libc: Introduce calls to sysconf to get page size. #163462
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Created using spr 1.3.6-beta.1
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@llvm/pr-subscribers-libc Author: Peter Collingbourne (pcc) Changessysconf(_SC_PAGESIZE) is implemented now. Full diff: https://github.com/llvm/llvm-project/pull/163462.diff 4 Files Affected:
diff --git a/libc/test/src/sys/mman/linux/mincore_test.cpp b/libc/test/src/sys/mman/linux/mincore_test.cpp
index fb86252992def..7d470fc4b08b1 100644
--- a/libc/test/src/sys/mman/linux/mincore_test.cpp
+++ b/libc/test/src/sys/mman/linux/mincore_test.cpp
@@ -16,12 +16,13 @@
#include "test/UnitTest/ErrnoSetterMatcher.h"
#include "test/UnitTest/Test.h"
+#include <unistd.h>
+
using LIBC_NAMESPACE::testing::ErrnoSetterMatcher::Fails;
using LIBC_NAMESPACE::testing::ErrnoSetterMatcher::Succeeds;
using LlvmLibcMincoreTest = LIBC_NAMESPACE::testing::ErrnoCheckingTest;
-// TODO: Replace with sysconf call once the function is properly implemented.
-constexpr size_t PAGE_SIZE = 4096;
+const size_t PAGE_SIZE = sysconf(_SC_PAGESIZE);
TEST_F(LlvmLibcMincoreTest, UnMappedMemory) {
unsigned char vec;
diff --git a/libc/test/src/sys/mman/linux/mlock_test.cpp b/libc/test/src/sys/mman/linux/mlock_test.cpp
index f4a072ec18a31..834c513fdda0b 100644
--- a/libc/test/src/sys/mman/linux/mlock_test.cpp
+++ b/libc/test/src/sys/mman/linux/mlock_test.cpp
@@ -27,9 +27,9 @@
#include "test/UnitTest/Test.h"
#include <sys/syscall.h>
+#include <unistd.h>
-// TODO: Replace with sysconf call once the function is properly implemented.
-constexpr size_t PAGE_SIZE = 4096;
+const size_t PAGE_SIZE = sysconf(_SC_PAGESIZE);
using namespace LIBC_NAMESPACE::testing::ErrnoSetterMatcher;
using LlvmLibcMlockTest = LIBC_NAMESPACE::testing::ErrnoCheckingTest;
diff --git a/libc/test/src/sys/mman/linux/msync_test.cpp b/libc/test/src/sys/mman/linux/msync_test.cpp
index 764a67d02e3b1..e99328992800b 100644
--- a/libc/test/src/sys/mman/linux/msync_test.cpp
+++ b/libc/test/src/sys/mman/linux/msync_test.cpp
@@ -15,8 +15,9 @@
#include "test/UnitTest/ErrnoSetterMatcher.h"
#include "test/UnitTest/Test.h"
-// TODO: Replace with sysconf call once the function is properly implemented.
-constexpr size_t PAGE_SIZE = 4096;
+#include <unistd.h>
+
+const size_t PAGE_SIZE = sysconf(_SC_PAGESIZE);
using namespace LIBC_NAMESPACE::testing::ErrnoSetterMatcher;
using LlvmLibcMsyncTest = LIBC_NAMESPACE::testing::ErrnoCheckingTest;
diff --git a/libc/test/src/sys/mman/linux/remap_file_pages_test.cpp b/libc/test/src/sys/mman/linux/remap_file_pages_test.cpp
index 094bcb2c71427..f10c8d4211631 100644
--- a/libc/test/src/sys/mman/linux/remap_file_pages_test.cpp
+++ b/libc/test/src/sys/mman/linux/remap_file_pages_test.cpp
@@ -17,9 +17,9 @@
#include <sys/mman.h>
#include <sys/stat.h> // For S_IRWXU
+#include <unistd.h>
-// TODO: Replace with sysconf call once the function is properly implemented.
-constexpr size_t PAGE_SIZE = 4096;
+const size_t PAGE_SIZE = sysconf(_SC_PAGESIZE);
using LIBC_NAMESPACE::testing::ErrnoSetterMatcher::Fails;
using LIBC_NAMESPACE::testing::ErrnoSetterMatcher::Succeeds;
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| #include "test/UnitTest/ErrnoSetterMatcher.h" | ||
| #include "test/UnitTest/Test.h" | ||
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| #include <unistd.h> |
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this should be the LLVM-libc sysconf.
Suggested change
| #include <unistd.h> | |
| #include "src/unistd/sysconf.h" |
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| // TODO: Replace with sysconf call once the function is properly implemented. | ||
| constexpr size_t PAGE_SIZE = 4096; | ||
| const size_t PAGE_SIZE = sysconf(_SC_PAGESIZE); |
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you need to call the sysconf in the LLVM-libc namespace.
Suggested change
| const size_t PAGE_SIZE = sysconf(_SC_PAGESIZE); | |
| const size_t PAGE_SIZE = LIBC_NAMESPACE::sysconf(_SC_PAGESIZE); |
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It's fine for tests, but just be aware that this changes the behavior to require a global constructor.
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Right, I also figured that would be fine for tests
pcc
commented
Oct 14, 2025
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| // TODO: Replace with sysconf call once the function is properly implemented. | ||
| constexpr size_t PAGE_SIZE = 4096; | ||
| const size_t PAGE_SIZE = sysconf(_SC_PAGESIZE); |
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Right, I also figured that would be fine for tests
Created using spr 1.3.6-beta.1
pcc
commented
Oct 15, 2025
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You'll also need to update the cmake for the tests so that it gets linked properly.
Done
Please also update the bazel files.
Sorry, I'm not set up to build LLVM with Bazel and I don't think that contributors are required to update the alternative build system files.
| #include "test/UnitTest/ErrnoSetterMatcher.h" | ||
| #include "test/UnitTest/Test.h" | ||
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| #include <unistd.h> |
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| // TODO: Replace with sysconf call once the function is properly implemented. | ||
| constexpr size_t PAGE_SIZE = 4096; | ||
| const size_t PAGE_SIZE = sysconf(_SC_PAGESIZE); |
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sysconf(_SC_PAGESIZE) is implemented now.