Re: [PATCH -next v2] arm64: fix build warning for ARM64_MEMSTART_SHIFT
From: zhangjianhua (E)
Date: Tue Jul 25 2023 - 08:03:51 EST
在 2023/7/25 18:15, Catalin Marinas 写道:
On Tue, Jul 25, 2023 at 04:47:46PM +0800, zhangjianhua (E) wrote:
在 2023/7/25 12:22, Anshuman Khandual 写道:
On 7/24/23 20:41, Catalin Marinas wrote:
On Mon, Jul 24, 2023 at 05:27:51PM +0000, Zhang Jianhua wrote:
When building with W=1, the following warning occurs.
arch/arm64/include/asm/kernel-pgtable.h:129:41: error: "PUD_SHIFT" is not defined, evaluates to 0 [-Werror=undef]
129 | #define ARM64_MEMSTART_SHIFT PUD_SHIFT
| ^~~~~~~~~
arch/arm64/include/asm/kernel-pgtable.h:142:5: note: in expansion of macro ‘ARM64_MEMSTART_SHIFT’
142 | #if ARM64_MEMSTART_SHIFT < SECTION_SIZE_BITS
| ^~~~~~~~~~~~~~~~~~~~
Another thing that's missing here is that the warning is probably when
this file is included from asm-offests.h or some .S file.
diff --git a/arch/arm64/include/asm/kernel-pgtable.h b/arch/arm64/include/asm/kernel-pgtable.h
index 577773870b66..51bdce66885d 100644
--- a/arch/arm64/include/asm/kernel-pgtable.h
+++ b/arch/arm64/include/asm/kernel-pgtable.h
@@ -125,12 +125,14 @@
* (64k granule), or a multiple that can be mapped using contiguous bits
* in the page tables: 32 * PMD_SIZE (16k granule)
*/
-#if defined(CONFIG_ARM64_4K_PAGES)
+#if defined(CONFIG_ARM64_4K_PAGES) && defined(PUD_SHIFT)
#define ARM64_MEMSTART_SHIFT PUD_SHIFT
That's not the correct fix since PUD_SHIFT should always be defined.
When CONFIG_PGTABLE_LEVELS == 3, pgtable-types.h includes
asm-generic/pgtable-nopud.h and this defines PUD_SHIFT. We either got
Right, PUD_SHIFT is always defined irrespective of page table levels.
ARM64_MEMSTART_SHIFT defined in the wrong file or kernel-pgtable.h does
not pull the relevant headers (either directly or via an included
header). Even if kernel-pgtable.h ends up including the nopud/nopmd
headers, P*D_SHIFT is guarded by an #indef __ASSEMBLY__ in those files.
Something like below appears to fix this, though I'm not particularly
fond of guarding the ARM64_MEMSTART_* definitions by #ifndef
__ASSEMBLY__ for no apparent reason (could add a comment though):
-----------------------8<---------------------------
diff --git a/arch/arm64/include/asm/kernel-pgtable.h b/arch/arm64/include/asm/kernel-pgtable.h
index 577773870b66..fcea7e87a6ca 100644
--- a/arch/arm64/include/asm/kernel-pgtable.h
+++ b/arch/arm64/include/asm/kernel-pgtable.h
@@ -118,6 +118,8 @@
#define SWAPPER_RX_MMUFLAGS (SWAPPER_RW_MMUFLAGS | PTE_RDONLY)
#endif
+#ifndef __ASSEMBLY__
+
/*
* To make optimal use of block mappings when laying out the linear
* mapping, round down the base of physical memory to a size that can
@@ -145,4 +147,6 @@
#define ARM64_MEMSTART_ALIGN (1UL << ARM64_MEMSTART_SHIFT)
#endif
+#endif /* __ASSEMBLY__ */
+
#endif /* __ASM_KERNEL_PGTABLE_H */
diff --git a/arch/arm64/include/asm/pgtable-hwdef.h b/arch/arm64/include/asm/pgtable-hwdef.h
index e4944d517c99..22b36f2d5d93 100644
--- a/arch/arm64/include/asm/pgtable-hwdef.h
+++ b/arch/arm64/include/asm/pgtable-hwdef.h
@@ -6,6 +6,7 @@
#define __ASM_PGTABLE_HWDEF_H
#include <asm/memory.h>
+#include <asm/pgtable-types.h>
/*
* Number of page-table levels required to address 'va_bits' wide
diff --git a/arch/arm64/include/asm/pgtable-types.h b/arch/arm64/include/asm/pgtable-types.h
index b8f158ae2527..ae86e66fdb11 100644
--- a/arch/arm64/include/asm/pgtable-types.h
+++ b/arch/arm64/include/asm/pgtable-types.h
@@ -11,6 +11,8 @@
#include <asm/types.h>
+#ifndef __ASSEMBLY__
+
typedef u64 pteval_t;
typedef u64 pmdval_t;
typedef u64 pudval_t;
@@ -44,6 +46,8 @@ typedef struct { pteval_t pgprot; } pgprot_t;
#define pgprot_val(x) ((x).pgprot)
#define __pgprot(x) ((pgprot_t) { (x) } )
+#endif /* __ASSEMBLY__ */
+
#if CONFIG_PGTABLE_LEVELS == 2
#include <asm-generic/pgtable-nopmd.h>
#elif CONFIG_PGTABLE_LEVELS == 3
-----------------------8<---------------------------
To avoid guarding the ARM64_MEMSTART_* definitions, we could instead
move the P*D_SHIFT definitions in asm-generic/pgtable-nop*d.h outside
the #ifndef __ASSEMBLY__ block.
OR could ARM64_MEMSTART_SHIFT and ARM64_MEMSTART_ALIGN computation blocks
be moved inside arch/arm64/mm/init.c, where it is used exclusively. Seems
to be solving the problem as well.
That's fine by me, better than adding the #ifndef __ASSEMBLY__ around
them.
This method can avoid the current compilation warning, but does not
solve the problem that PUD_SHIFT and PMD_SHIFT undefined in fact, and
it is contrary to XXX_SHIFT should always be defined. Maybe it would
be more appropriate to solve this issue directly.
For .c files, we can solve this by including asm/pgtable-types.h in
asm/pgtable-hwdef.h. This still leaves P*D_SHIFT undefined for .S files
since the generic nop*d.h headers guard the shifts with !__ASSEMBLY__
but do we really care about this? I haven't seen any other warning of
P*D_SHIFT not being defined. If you do want to solve these, just go and
change the generic headers to take the shift out of the asm guard. I
don't think it's worth it.
OK, agree, I will send a new patch for Anshuman's method.