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bionic: libdl_cfi: Remove PAGE_SIZE usage

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Use max_page_size() for build time variable alignments instead
of PAGE_SIZE.

In the 4k targets there is no functional difference since
max_page_size() == page_size() == 4096.

On a 16kb device max_page_size() == 65536 and page_size() == 16384.
However, aligning up does not incur any memory regressions
since the .bss/.data sections are still be backed in PAGE_SIZE'ed
chunks. See: go/16k-page-aligned-variables

Bug: 296275298
Test: mma
Change-Id: Ic944235d8a5742a51a8fb0f2a0b75e532f404110
Signed-off-by: Kalesh Singh <kaleshsingh@google.com>
This commit is contained in:
Kalesh Singh 2023-08-24 23:36:30 -07:00
parent 0398f8ab3a
commit 461c64db9e
1 changed files with 3 additions and 3 deletions
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6
libdl/libdl_cfi.cpp
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@ -26,15 +26,15 @@ __attribute__((__weak__, visibility("default"))) extern "C" void __loader_cfi_fa
// dlopen/dlclose.
static struct {
uintptr_t v;
char padding[PAGE_SIZE - sizeof(v)];
} shadow_base_storage alignas(PAGE_SIZE);
char padding[max_page_size() - sizeof(v)];
} shadow_base_storage alignas(max_page_size());
// __cfi_init is called by the loader as soon as the shadow is mapped. This may happen very early
// during startup, before libdl.so global constructors, and, on i386, even before __libc_sysinfo is
// initialized. This function should not do any system calls.
extern "C" uintptr_t* __cfi_init(uintptr_t shadow_base) {
shadow_base_storage.v = shadow_base;
static_assert(sizeof(shadow_base_storage) == PAGE_SIZE, "");
static_assert(sizeof(shadow_base_storage) == max_page_size(), "");
return &shadow_base_storage.v;
}