cosmopolitan/libc/runtime/stack.h
Justine Tunney ec2cb88058 Make fixes and improvements
- Document more compiler flags
- Expose new __print_maps() api
- Better overflow checking in mmap()
- Improve the shell example somewhat
- Fix minor runtime bugs regarding stacks
- Make kill() on fork()+execve()'d children work
- Support CLONE_CHILD_CLEARTID for proper joining
- Fix recent possible deadlock regression with --ftrace
2022-05-19 16:57:49 -07:00

111 lines
3.8 KiB
C

#ifndef COSMOPOLITAN_LIBC_RUNTIME_STACK_H_
#define COSMOPOLITAN_LIBC_RUNTIME_STACK_H_
#include "ape/config.h"
#include "libc/dce.h"
#include "libc/nt/version.h"
#include "libc/runtime/runtime.h"
#if !(__ASSEMBLER__ + __LINKER__ + 0)
/**
* Tunes APE stack maximum size.
*
* This defaults to `STACKSIZE`. The bottom-most page will be protected
* to ensure your stack does not magically grow beyond this value. It's
* possible to detect stack overflows, by calling `ShowCrashReports()`.
* Your stack size must be a power of two; the linker will check this.
*
* If you want to know how much stack your programs needs, then
*
* STATIC_YOINK("stack_usage_logging");
*
* will install an atexit() handler that appends to `o/$MODE/stack.log`
*
* @see libc/sysv/systemfive.S
* @see ape/ape.lds
*/
#define STATIC_STACK_SIZE(BYTES) \
STATIC_SYMBOL("ape_stack_memsz", _STACK_STRINGIFY(BYTES) _STACK_EXTRA)
/**
* Tunes APE stack virtual address.
*
* This value must be aligned according to your stack size, and that's
* checked by your linker script. This defaults to `0x700000000000` so
*
* 1. It's easy to see how close you are to the bottom
* 2. The linker script error is unlikely to happen
*
* This macro will be respected, with two exceptions
*
* 1. In MODE=tiny the operating system provided stack is used instead
* 2. Windows 7 doesn't support 64-bit addresses, so we'll instead use
* `0x10000000 - GetStackSize()` as the stack address
*
* @see libc/sysv/systemfive.S
* @see libc/nt/winmain.greg.c
* @see ape/ape.lds
*/
#define STATIC_STACK_ADDR(ADDR) \
STATIC_SYMBOL("ape_stack_vaddr", _STACK_STRINGIFY(ADDR))
#define _STACK_STRINGIFY(ADDR) #ADDR
#if IsAsan()
#define _STACK_EXTRA "*2"
#else
#define _STACK_EXTRA ""
#endif
#if defined(__GNUC__) && defined(__ELF__) && !defined(__STRICT_ANSI__)
COSMOPOLITAN_C_START_
extern char ape_stack_prot[] __attribute__((__weak__));
extern char ape_stack_memsz[] __attribute__((__weak__));
extern char ape_stack_align[] __attribute__((__weak__));
/**
* Returns size of stack, which is always a two power.
*/
#define GetStackSize() ((uintptr_t)ape_stack_memsz)
/**
* Returns address of bottom of stack.
*
* This takes into consideration threads and sigaltstack. This is
* implemented as a fast pure expression, since we're able to make the
* assumption that stack sizes are two powers and aligned. This is
* thanks to (1) the linker script checks the statically chosen sizes,
* and (2) the mmap() address picker will choose aligned addresses when
* the provided size is a two power.
*/
#define GetStackAddr(ADDEND) \
((void *)((((intptr_t)__builtin_frame_address(0) - 1) & -GetStackSize()) + \
(ADDEND)))
/**
* Returns preferred bottom address of stack.
*
* This is the stakc address of the main process. The only time that
* isn't guaranteed to be the case is in MODE=tiny, since it doesn't
* link the code for stack creation at startup. This generally isn't
* problematic, since MODE=tiny doesn't use any of the runtime codes
* which want the stack to be cheaply knowable, e.g. ftrace, kprintf
*/
#define GetStaticStackAddr(ADDEND) \
({ \
intptr_t vAddr; \
if (!IsWindows() || IsAtLeastWindows10()) { \
__asm__(".weak\tape_stack_vaddr\n\t" \
"movabs\t%1+ape_stack_vaddr,%0" \
: "=r"(vAddr) \
: "i"(ADDEND)); \
} else { \
vAddr = 0x10000000; \
} \
(void *)vAddr; \
})
COSMOPOLITAN_C_END_
#endif /* GNU ELF */
#endif /* !(__ASSEMBLER__ + __LINKER__ + 0) */
#endif /* COSMOPOLITAN_LIBC_RUNTIME_STACK_H_ */