Merge "libc: Provide ucontext_t/mcontext_t/<sys/ucontext.h>"

2 files changed, 251 insertions, 0 deletions

diff --git a/libc/arch-x86/include/machine/signal.h b/libc/arch-x86/include/machine/signal.h
new file mode 100644
index 0000000..ba3fe37
--- /dev/null
+++ b/libc/arch-x86/include/machine/signal.h
@@ -0,0 +1,67 @@
+/*
+ * Copyright (C) 2012 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.
+ */
+#ifndef _ARCH_X86_MACHINE_SIGNAL_H_
+#define _ARCH_X86_MACHINE_SIGNAL_H_
+
+#include <stddef.h>
+#include <sys/types.h>
+#include <sys/cdefs.h>
+
+__BEGIN_DECLS
+
+#include <asm/signal.h>
+#include <asm/sigcontext.h>
+
+#ifdef _ASM_GENERIC_SIGINFO_H
+#error "You cannot include <asm/siginfo.h> before <signal.h>!"
+#endif
+#define __ARCH_SI_UID_T __kernel_uid32_t
+#include <asm/siginfo.h>
+#undef __ARCH_SI_UID_T
+
+#include <stdint.h>
+
+/* See comment in arch-arm/include/machine/signal.h.
+ * The x86 kernel also uses 64-bit signal masks while defining sigset-t
+ * as a 32-bit type.
+ */
+typedef unsigned long __kernel_sigset_t[2];
+
+/* _NSIG is used by the SIGRTMAX definition under <asm/signal.h>, however
+ * its definition is part of a #if __KERNEL__ .. #endif block in the original
+ * kernel headers and is thus not part of our cleaned-up versions.
+ *
+ * Looking at the current kernel sources, it is defined as 64 for x86.
+ */
+#ifndef _NSIG
+#  define _NSIG  64
+#endif
+
+__END_DECLS
+
+#endif /* _ARCH_X86_MACHINE_SIGNAL_H_ */
diff --git a/libc/arch-x86/include/machine/ucontext.h b/libc/arch-x86/include/machine/ucontext.h
new file mode 100644
index 0000000..da226c9
--- /dev/null
+++ b/libc/arch-x86/include/machine/ucontext.h
@@ -0,0 +1,184 @@
+/*
+ * Copyright (C) 2012 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.
+ */
+#ifndef _ARCH_X86_SYS_UCONTEXT_H_
+#define _ARCH_X86_SYS_UCONTEXT_H_
+
+#include <signal.h>
+#include <stdint.h>
+
+__BEGIN_DECLS
+
+/* Technical note:
+ *
+ * On x86, there are differences in the way GLibc and the Linux kernel declare
+ * ucontext_t. Here are the details (they differ from ARM significantly):
+ *
+ *  - The kernel implements 'uc_mcontext' with a 'struct sigcontext',
+ *    while GLibc defines 'mcontext_t' in a binary-compatible way
+ *    (same size, same binary layout), but with different field naming/access
+ *    conventions.
+ *
+ *    The biggest difference is that 'struct sigcontext' requires named fields
+ *    like "eax", or "ebp" to access the state of register values, while GLibc
+ *    provides an array (gregs[]) of 32-bit values, that can be accessed
+ *    through indexing, plus some enum/macros like REG_EAX or REG_ESP to get
+ *    to specific register values.
+ *
+ *    For maximum portability of existing client code, this header follows
+ *    the GLibc convention. Client code, and the C library, should never
+ *    try to include <asm/ucontext.h>
+ *
+ *  - The floating-point state is not stored in the mcontext_t. For historical
+ *    reasons, the 'fpregs' field of 'mcontext_t' is really a pointer to a
+ *    different block of memory. More specifically:
+ *
+ *    * When passed to a signal handler, the pointer points to some memory
+ *      on the signal stack, populated by the kernel before calling the
+ *      handler in user space.
+ *
+ *    * In GLibc's getcontext()/setcontext() implementation, the pointer will
+ *      point to the ucontext_t structure (more specifically the __fpregs_mem
+ *      field after uc_sigmask).
+ *
+ *    * Note that in both cases, the pointer can be NULL if no floating-point
+ *      operation has been performed on the current thread yet.
+ *
+ * - The 'struct _libc_fpstate' structure declared by GLibc corresponds to
+ *   both the FP state managed by getcontext()/setcontext(), and the start
+ *   of the FP state stored by the kernel and passed to a signal handler.
+ *
+ *   This matches the data saved by the FNSTENV IA-32 instruction.
+ *
+ *   IMPORTANT: GLibc does not save the MMX/SSE state, i.e. it does not use
+ *              FXSAVE / FXRSTOR instructions in *context() functions.
+ *
+ *   It is used by client code to retrieve the state of the FPU registers
+ *   (e.g. Google Breakpad does that).
+ *
+ *  Reference source files:
+ *    $KERNEL/arch/x86/include/asm/sigcontext_32.h
+ *    $KERNEL/arch/x86/include/asm/sigcontext.h
+ *    $KERNEL/arch/x86/include/asm/ucontext.h
+ *
+ *    $GLIBC/sysdeps/unix/sysv/linux/i386/getcontext.S
+ *    $GLIBC/sysdeps/unix/sysv/linux/i386/setcontext.S
+ *    $GLIBC/sysdeps/unix/sysv/linux/x86/sys/ucontext.h
+ */
+
+/* First, the kernel-compatible version, for reference. */
+typedef struct __kernel_ucontext {
+  unsigned long              uc_flags;
+  struct __kernel_ucontext*  uc_link;
+  stack_t                    uc_stack;
+  struct sigcontext          uc_mcontext;
+  __kernel_sigset_t          uc_sigmask;
+} __kernel_ucontext_t;
+
+/* Second, the GLibc-compatible version */
+
+#define NGREG   19
+typedef int     greg_t;
+typedef greg_t  gregset_t[NGREG];
+
+enum {
+  REG_GS = 0, REG_FS, REG_ES, REG_DS,
+  REG_EDI, REG_ESI, REG_EBP, REG_ESP,
+  REG_EBX, REG_EDX, REG_ECX, REG_EAX,
+  REG_TRAPNO, REG_ERR, REG_EIP, REG_CS,
+  REG_EFL, REG_UESP, REG_SS
+};
+
+/* GLibc defines both macros and enums. Probably to let client do
+ *  #ifdef REG_XXXX ... #endif. Do the same here. */
+#define REG_GS     REG_GS
+#define REG_FS     REG_FS
+#define REG_ES     REG_ES
+#define REG_DS     REG_DS
+
+#define REG_EDI    REG_EDI
+#define REG_ESI    REG_ESI
+#define REG_EBP    REG_EBP
+#define REG_ESP    REG_ESP
+
+#define REG_EBX    REG_EBX
+#define REG_EDX    REG_EDX
+#define REG_ECX    REG_ECX
+#define REG_EAX    REG_EAX
+
+#define REG_TRAPNO REG_TRAPNO
+#define REG_ERR    REG_ERR
+#define REG_EIP    REG_EIP
+#define REG_CS     REG_CS
+#define REG_EFL    REG_EFL
+#define REG_UESP   REG_UESP
+#define REG_SS     REG_SS
+
+/* 80-bit floating-point register */
+struct _libc_fpreg {
+  unsigned short significand[4];
+  unsigned short exponent;
+};
+
+/* Simple floating-point state, see FNSTENV instruction */
+struct _libc_fpstate {
+  unsigned long cw;
+  unsigned long sw;
+  unsigned long tag;
+  unsigned long ipoff;
+  unsigned long cssel;
+  unsigned long dataoff;
+  unsigned long datasel;
+  struct _libc_fpreg _st[8];
+  unsigned long status;
+};
+
+typedef struct _libc_fpstate* fpregset_t;
+
+typedef struct {
+  gregset_t   gregs;
+  fpregset_t  fpregs;   /* Really a pointer to _libc_fpstate! */
+} mcontext_t;
+
+typedef struct ucontext {
+  uint32_t          uc_flags;
+  struct ucontext*  uc_link;
+  stack_t           uc_stack;
+  mcontext_t        uc_mcontext;
+  /* Only expose the 32 non-realtime signals in Bionic's 32-bit sigset_t
+   * The _unused field is required padding from the kernel. */
+  sigset_t          uc_sigmask;
+  char _unused[sizeof(__kernel_sigset_t) - sizeof(sigset_t)];
+  /* Storage area for *context() functions only - private, don't use. */
+  struct _libc_fpstate __fpregs_mem;
+  /* Growth opportunity - in case we want to save MMX/SSE stuff there too */
+  int _unused2[128 - sizeof(struct _libc_fpstate)/sizeof(int)];
+} ucontext_t;
+
+__END_DECLS
+
+#endif /* _ARCH_X86_SYS_UCONTEXT_H_ */