niansa-misc/glibc
1
0
Fork 0
mirror of git://sourceware.org/git/glibc.git synced 2025-03-06 20:58:33 +01:00
Code Issues Projects Releases Packages Wiki Activity
glibc/sysdeps/unix/sysv/linux/powerpc/sysdep.h
Adhemerval Zanella 461cab1de7 linux: Add support for getrandom vDSO 
Linux 6.11 has getrandom() in vDSO. It operates on a thread-local opaque
state allocated with mmap using flags specified by the vDSO.

Multiple states are allocated at once, as many as fit into a page, and
these are held in an array of available states to be doled out to each
thread upon first use, and recycled when a thread terminates. As these
states run low, more are allocated.

To make this procedure async-signal-safe, a simple guard is used in the
LSB of the opaque state address, falling back to the syscall if there's
reentrancy contention.

Also, _Fork() is handled by blocking signals on opaque state allocation
(so _Fork() always sees a consistent state even if it interrupts a
getrandom() call) and by iterating over the thread stack cache on
reclaim_stack. Each opaque state will be in the free states list
(grnd_alloc.states) or allocated to a running thread.

The cancellation is handled by always using GRND_NONBLOCK flags while
calling the vDSO, and falling back to the cancellable syscall if the
kernel returns EAGAIN (would block). Since getrandom is not defined by
POSIX and cancellation is supported as an extension, the cancellation is
handled as 'may occur' instead of 'shall occur' [1], meaning that if
vDSO does not block (the expected behavior) getrandom will not act as a
cancellation entrypoint. It avoids a pthread_testcancel call on the fast
path (different than 'shall occur' functions, like sem_wait()).

It is currently enabled for x86_64, which is available in Linux 6.11,
and aarch64, powerpc32, powerpc64, loongarch64, and s390x, which are
available in Linux 6.12.

Link: https://pubs.opengroup.org/onlinepubs/9799919799/nframe.html [1]
Co-developed-by: Jason A. Donenfeld <Jason@zx2c4.com>
Tested-by: Jason A. Donenfeld <Jason@zx2c4.com> # x86_64
Tested-by: Adhemerval Zanella <adhemerval.zanella@linaro.org> # x86_64, aarch64
Tested-by: Xi Ruoyao <xry111@xry111.site> # x86_64, aarch64, loongarch64
Tested-by: Stefan Liebler <stli@linux.ibm.com> # s390x
2024-11-12 14:42:12 -03:00

228 lines
8.2 KiB
C
Raw Blame History

/* Syscall definitions, Linux PowerPC generic version.
Copyright (C) 2019-2024 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<http://www.gnu.org/licenses/>. */
#ifndef _LINUX_POWERPC_SYSDEP_H
#define _LINUX_POWERPC_SYSDEP_H 1
#include <sysdeps/unix/sysv/linux/sysdep.h>
#include <sysdeps/unix/powerpc/sysdep.h>
#include <tls.h>
/* Define __set_errno() for INLINE_SYSCALL macro below. */
#include <errno.h>
/* For Linux we can use the system call table in the header file
/usr/include/asm/unistd.h
of the kernel. But these symbols do not follow the SYS_* syntax
so we have to redefine the `SYS_ify' macro here. */
#undef SYS_ify
#define SYS_ify(syscall_name) __NR_##syscall_name
/* Define a macro which expands inline into the wrapper code for a system
call. This use is for internal calls that do not need to handle errors
normally. It will never touch errno. This returns just what the kernel
gave back in the non-error (CR0.SO cleared) case, otherwise (CR0.SO set)
the negation of the return value in the kernel gets reverted. */
#define INTERNAL_VSYSCALL_CALL_TYPE(funcptr, type, nr, args...) \
({ \
register void *r0 __asm__ ("r0"); \
register long int r3 __asm__ ("r3"); \
register long int r4 __asm__ ("r4"); \
register long int r5 __asm__ ("r5"); \
register long int r6 __asm__ ("r6"); \
register long int r7 __asm__ ("r7"); \
register long int r8 __asm__ ("r8"); \
register type rval __asm__ ("r3"); \
LOADARGS_##nr (funcptr, args); \
__asm__ __volatile__ \
("mtctr %0\n\t" \
"bctrl\n\t" \
"mfcr %0\n\t" \
"0:" \
: "+r" (r0), "+r" (r3), "+r" (r4), "+r" (r5), "+r" (r6), \
"+r" (r7), "+r" (r8) \
: : "r9", "r10", "r11", "r12", \
"cr0", "cr1", "cr5", "cr6", "cr7", \
"xer", "lr", "ctr", "memory"); \
__asm__ __volatile__ ("" : "=r" (rval) : "r" (r3)); \
(long int) r0 & (1 << 28) ? -rval : rval; \
})
#define INTERNAL_VSYSCALL_CALL(funcptr, nr, args...) \
INTERNAL_VSYSCALL_CALL_TYPE(funcptr, long int, nr, args)
#define DECLARE_REGS \
register long int r0 __asm__ ("r0"); \
register long int r3 __asm__ ("r3"); \
register long int r4 __asm__ ("r4"); \
register long int r5 __asm__ ("r5"); \
register long int r6 __asm__ ("r6"); \
register long int r7 __asm__ ("r7"); \
register long int r8 __asm__ ("r8");
#define SYSCALL_SCV(nr) \
({ \
__asm__ __volatile__ \
(".machine \"push\"\n\t" \
".machine \"power9\"\n\t" \
"scv 0\n\t" \
".machine \"pop\"\n\t" \
"0:" \
: "=&r" (r0), \
"=&r" (r3), "=&r" (r4), "=&r" (r5), \
"=&r" (r6), "=&r" (r7), "=&r" (r8) \
: ASM_INPUT_##nr \
: "r9", "r10", "r11", "r12", \
"cr0", "cr1", "cr5", "cr6", "cr7", \
"xer", "lr", "ctr", "memory"); \
r3; \
})
#define SYSCALL_SC(nr) \
({ \
__asm__ __volatile__ \
("sc\n\t" \
"mfcr %0\n\t" \
"0:" \
: "=&r" (r0), \
"=&r" (r3), "=&r" (r4), "=&r" (r5), \
"=&r" (r6), "=&r" (r7), "=&r" (r8) \
: ASM_INPUT_##nr \
: "r9", "r10", "r11", "r12", \
"xer", "cr0", "ctr", "memory"); \
r0 & (1 << 28) ? -r3 : r3; \
})
/* This will only be non-empty for 64-bit systems, see below. */
#define TRY_SYSCALL_SCV(nr)
#if defined(__PPC64__) || defined(__powerpc64__)
# define SYSCALL_ARG_SIZE 8
/* For the static case, unlike the dynamic loader, there is no compile-time way
to check if we are inside startup code. So we need to check if the thread
pointer has already been setup before trying to access the TLS. */
# ifndef SHARED
# define CHECK_THREAD_POINTER (__thread_register != 0)
# else
# define CHECK_THREAD_POINTER (1)
# endif
/* When inside the dynamic loader, the thread pointer may not have been
initialized yet, so don't check for scv support in that case. */
# if defined(USE_PPC_SCV) && !IS_IN(rtld)
# undef TRY_SYSCALL_SCV
# define TRY_SYSCALL_SCV(nr) \
CHECK_THREAD_POINTER && THREAD_GET_HWCAP() & PPC_FEATURE2_SCV ? \
SYSCALL_SCV(nr) :
# endif
#else
# define SYSCALL_ARG_SIZE 4
#endif
# define INTERNAL_SYSCALL_NCS(name, nr, args...) \
({ \
DECLARE_REGS; \
LOADARGS_##nr (name, ##args); \
TRY_SYSCALL_SCV(nr) \
SYSCALL_SC(nr); \
})
#undef INTERNAL_SYSCALL
#define INTERNAL_SYSCALL(name, nr, args...) \
INTERNAL_SYSCALL_NCS (__NR_##name, nr, args)
#define LOADARGS_0(name, dummy) \
r0 = name
#define LOADARGS_1(name, __arg1) \
long int _arg1 = (long int) (__arg1); \
LOADARGS_0(name, 0); \
extern void __illegally_sized_syscall_arg1 (void); \
if (__builtin_classify_type (__arg1) != 5 \
&& sizeof (__arg1) > SYSCALL_ARG_SIZE) \
__illegally_sized_syscall_arg1 (); \
r3 = _arg1
#define LOADARGS_2(name, __arg1, __arg2) \
long int _arg2 = (long int) (__arg2); \
LOADARGS_1(name, __arg1); \
extern void __illegally_sized_syscall_arg2 (void); \
if (__builtin_classify_type (__arg2) != 5 \
&& sizeof (__arg2) > SYSCALL_ARG_SIZE) \
__illegally_sized_syscall_arg2 (); \
r4 = _arg2
#define LOADARGS_3(name, __arg1, __arg2, __arg3) \
long int _arg3 = (long int) (__arg3); \
LOADARGS_2(name, __arg1, __arg2); \
extern void __illegally_sized_syscall_arg3 (void); \
if (__builtin_classify_type (__arg3) != 5 \
&& sizeof (__arg3) > SYSCALL_ARG_SIZE) \
__illegally_sized_syscall_arg3 (); \
r5 = _arg3
#define LOADARGS_4(name, __arg1, __arg2, __arg3, __arg4) \
long int _arg4 = (long int) (__arg4); \
LOADARGS_3(name, __arg1, __arg2, __arg3); \
extern void __illegally_sized_syscall_arg4 (void); \
if (__builtin_classify_type (__arg4) != 5 \
&& sizeof (__arg4) > SYSCALL_ARG_SIZE) \
__illegally_sized_syscall_arg4 (); \
r6 = _arg4
#define LOADARGS_5(name, __arg1, __arg2, __arg3, __arg4, __arg5) \
long int _arg5 = (long int) (__arg5); \
LOADARGS_4(name, __arg1, __arg2, __arg3, __arg4); \
extern void __illegally_sized_syscall_arg5 (void); \
if (__builtin_classify_type (__arg5) != 5 \
&& sizeof (__arg5) > SYSCALL_ARG_SIZE) \
__illegally_sized_syscall_arg5 (); \
r7 = _arg5
#define LOADARGS_6(name, __arg1, __arg2, __arg3, __arg4, __arg5, __arg6) \
long int _arg6 = (long int) (__arg6); \
LOADARGS_5(name, __arg1, __arg2, __arg3, __arg4, __arg5); \
extern void __illegally_sized_syscall_arg6 (void); \
if (__builtin_classify_type (__arg6) != 5 \
&& sizeof (__arg6) > SYSCALL_ARG_SIZE) \
__illegally_sized_syscall_arg6 (); \
r8 = _arg6
#define ASM_INPUT_0 "0" (r0)
#define ASM_INPUT_1 ASM_INPUT_0, "1" (r3)
#define ASM_INPUT_2 ASM_INPUT_1, "2" (r4)
#define ASM_INPUT_3 ASM_INPUT_2, "3" (r5)
#define ASM_INPUT_4 ASM_INPUT_3, "4" (r6)
#define ASM_INPUT_5 ASM_INPUT_4, "5" (r7)
#define ASM_INPUT_6 ASM_INPUT_5, "6" (r8)
/* List of system calls which are supported as vsyscalls. */
#define VDSO_NAME "LINUX_2.6.15"
#define VDSO_HASH 123718565
#if defined(__PPC64__) || defined(__powerpc64__)
#define HAVE_CLOCK_GETRES64_VSYSCALL "__kernel_clock_getres"
#define HAVE_CLOCK_GETTIME64_VSYSCALL "__kernel_clock_gettime"
#define HAVE_CLONE3_WRAPPER 1
#else
#define HAVE_CLOCK_GETRES_VSYSCALL "__kernel_clock_getres"
#define HAVE_CLOCK_GETTIME_VSYSCALL "__kernel_clock_gettime"
#endif
#define HAVE_GETCPU_VSYSCALL "__kernel_getcpu"
#define HAVE_TIME_VSYSCALL "__kernel_time"
#define HAVE_GETTIMEOFDAY_VSYSCALL "__kernel_gettimeofday"
#define HAVE_GET_TBFREQ "__kernel_get_tbfreq"
#define HAVE_GETRANDOM_VSYSCALL "__kernel_getrandom"
#endif /* _LINUX_POWERPC_SYSDEP_H */
Reference in a new issue View git blame Copy permalink