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ANDROID: init: ensure initcall ordering with LTO

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With LTO, LLVM sorts initcalls in a single translation unit alphabetically
based on the name of the function (or actually, the variable stored in
the initcall section). Use __COUNTER__ in the variable name in an attempt
to preserve the intended order.

In addition, LTO requires all initcall variables to have unique names. Use
__LINE__ in the name to reduce the chance of name collisions.

Bug: 62093296
Bug: 67506682
Bug: 133186739
Change-Id: I4fa3cb93cba967a1440ac53328eb6b8ac649ff36
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
This commit is contained in:
Sami Tolvanen
2017-12-08 15:49:24 -08:00
committed by Alistair Strachan
parent acd5c72821
commit 9730a6289c
1 changed files with 16 additions and 2 deletions
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18
include/linux/init.h
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@@ -167,6 +167,20 @@ extern bool initcall_debug;
#ifndef __ASSEMBLY__
#ifdef CONFIG_LTO_CLANG
/*
* Use __COUNTER__ prefix in the variable to help ensure ordering
* inside a compilation unit that defines multiple initcalls, and
* __LINE__ to help prevent naming collisions.
*/
#define ___initcall_name2(c, l, fn, id) __initcall_##c##_##l##_##fn##id
#define ___initcall_name1(c, l, fn, id) ___initcall_name2(c, l, fn, id)
#define __initcall_name(fn, id) \
___initcall_name1(__COUNTER__, __LINE__, fn, id)
#else
#define __initcall_name(fn, id) __initcall_##fn##id
#endif
/*
* initcalls are now grouped by functionality into separate
* subsections. Ordering inside the subsections is determined
@@ -187,12 +201,12 @@ extern bool initcall_debug;
#define ___define_initcall(fn, id, __sec) \
__ADDRESSABLE(fn) \
asm(".section \"" #__sec ".init\", \"a\" \n" \
"__initcall_" #fn #id ": \n" \
__stringify(__initcall_name(fn, id)) ": \n" \
".long " #fn " - . \n" \
".previous \n");
#else
#define ___define_initcall(fn, id, __sec) \
static initcall_t __initcall_##fn##id __used \
static initcall_t __initcall_name(fn, id) __used \
__attribute__((__section__(#__sec ".init"))) = fn;
#endif