hugetlbfs: add arch_hugetlb_valid_size

Patch series "Clean up hugetlb boot command line processing", v4.

Longpeng(Mike) reported a weird message from hugetlb command line
processing and proposed a solution [1].  While the proposed patch does
address the specific issue, there are other related issues in command line
processing.  As hugetlbfs evolved, updates to command line processing have
been made to meet immediate needs and not necessarily in a coordinated
manner.  The result is that some processing is done in arch specific code,
some is done in arch independent code and coordination is problematic.
Semantics can vary between architectures.

The patch series does the following:
- Define arch specific arch_hugetlb_valid_size routine used to validate
  passed huge page sizes.
- Move hugepagesz= command line parsing out of arch specific code and into
  an arch independent routine.
- Clean up command line processing to follow desired semantics and
  document those semantics.

[1] https://lore.kernel.org/linux-mm/[email protected]

This patch (of 3):

The architecture independent routine hugetlb_default_setup sets up the
default huge pages size.  It has no way to verify if the passed value is
valid, so it accepts it and attempts to validate at a later time.  This
requires undocumented cooperation between the arch specific and arch
independent code.

For architectures that support more than one huge page size, provide a
routine arch_hugetlb_valid_size to validate a huge page size.
hugetlb_default_setup can use this to validate passed values.

arch_hugetlb_valid_size will also be used in a subsequent patch to move
processing of the "hugepagesz=" in arch specific code to a common routine
in arch independent code.

Signed-off-by: Mike Kravetz <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Acked-by: Gerald Schaefer <[email protected]>	[s390]
Acked-by: Will Deacon <[email protected]>
Cc: Catalin Marinas <[email protected]>
Cc: Benjamin Herrenschmidt <[email protected]>
Cc: Paul Mackerras <[email protected]>
Cc: Paul Walmsley <[email protected]>
Cc: Palmer Dabbelt <[email protected]>
Cc: Albert Ou <[email protected]>
Cc: Heiko Carstens <[email protected]>
Cc: Vasily Gorbik <[email protected]>
Cc: Christian Borntraeger <[email protected]>
Cc: David S. Miller <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Dave Hansen <[email protected]>
Cc: Jonathan Corbet <[email protected]>
Cc: Longpeng <[email protected]>
Cc: Christophe Leroy <[email protected]>
Cc: Randy Dunlap <[email protected]>
Cc: Mina Almasry <[email protected]>
Cc: Peter Xu <[email protected]>
Cc: Nitesh Narayan Lal <[email protected]>
Cc: Anders Roxell <[email protected]>
Cc: "Aneesh Kumar K.V" <[email protected]>
Cc: Qian Cai <[email protected]>
Cc: Stephen Rothwell <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Link: http://lkml.kernel.org/r/[email protected]
Link: http://lkml.kernel.org/r/[email protected]
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Linus Torvalds <[email protected]>

1 files changed, 16 insertions, 8 deletions

diff --git a/arch/sparc/mm/init_64.c b/arch/sparc/mm/init_64.c
index 79d3c5e0802e..24475b73657a 100644
--- a/arch/sparc/mm/init_64.c
+++ b/arch/sparc/mm/init_64.c
@@ -360,16 +360,11 @@ static void __init pud_huge_patch(void)
 	__asm__ __volatile__("flush %0" : : "r" (addr));
 }
 
-static int __init setup_hugepagesz(char *string)
+bool __init arch_hugetlb_valid_size(unsigned long size)
 {
-	unsigned long long hugepage_size;
-	unsigned int hugepage_shift;
+	unsigned int hugepage_shift = ilog2(size);
 	unsigned short hv_pgsz_idx;
 	unsigned int hv_pgsz_mask;
-	int rc = 0;
-
-	hugepage_size = memparse(string, &string);
-	hugepage_shift = ilog2(hugepage_size);
 
 	switch (hugepage_shift) {
 	case HPAGE_16GB_SHIFT:
@@ -397,7 +392,20 @@ static int __init setup_hugepagesz(char *string)
 		hv_pgsz_mask = 0;
 	}
 
-	if ((hv_pgsz_mask & cpu_pgsz_mask) == 0U) {
+	if ((hv_pgsz_mask & cpu_pgsz_mask) == 0U)
+		return false;
+
+	return true;
+}
+
+static int __init setup_hugepagesz(char *string)
+{
+	unsigned long long hugepage_size;
+	int rc = 0;
+
+	hugepage_size = memparse(string, &string);
+
+	if (!arch_hugetlb_valid_size((unsigned long)hugepage_size)) {
 		hugetlb_bad_size();
 		pr_err("hugepagesz=%llu not supported by MMU.\n",
 			hugepage_size);