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android_bionic/libc/private/bionic_asm_tls.h

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Reorganize static TLS memory for ELF TLS For ELF TLS "local-exec" accesses, the static linker assumes that an executable's TLS segment is located at a statically-known offset from the thread pointer (i.e. "variant 1" for ARM and "variant 2" for x86). Because these layouts are incompatible, Bionic generally needs to allocate its TLS slots differently between different architectures. To allow per-architecture TLS slots: - Replace the TLS_SLOT_xxx enumerators with macros. New ARM slots are generally negative, while new x86 slots are generally positive. - Define a bionic_tcb struct that provides two things: - a void* raw_slots_storage[BIONIC_TLS_SLOTS] field - an inline accessor function: void*& tls_slot(size_t tpindex); For ELF TLS, it's necessary to allocate a temporary TCB (i.e. TLS slots), because the runtime linker doesn't know how large the static TLS area is until after it has loaded all of the initial solibs. To accommodate Golang, it's necessary to allocate the pthread keys at a fixed, small, positive offset from the thread pointer. This CL moves the pthread keys into bionic_tls, then allocates a single mapping per thread that looks like so: - stack guard - stack [omitted for main thread and with pthread_attr_setstack] - static TLS: - bionic_tcb [exec TLS will either precede or succeed the TCB] - bionic_tls [prefixed by the pthread keys] - [solib TLS segments will be placed here] - guard page As before, if the new mapping includes a stack, the pthread_internal_t is allocated on it. At startup, Bionic allocates a temporary bionic_tcb object on the stack, then allocates a temporary bionic_tls object using mmap. This mmap is delayed because the linker can't currently call async_safe_fatal() before relocating itself. Later, Bionic allocates a stack-less thread mapping for the main thread, and copies slots from the temporary TCB to the new TCB. (See *::copy_from_bootstrap methods.) Bug: http://b/78026329 Test: bionic unit tests Test: verify that a Golang app still works Test: verify that a Golang app crashes if bionic_{tls,tcb} are swapped Merged-In: I6543063752f4ec8ef6dc9c7f2a06ce2a18fc5af3 Change-Id: I6543063752f4ec8ef6dc9c7f2a06ce2a18fc5af3 (cherry picked from commit 1e660b70da625fcbf1e43dfae09b7b4817fa1660)
2019-01-03 10:51:30 +00:00
/*
* Copyright (C) 2018 The Android Open Source Project
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#pragma once
/** WARNING WARNING WARNING
**
** This header file is *NOT* part of the public Bionic ABI/API and should not
** be used/included by user-serviceable parts of the system (e.g.
** applications).
**
** It is only provided here for the benefit of Android components that need a
** pre-allocated slot for performance reasons (including ART, the OpenGL
** subsystem, and sanitizers).
**/
// Bionic TCB / TLS slots:
//
// - TLS_SLOT_SELF: On x86-{32,64}, the kernel makes TLS memory available via
// the gs/fs segments. To get the address of a TLS variable, the first slot
// of TLS memory (accessed using %gs:0 / %fs:0) holds the address of the
// gs/fs segment. This slot is used by:
// - OpenGL and compiler-rt
// - Accesses of x86 ELF TLS variables
//
// - TLS_SLOT_OPENGL and TLS_SLOT_OPENGL_API: These two aren't used by bionic
// itself, but allow the graphics code to access TLS directly rather than
// using the pthread API.
//
// - TLS_SLOT_STACK_GUARD: Used for -fstack-protector by:
// - Clang targeting Android/arm64
// - gcc targeting Linux/x86-{32,64}
//
// - TLS_SLOT_SANITIZER: Lets sanitizers avoid using pthread_getspecific for
// finding the current thread state.
//
// - TLS_SLOT_DTV: Pointer to ELF TLS dynamic thread vector.
//
// - TLS_SLOT_ART_THREAD_SELF: Fast storage for Thread::Current() in ART.
//
// - TLS_SLOT_BIONIC_TLS: Optimizes accesses to bionic_tls by one load versus
// finding it using __get_thread().
Reassign TLS slot 2 to TLS_SLOT_APP. Bug: http://b/78026329 Bug: http://b/118381796 Test: mmma bionic Change-Id: I1c50d3293206e59d54fbbfe9c9e3d6fd54dded3e
2019-01-24 02:47:10 +00:00
//
// - TLS_SLOT_APP: Available for use by apps in Android Q and later. (This slot
// was used for errno in P and earlier.)
Reorganize static TLS memory for ELF TLS For ELF TLS "local-exec" accesses, the static linker assumes that an executable's TLS segment is located at a statically-known offset from the thread pointer (i.e. "variant 1" for ARM and "variant 2" for x86). Because these layouts are incompatible, Bionic generally needs to allocate its TLS slots differently between different architectures. To allow per-architecture TLS slots: - Replace the TLS_SLOT_xxx enumerators with macros. New ARM slots are generally negative, while new x86 slots are generally positive. - Define a bionic_tcb struct that provides two things: - a void* raw_slots_storage[BIONIC_TLS_SLOTS] field - an inline accessor function: void*& tls_slot(size_t tpindex); For ELF TLS, it's necessary to allocate a temporary TCB (i.e. TLS slots), because the runtime linker doesn't know how large the static TLS area is until after it has loaded all of the initial solibs. To accommodate Golang, it's necessary to allocate the pthread keys at a fixed, small, positive offset from the thread pointer. This CL moves the pthread keys into bionic_tls, then allocates a single mapping per thread that looks like so: - stack guard - stack [omitted for main thread and with pthread_attr_setstack] - static TLS: - bionic_tcb [exec TLS will either precede or succeed the TCB] - bionic_tls [prefixed by the pthread keys] - [solib TLS segments will be placed here] - guard page As before, if the new mapping includes a stack, the pthread_internal_t is allocated on it. At startup, Bionic allocates a temporary bionic_tcb object on the stack, then allocates a temporary bionic_tls object using mmap. This mmap is delayed because the linker can't currently call async_safe_fatal() before relocating itself. Later, Bionic allocates a stack-less thread mapping for the main thread, and copies slots from the temporary TCB to the new TCB. (See *::copy_from_bootstrap methods.) Bug: http://b/78026329 Test: bionic unit tests Test: verify that a Golang app still works Test: verify that a Golang app crashes if bionic_{tls,tcb} are swapped Merged-In: I6543063752f4ec8ef6dc9c7f2a06ce2a18fc5af3 Change-Id: I6543063752f4ec8ef6dc9c7f2a06ce2a18fc5af3 (cherry picked from commit 1e660b70da625fcbf1e43dfae09b7b4817fa1660)
2019-01-03 10:51:30 +00:00
#if defined(__arm__) || defined(__aarch64__)
// The ARM ELF TLS ABI specifies[1] that the thread pointer points at a 2-word
// TCB followed by the executable's TLS segment. Both the TCB and the
// executable's segment are aligned according to the segment, so Bionic requires
// a minimum segment alignment, which effectively reserves an 8-word TCB. The
// ARM spec allocates the first TCB word to the DTV.
//
// [1] "Addenda to, and Errata in, the ABI for the ARM Architecture". Section 3.
// http://infocenter.arm.com/help/topic/com.arm.doc.ihi0045e/IHI0045E_ABI_addenda.pdf
#define MIN_TLS_SLOT -1 // update this value when reserving a slot
#define TLS_SLOT_BIONIC_TLS -1
#define TLS_SLOT_DTV 0
#define TLS_SLOT_THREAD_ID 1
Reassign TLS slot 2 to TLS_SLOT_APP. Bug: http://b/78026329 Bug: http://b/118381796 Test: mmma bionic Change-Id: I1c50d3293206e59d54fbbfe9c9e3d6fd54dded3e
2019-01-24 02:47:10 +00:00
#define TLS_SLOT_APP 2 // was historically used for errno
Reorganize static TLS memory for ELF TLS For ELF TLS "local-exec" accesses, the static linker assumes that an executable's TLS segment is located at a statically-known offset from the thread pointer (i.e. "variant 1" for ARM and "variant 2" for x86). Because these layouts are incompatible, Bionic generally needs to allocate its TLS slots differently between different architectures. To allow per-architecture TLS slots: - Replace the TLS_SLOT_xxx enumerators with macros. New ARM slots are generally negative, while new x86 slots are generally positive. - Define a bionic_tcb struct that provides two things: - a void* raw_slots_storage[BIONIC_TLS_SLOTS] field - an inline accessor function: void*& tls_slot(size_t tpindex); For ELF TLS, it's necessary to allocate a temporary TCB (i.e. TLS slots), because the runtime linker doesn't know how large the static TLS area is until after it has loaded all of the initial solibs. To accommodate Golang, it's necessary to allocate the pthread keys at a fixed, small, positive offset from the thread pointer. This CL moves the pthread keys into bionic_tls, then allocates a single mapping per thread that looks like so: - stack guard - stack [omitted for main thread and with pthread_attr_setstack] - static TLS: - bionic_tcb [exec TLS will either precede or succeed the TCB] - bionic_tls [prefixed by the pthread keys] - [solib TLS segments will be placed here] - guard page As before, if the new mapping includes a stack, the pthread_internal_t is allocated on it. At startup, Bionic allocates a temporary bionic_tcb object on the stack, then allocates a temporary bionic_tls object using mmap. This mmap is delayed because the linker can't currently call async_safe_fatal() before relocating itself. Later, Bionic allocates a stack-less thread mapping for the main thread, and copies slots from the temporary TCB to the new TCB. (See *::copy_from_bootstrap methods.) Bug: http://b/78026329 Test: bionic unit tests Test: verify that a Golang app still works Test: verify that a Golang app crashes if bionic_{tls,tcb} are swapped Merged-In: I6543063752f4ec8ef6dc9c7f2a06ce2a18fc5af3 Change-Id: I6543063752f4ec8ef6dc9c7f2a06ce2a18fc5af3 (cherry picked from commit 1e660b70da625fcbf1e43dfae09b7b4817fa1660)
2019-01-03 10:51:30 +00:00
#define TLS_SLOT_OPENGL 3
#define TLS_SLOT_OPENGL_API 4
#define TLS_SLOT_STACK_GUARD 5
#define TLS_SLOT_SANITIZER 6 // was historically used for dlerror
#define TLS_SLOT_ART_THREAD_SELF 7
// The maximum slot is fixed by the minimum TLS alignment in Bionic executables.
Remove TLS_SLOT_TSAN(8) As of the switch to clang-r346389c, it has been replaced with TLS_SLOT_SANITIZER(6). lld reserves 8 words beyond the TP on arm/arm64, so Bionic can't use anything beyond 7. The DTV and bionic_tls slots on x86 haven't been part of a release yet, and they should be strictly internal to Bionic anyway, so shift them down. Bug: http://b/78026329 Test: bionic unit tests Change-Id: Ifb3b2d8d85efe1417ee9a10b657b665ec6f2fd3d
2019-01-16 04:33:27 +00:00
#define MAX_TLS_SLOT 7
Reorganize static TLS memory for ELF TLS For ELF TLS "local-exec" accesses, the static linker assumes that an executable's TLS segment is located at a statically-known offset from the thread pointer (i.e. "variant 1" for ARM and "variant 2" for x86). Because these layouts are incompatible, Bionic generally needs to allocate its TLS slots differently between different architectures. To allow per-architecture TLS slots: - Replace the TLS_SLOT_xxx enumerators with macros. New ARM slots are generally negative, while new x86 slots are generally positive. - Define a bionic_tcb struct that provides two things: - a void* raw_slots_storage[BIONIC_TLS_SLOTS] field - an inline accessor function: void*& tls_slot(size_t tpindex); For ELF TLS, it's necessary to allocate a temporary TCB (i.e. TLS slots), because the runtime linker doesn't know how large the static TLS area is until after it has loaded all of the initial solibs. To accommodate Golang, it's necessary to allocate the pthread keys at a fixed, small, positive offset from the thread pointer. This CL moves the pthread keys into bionic_tls, then allocates a single mapping per thread that looks like so: - stack guard - stack [omitted for main thread and with pthread_attr_setstack] - static TLS: - bionic_tcb [exec TLS will either precede or succeed the TCB] - bionic_tls [prefixed by the pthread keys] - [solib TLS segments will be placed here] - guard page As before, if the new mapping includes a stack, the pthread_internal_t is allocated on it. At startup, Bionic allocates a temporary bionic_tcb object on the stack, then allocates a temporary bionic_tls object using mmap. This mmap is delayed because the linker can't currently call async_safe_fatal() before relocating itself. Later, Bionic allocates a stack-less thread mapping for the main thread, and copies slots from the temporary TCB to the new TCB. (See *::copy_from_bootstrap methods.) Bug: http://b/78026329 Test: bionic unit tests Test: verify that a Golang app still works Test: verify that a Golang app crashes if bionic_{tls,tcb} are swapped Merged-In: I6543063752f4ec8ef6dc9c7f2a06ce2a18fc5af3 Change-Id: I6543063752f4ec8ef6dc9c7f2a06ce2a18fc5af3 (cherry picked from commit 1e660b70da625fcbf1e43dfae09b7b4817fa1660)
2019-01-03 10:51:30 +00:00
#elif defined(__i386__) || defined(__x86_64__)
// x86 uses variant 2 ELF TLS layout, which places the executable's TLS segment
// immediately before the thread pointer. New slots are allocated at positive
// offsets from the thread pointer.
#define MIN_TLS_SLOT 0
#define TLS_SLOT_SELF 0
#define TLS_SLOT_THREAD_ID 1
Reassign TLS slot 2 to TLS_SLOT_APP. Bug: http://b/78026329 Bug: http://b/118381796 Test: mmma bionic Change-Id: I1c50d3293206e59d54fbbfe9c9e3d6fd54dded3e
2019-01-24 02:47:10 +00:00
#define TLS_SLOT_APP 2 // was historically used for errno
Reorganize static TLS memory for ELF TLS For ELF TLS "local-exec" accesses, the static linker assumes that an executable's TLS segment is located at a statically-known offset from the thread pointer (i.e. "variant 1" for ARM and "variant 2" for x86). Because these layouts are incompatible, Bionic generally needs to allocate its TLS slots differently between different architectures. To allow per-architecture TLS slots: - Replace the TLS_SLOT_xxx enumerators with macros. New ARM slots are generally negative, while new x86 slots are generally positive. - Define a bionic_tcb struct that provides two things: - a void* raw_slots_storage[BIONIC_TLS_SLOTS] field - an inline accessor function: void*& tls_slot(size_t tpindex); For ELF TLS, it's necessary to allocate a temporary TCB (i.e. TLS slots), because the runtime linker doesn't know how large the static TLS area is until after it has loaded all of the initial solibs. To accommodate Golang, it's necessary to allocate the pthread keys at a fixed, small, positive offset from the thread pointer. This CL moves the pthread keys into bionic_tls, then allocates a single mapping per thread that looks like so: - stack guard - stack [omitted for main thread and with pthread_attr_setstack] - static TLS: - bionic_tcb [exec TLS will either precede or succeed the TCB] - bionic_tls [prefixed by the pthread keys] - [solib TLS segments will be placed here] - guard page As before, if the new mapping includes a stack, the pthread_internal_t is allocated on it. At startup, Bionic allocates a temporary bionic_tcb object on the stack, then allocates a temporary bionic_tls object using mmap. This mmap is delayed because the linker can't currently call async_safe_fatal() before relocating itself. Later, Bionic allocates a stack-less thread mapping for the main thread, and copies slots from the temporary TCB to the new TCB. (See *::copy_from_bootstrap methods.) Bug: http://b/78026329 Test: bionic unit tests Test: verify that a Golang app still works Test: verify that a Golang app crashes if bionic_{tls,tcb} are swapped Merged-In: I6543063752f4ec8ef6dc9c7f2a06ce2a18fc5af3 Change-Id: I6543063752f4ec8ef6dc9c7f2a06ce2a18fc5af3 (cherry picked from commit 1e660b70da625fcbf1e43dfae09b7b4817fa1660)
2019-01-03 10:51:30 +00:00
#define TLS_SLOT_OPENGL 3
#define TLS_SLOT_OPENGL_API 4
#define TLS_SLOT_STACK_GUARD 5
#define TLS_SLOT_SANITIZER 6 // was historically used for dlerror
#define TLS_SLOT_ART_THREAD_SELF 7
Remove TLS_SLOT_TSAN(8) As of the switch to clang-r346389c, it has been replaced with TLS_SLOT_SANITIZER(6). lld reserves 8 words beyond the TP on arm/arm64, so Bionic can't use anything beyond 7. The DTV and bionic_tls slots on x86 haven't been part of a release yet, and they should be strictly internal to Bionic anyway, so shift them down. Bug: http://b/78026329 Test: bionic unit tests Change-Id: Ifb3b2d8d85efe1417ee9a10b657b665ec6f2fd3d
2019-01-16 04:33:27 +00:00
#define TLS_SLOT_DTV 8
#define TLS_SLOT_BIONIC_TLS 9
#define MAX_TLS_SLOT 9 // update this value when reserving a slot
Reorganize static TLS memory for ELF TLS For ELF TLS "local-exec" accesses, the static linker assumes that an executable's TLS segment is located at a statically-known offset from the thread pointer (i.e. "variant 1" for ARM and "variant 2" for x86). Because these layouts are incompatible, Bionic generally needs to allocate its TLS slots differently between different architectures. To allow per-architecture TLS slots: - Replace the TLS_SLOT_xxx enumerators with macros. New ARM slots are generally negative, while new x86 slots are generally positive. - Define a bionic_tcb struct that provides two things: - a void* raw_slots_storage[BIONIC_TLS_SLOTS] field - an inline accessor function: void*& tls_slot(size_t tpindex); For ELF TLS, it's necessary to allocate a temporary TCB (i.e. TLS slots), because the runtime linker doesn't know how large the static TLS area is until after it has loaded all of the initial solibs. To accommodate Golang, it's necessary to allocate the pthread keys at a fixed, small, positive offset from the thread pointer. This CL moves the pthread keys into bionic_tls, then allocates a single mapping per thread that looks like so: - stack guard - stack [omitted for main thread and with pthread_attr_setstack] - static TLS: - bionic_tcb [exec TLS will either precede or succeed the TCB] - bionic_tls [prefixed by the pthread keys] - [solib TLS segments will be placed here] - guard page As before, if the new mapping includes a stack, the pthread_internal_t is allocated on it. At startup, Bionic allocates a temporary bionic_tcb object on the stack, then allocates a temporary bionic_tls object using mmap. This mmap is delayed because the linker can't currently call async_safe_fatal() before relocating itself. Later, Bionic allocates a stack-less thread mapping for the main thread, and copies slots from the temporary TCB to the new TCB. (See *::copy_from_bootstrap methods.) Bug: http://b/78026329 Test: bionic unit tests Test: verify that a Golang app still works Test: verify that a Golang app crashes if bionic_{tls,tcb} are swapped Merged-In: I6543063752f4ec8ef6dc9c7f2a06ce2a18fc5af3 Change-Id: I6543063752f4ec8ef6dc9c7f2a06ce2a18fc5af3 (cherry picked from commit 1e660b70da625fcbf1e43dfae09b7b4817fa1660)
2019-01-03 10:51:30 +00:00
#endif
#define BIONIC_TLS_SLOTS (MAX_TLS_SLOT - MIN_TLS_SLOT + 1)