAVE_ARCH_HUGE_VMAP
 	select HAVE_ARCH_JUMP_LABEL
 	select HAVE_ARCH_KASAN			if PPC32 && PPC_PAGE_SHIFT <= 14
 	select HAVE_ARCH_KASAN_VMALLOC		if PPC32 && PPC_PAGE_SHIFT <= 14

arch/powerpc/kernel/module.c

@@ -8,6 +8,7 @@
 #include <linux/moduleloader.h>
 #include <linux/err.h>
 #include <linux/vmalloc.h>
+#include <linux/mm.h>
 #include <linux/bug.h>
 #include <asm/module.h>
 #include <linux/uaccess.h>
@@ -87,13 +88,36 @@ int module_finalize(const Elf_Ehdr *hdr,
 	return 0;
 }
 
-#ifdef MODULES_VADDR
+static __always_inline void *
+__module_alloc(unsigned long size, unsigned long start, unsigned long end)
+{
+	/*
+	 * Don't do huge page allocations for modules yet until more testing
+	 * is done. STRICT_MODULE_RWX may require extra work to support this
+	 * too.
+	 */
+	return __vmalloc_node_range(size, 1, start, end, GFP_KERNEL, PAGE_KERNEL_EXEC,
+				    VM_FLUSH_RESET_PERMS | VM_NO_HUGE_VMAP,
+				    NUMA_NO_NODE, __builtin_return_address(0));
+}
+
 void *module_alloc(unsigned long size)
 {
+#ifdef MODULES_VADDR
+	unsigned long limit = (unsigned long)_etext - SZ_32M;
+	void *ptr = NULL;
+
 	BUILD_BUG_ON(TASK_SIZE > MODULES_VADDR);
 
-	return __vmalloc_node_range(size, 1, MODULES_VADDR, MODULES_END, GFP_KERNEL,
-				    PAGE_KERNEL_EXEC, VM_FLUSH_RESET_PERMS, NUMA_NO_NODE,
-				    __builtin_return_address(0));
-}
+	/* First try within 32M limit from _etext to avoid branch trampolines */
+	if (MODULES_VADDR < PAGE_OFFSET && MODULES_END > limit)
+		ptr = __module_alloc(size, limit, MODULES_END);
+
+	if (!ptr)
+		ptr = __module_alloc(size, MODULES_VADDR, MODULES_END);
+
+	return ptr;
+#else
+	return __module_alloc(size, VMALLOC_START, VMALLOC_END);
 #endif
+}