LinuxLists.cc - [PATCH 2/5] mm: Introduce pudp/p4dp/pgdp

2023-10-02 15:20:53

Subject: [PATCH 2/5] mm: Introduce pudp/p4dp/pgdp_get() functions

Instead of directly dereferencing page tables entries, which can cause
issues (see commit 20a004e7b017 ("arm64: mm: Use READ_ONCE/WRITE_ONCE when
accessing page tables"), let's introduce new functions to get the
pud/p4d/pgd entries (the pte and pmd versions already exist).

Those new functions will be used in subsequent commits by the riscv
architecture.

Signed-off-by: Alexandre Ghiti <[email protected]>
---
include/linux/pgtable.h | 21 +++++++++++++++++++++
1 file changed, 21 insertions(+)

diff --git a/include/linux/pgtable.h b/include/linux/pgtable.h
index 1fba072b3dac..4ce68bcc201d 100644
--- a/include/linux/pgtable.h
+++ b/include/linux/pgtable.h
@@ -284,6 +284,27 @@ static inline pmd_t pmdp_get(pmd_t *pmdp)
}
#endif

+#ifndef pudp_get
+static inline pud_t pudp_get(pud_t *pudp)
+{
+ return READ_ONCE(*pudp);
+}
+#endif
+
+#ifndef p4dp_get
+static inline p4d_t p4dp_get(p4d_t *p4dp)
+{
+ return READ_ONCE(*p4dp);
+}
+#endif
+
+#ifndef pgdp_get
+static inline pgd_t pgdp_get(pgd_t *pgdp)
+{
+ return READ_ONCE(*pgdp);
+}
+#endif
+
#ifndef __HAVE_ARCH_PTEP_TEST_AND_CLEAR_YOUNG
static inline int ptep_test_and_clear_young(struct vm_area_struct *vma,
unsigned long address,
--
2.39.2

2023-10-03 06:27:10

by kernel test robot

[permalink] [raw]

Subject: Re: [PATCH 2/5] mm: Introduce pudp/p4dp/pgdp_get() functions

2023-10-03 07:53:47

by kernel test robot

[permalink] [raw]

Subject: Re: [PATCH 2/5] mm: Introduce pudp/p4dp/pgdp_get() functions

Hi Alexandre,

kernel test robot noticed the following build errors:

[auto build test ERROR on linus/master]
[also build test ERROR on v6.6-rc4 next-20231003]
[cannot apply to efi/next]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url: https://github.com/intel-lab-lkp/linux/commits/Alexandre-Ghiti/riscv-Use-WRITE_ONCE-when-setting-page-table-entries/20231002-231725
base: linus/master
patch link: https://lore.kernel.org/r/20231002151031.110551-3-alexghiti%40rivosinc.com
patch subject: [PATCH 2/5] mm: Introduce pudp/p4dp/pgdp_get() functions
config: arm-moxart_defconfig (https://download.01.org/0day-ci/archive/20231003/[email protected]/config)
compiler: clang version 17.0.0 (https://github.com/llvm/llvm-project.git 4a5ac14ee968ff0ad5d2cc1ffa0299048db4c88a)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20231003/[email protected]/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <[email protected]>
| Closes: https://lore.kernel.org/oe-kbuild-all/[email protected]/

All errors (new ones prefixed by >>):

In file included from arch/arm/kernel/asm-offsets.c:12:
In file included from include/linux/mm.h:29:
>> include/linux/pgtable.h:310:29: error: function cannot return array type 'pgd_t' (aka 'unsigned int[2]')
310 | static inline pgd_t pgdp_get(pgd_t *pgdp)
| ^
>> include/linux/pgtable.h:312:9: error: incompatible pointer to integer conversion returning 'const volatile pmdval_t *' (aka 'const volatile unsigned int *') from a function with result type 'int' [-Wint-conversion]
312 | return READ_ONCE(*pgdp);
| ^~~~~~~~~~~~~~~~
include/asm-generic/rwonce.h:47:28: note: expanded from macro 'READ_ONCE'
47 | #define READ_ONCE(x) \
| ^
48 | ({ \
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
49 | compiletime_assert_rwonce_type(x); \
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
50 | __READ_ONCE(x); \
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
51 | })
| ~~
In file included from arch/arm/kernel/asm-offsets.c:12:
In file included from include/linux/mm.h:1075:
In file included from include/linux/huge_mm.h:8:
In file included from include/linux/fs.h:33:
In file included from include/linux/percpu-rwsem.h:7:
In file included from include/linux/rcuwait.h:6:
In file included from include/linux/sched/signal.h:6:
include/linux/signal.h:97:11: warning: array index 3 is past the end of the array (that has type 'unsigned long[2]') [-Warray-bounds]
97 | return (set->sig[3] | set->sig[2] |
| ^ ~
arch/arm/include/asm/signal.h:17:2: note: array 'sig' declared here
17 | unsigned long sig[_NSIG_WORDS];
| ^
In file included from arch/arm/kernel/asm-offsets.c:12:
In file included from include/linux/mm.h:1075:
In file included from include/linux/huge_mm.h:8:
In file included from include/linux/fs.h:33:
In file included from include/linux/percpu-rwsem.h:7:
In file included from include/linux/rcuwait.h:6:
In file included from include/linux/sched/signal.h:6:
include/linux/signal.h:97:25: warning: array index 2 is past the end of the array (that has type 'unsigned long[2]') [-Warray-bounds]
97 | return (set->sig[3] | set->sig[2] |
| ^ ~
arch/arm/include/asm/signal.h:17:2: note: array 'sig' declared here
17 | unsigned long sig[_NSIG_WORDS];
| ^
In file included from arch/arm/kernel/asm-offsets.c:12:
In file included from include/linux/mm.h:1075:
In file included from include/linux/huge_mm.h:8:
In file included from include/linux/fs.h:33:
In file included from include/linux/percpu-rwsem.h:7:
In file included from include/linux/rcuwait.h:6:
In file included from include/linux/sched/signal.h:6:
include/linux/signal.h:113:11: warning: array index 3 is past the end of the array (that has type 'const unsigned long[2]') [-Warray-bounds]
113 | return (set1->sig[3] == set2->sig[3]) &&
| ^ ~
arch/arm/include/asm/signal.h:17:2: note: array 'sig' declared here
17 | unsigned long sig[_NSIG_WORDS];
| ^
In file included from arch/arm/kernel/asm-offsets.c:12:
In file included from include/linux/mm.h:1075:
In file included from include/linux/huge_mm.h:8:
In file included from include/linux/fs.h:33:
In file included from include/linux/percpu-rwsem.h:7:
In file included from include/linux/rcuwait.h:6:
In file included from include/linux/sched/signal.h:6:
include/linux/signal.h:113:27: warning: array index 3 is past the end of the array (that has type 'const unsigned long[2]') [-Warray-bounds]
113 | return (set1->sig[3] == set2->sig[3]) &&
| ^ ~
arch/arm/include/asm/signal.h:17:2: note: array 'sig' declared here
17 | unsigned long sig[_NSIG_WORDS];
| ^
In file included from arch/arm/kernel/asm-offsets.c:12:
In file included from include/linux/mm.h:1075:
In file included from include/linux/huge_mm.h:8:
In file included from include/linux/fs.h:33:
In file included from include/linux/percpu-rwsem.h:7:
In file included from include/linux/rcuwait.h:6:
In file included from include/linux/sched/signal.h:6:
include/linux/signal.h:114:5: warning: array index 2 is past the end of the array (that has type 'const unsigned long[2]') [-Warray-bounds]
114 | (set1->sig[2] == set2->sig[2]) &&
| ^ ~
arch/arm/include/asm/signal.h:17:2: note: array 'sig' declared here
17 | unsigned long sig[_NSIG_WORDS];
| ^
In file included from arch/arm/kernel/asm-offsets.c:12:
In file included from include/linux/mm.h:1075:
In file included from include/linux/huge_mm.h:8:
In file included from include/linux/fs.h:33:
In file included from include/linux/percpu-rwsem.h:7:
In file included from include/linux/rcuwait.h:6:
In file included from include/linux/sched/signal.h:6:
include/linux/signal.h:114:21: warning: array index 2 is past the end of the array (that has type 'const unsigned long[2]') [-Warray-bounds]
114 | (set1->sig[2] == set2->sig[2]) &&
| ^ ~
arch/arm/include/asm/signal.h:17:2: note: array 'sig' declared here
17 | unsigned long sig[_NSIG_WORDS];
| ^
In file included from arch/arm/kernel/asm-offsets.c:12:
In file included from include/linux/mm.h:1075:
In file included from include/linux/huge_mm.h:8:
In file included from include/linux/fs.h:33:
In file included from include/linux/percpu-rwsem.h:7:
In file included from include/linux/rcuwait.h:6:
In file included from include/linux/sched/signal.h:6:
include/linux/signal.h:156:1: warning: array index 3 is past the end of the array (that has type 'const unsigned long[2]') [-Warray-bounds]
156 | _SIG_SET_BINOP(sigorsets, _sig_or)

vim +310 include/linux/pgtable.h

308
309 #ifndef pgdp_get
> 310 static inline pgd_t pgdp_get(pgd_t *pgdp)
311 {
> 312 return READ_ONCE(*pgdp);
313 }
314 #endif
315

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