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freebsd-dev/sys/ia64/include/ucontext.h

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This is the first snapshot of the FreeBSD/ia64 kernel. This kernel will not work on any real hardware (or fully work on any simulator). Much more needs to happen before this is actually functional but its nice to see the FreeBSD copyright message appear in the ia64 simulator.
2000-09-29 13:46:07 +00:00
/*-
Use get_mcontext() to construct the signal context in sendsig() and use set_mcontext() to restore the context in sigreturn(). Since we put the syscall number and the syscall arguments in the trapframe (we don't save the scratch registers for syscalls, which allows us to reuse the space to our advantage), create a MD specific flag so that we save the scratch registers even for syscalls. We would not be able to restart a syscall otherwise. The signal trampoline does not need to flush the regiters anymore, because get_mcontext() already handles that. In fact, if we set up the context correctly, we do not need to have a trampoline at all. This change however only minimally changes the trampoline code. In follow-up commits this can be further optimized. Note that normally we preserve cfm and iip in the trapframe created by the EPC syscall path when we restore a context in set_mcontext() because those fields are not normally set for a synchronuous context. The kernel puts the return address and frame info of the syscall stub in there. By preserving these fields we hide this detail from userland which allows us to use setcontext(2) for user created contexts. However, sigreturn() is commonly called from the trampoline, which means that if we preserve cfm and iip in all cases, we would return to the trampoline after the sigreturn(), which means we hit the safety net: we call exit(2). So, we do not preserve cfm and iip when we have a synchronous context that also has scratch registers (the uncommon context created by sendsig() only), under the assumption that if such a context is created in userland, something special is going on and the use of cfm and iip is then just another quirk. All this is invisible in the common case.
2003-11-09 22:17:36 +00:00
* Copyright (c) 1999, 2003 Marcel Moolenaar
This is the first snapshot of the FreeBSD/ia64 kernel. This kernel will not work on any real hardware (or fully work on any simulator). Much more needs to happen before this is actually functional but its nice to see the FreeBSD copyright message appear in the ia64 simulator.
2000-09-29 13:46:07 +00:00
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer
* in this position and unchanged.
* 2. 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.
* 3. The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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.
*
* $FreeBSD$
*/
#ifndef _MACHINE_UCONTEXT_H_
#define _MACHINE_UCONTEXT_H_
Revamp of the syscall path, exception and context handling. The prime objectives are: o Implement a syscall path based on the epc inststruction (see sys/ia64/ia64/syscall.s). o Revisit the places were we need to save and restore registers and define those contexts in terms of the register sets (see sys/ia64/include/_regset.h). Secundairy objectives: o Remove the requirement to use contigmalloc for kernel stacks. o Better handling of the high FP registers for SMP systems. o Switch to the new cpu_switch() and cpu_throw() semantics. o Add a good unwinder to reconstruct contexts for the rare cases we need to (see sys/contrib/ia64/libuwx) Many files are affected by this change. Functionally it boils down to: o The EPC syscall doesn't preserve registers it does not need to preserve and places the arguments differently on the stack. This affects libc and truss. o The address of the kernel page directory (kptdir) had to be unstaticized for use by the nested TLB fault handler. The name has been changed to ia64_kptdir to avoid conflicts. The renaming affects libkvm. o The trapframe only contains the special registers and the scratch registers. For syscalls using the EPC syscall path no scratch registers are saved. This affects all places where the trapframe is accessed. Most notably the unaligned access handler, the signal delivery code and the debugger. o Context switching only partly saves the special registers and the preserved registers. This affects cpu_switch() and triggered the move to the new semantics, which additionally affects cpu_throw(). o The high FP registers are either in the PCB or on some CPU. context switching for them is done lazily. This affects trap(). o The mcontext has room for all registers, but not all of them have to be defined in all cases. This mostly affects signal delivery code now. The *context syscalls are as of yet still unimplemented. Many details went into the removal of the requirement to use contigmalloc for kernel stacks. The details are mostly CPU specific and limited to exception_save() and exception_restore(). The few places where we create, destroy or switch stacks were mostly simplified by not having to construct physical addresses and additionally saving the virtual addresses for later use. Besides more efficient context saving and restoring, which of course yields a noticable speedup, this also fixes the dreaded SMP bootup problem as a side-effect. The details of which are still not fully understood. This change includes all the necessary backward compatibility code to have it handle older userland binaries that use the break instruction for syscalls. Support for break-based syscalls has been pessimized in favor of a clean implementation. Due to the overall better performance of the kernel, this will still be notived as an improvement if it's noticed at all. Approved by: re@ (jhb)
2003-05-16 21:26:42 +00:00
#include <machine/_regset.h>
This is the first snapshot of the FreeBSD/ia64 kernel. This kernel will not work on any real hardware (or fully work on any simulator). Much more needs to happen before this is actually functional but its nice to see the FreeBSD copyright message appear in the ia64 simulator.
2000-09-29 13:46:07 +00:00
Better define the flags in the mcontext_t and properly set the flags when we create contexts. The meaning of the flags are documented in <machine/ucontext.h>. I only list them here to help browsing the commit logs: _MC_FLAGS_ASYNC_CONTEXT _MC_FLAGS_HIGHFP_VALID _MC_FLAGS_KSE_SET_MBOX _MC_FLAGS_RETURN_VALID _MC_FLAGS_SCRATCH_VALID Yes, _MC_FLAGS_KSE_SET_MBOX is a hack and I'm proud of it :-)
2003-08-07 07:52:39 +00:00
/*
* The mc_flags field provides the necessary clues when dealing with the gory
* details of ia64 specific contexts. A comprehensive explanation is added for
* everybody's sanity, including the author's.
*
* The first and foremost variation in the context is synchronous contexts
* (= synctx) versus asynchronous contexts (= asynctx). A synctx is created
* synchronously WRT program execution and has the advantage that none of the
* scratch registers have to be saved. They are assumed to be clobbered by the
* call to the function that creates the context. An asynctx needs to have the
* scratch registers preserved because it can describe any point in a thread's
* (or process') execution.
Simplify the contexts created by the kernel and remove the related flags. We now create asynchronous contexts or syscall contexts only. Syscall contexts differ from the minimal ABI dictated contexts by having the scratch registers saved and restored because that's where we keep the syscall arguments and syscall return values. Since this change affects KSE, have it use kse_switchin(2) for the "new" syscall context.
2003-12-07 20:47:33 +00:00
* The second variation is for synchronous contexts. When the kernel creates
* a synchronous context if needs to preserve the scratch registers, because
* the syscall argument and return values are stored there in the trapframe
* and they need to be preserved in order to restart a syscall or return the
* proper return values. Also, the IIP and CFM fields need to be preserved
* as they point to the syscall stub, which the kernel saves as a favor to
* userland (it keeps the stubs small and simple).
Better define the flags in the mcontext_t and properly set the flags when we create contexts. The meaning of the flags are documented in <machine/ucontext.h>. I only list them here to help browsing the commit logs: _MC_FLAGS_ASYNC_CONTEXT _MC_FLAGS_HIGHFP_VALID _MC_FLAGS_KSE_SET_MBOX _MC_FLAGS_RETURN_VALID _MC_FLAGS_SCRATCH_VALID Yes, _MC_FLAGS_KSE_SET_MBOX is a hack and I'm proud of it :-)
2003-08-07 07:52:39 +00:00
*
* Below a description of the flags and their meaning:
*
* _MC_FLAGS_ASYNC_CONTEXT
* If set, indicates that mc_scratch and mc_scratch_fp are both
Simplify the contexts created by the kernel and remove the related flags. We now create asynchronous contexts or syscall contexts only. Syscall contexts differ from the minimal ABI dictated contexts by having the scratch registers saved and restored because that's where we keep the syscall arguments and syscall return values. Since this change affects KSE, have it use kse_switchin(2) for the "new" syscall context.
2003-12-07 20:47:33 +00:00
* valid. IFF not set, _MC_FLAGS_SYSCALL_CONTEXT indicates if the
* synchronous context is one corresponding to a syscall or not.
* Only the kernel is expected to create such a context and it's
* probably wise to let the kernel restore it.
Better define the flags in the mcontext_t and properly set the flags when we create contexts. The meaning of the flags are documented in <machine/ucontext.h>. I only list them here to help browsing the commit logs: _MC_FLAGS_ASYNC_CONTEXT _MC_FLAGS_HIGHFP_VALID _MC_FLAGS_KSE_SET_MBOX _MC_FLAGS_RETURN_VALID _MC_FLAGS_SCRATCH_VALID Yes, _MC_FLAGS_KSE_SET_MBOX is a hack and I'm proud of it :-)
2003-08-07 07:52:39 +00:00
* _MC_FLAGS_HIGHFP_VALID
* If set, indicates that the high FP registers (f32-f127) are
* valid. This flag is very likely not going to be set for any
* sensible synctx, but is not explicitly disallowed. Any synctx
* that has this flag may or may not have the high FP registers
* restored. In short: don't do it.
Simplify the contexts created by the kernel and remove the related flags. We now create asynchronous contexts or syscall contexts only. Syscall contexts differ from the minimal ABI dictated contexts by having the scratch registers saved and restored because that's where we keep the syscall arguments and syscall return values. Since this change affects KSE, have it use kse_switchin(2) for the "new" syscall context.
2003-12-07 20:47:33 +00:00
* _MC_FLAGS_SYSCALL_CONTEXT
* If set (hence _MC_FLAGS_ASYNC_CONTEXT is not set) indicates
* that the scratch registers contain syscall arguments and
* return values and that additionally IIP and CFM are valid.
* Only the kernel is expected to create such a context. It's
* probably wise to let the kernel restore it.
Better define the flags in the mcontext_t and properly set the flags when we create contexts. The meaning of the flags are documented in <machine/ucontext.h>. I only list them here to help browsing the commit logs: _MC_FLAGS_ASYNC_CONTEXT _MC_FLAGS_HIGHFP_VALID _MC_FLAGS_KSE_SET_MBOX _MC_FLAGS_RETURN_VALID _MC_FLAGS_SCRATCH_VALID Yes, _MC_FLAGS_KSE_SET_MBOX is a hack and I'm proud of it :-)
2003-08-07 07:52:39 +00:00
*/
This is the first snapshot of the FreeBSD/ia64 kernel. This kernel will not work on any real hardware (or fully work on any simulator). Much more needs to happen before this is actually functional but its nice to see the FreeBSD copyright message appear in the ia64 simulator.
2000-09-29 13:46:07 +00:00
typedef struct __mcontext {
Don't use uint64_t. Use unsigned long instead. One is supposed to use ucontext_t without having to include headers other than <ucontext.h>.
2003-08-02 01:12:31 +00:00
unsigned long mc_flags;
Better define the flags in the mcontext_t and properly set the flags when we create contexts. The meaning of the flags are documented in <machine/ucontext.h>. I only list them here to help browsing the commit logs: _MC_FLAGS_ASYNC_CONTEXT _MC_FLAGS_HIGHFP_VALID _MC_FLAGS_KSE_SET_MBOX _MC_FLAGS_RETURN_VALID _MC_FLAGS_SCRATCH_VALID Yes, _MC_FLAGS_KSE_SET_MBOX is a hack and I'm proud of it :-)
2003-08-07 07:52:39 +00:00
#define _MC_FLAGS_ASYNC_CONTEXT 0x0001
#define _MC_FLAGS_HIGHFP_VALID 0x0002
Simplify the contexts created by the kernel and remove the related flags. We now create asynchronous contexts or syscall contexts only. Syscall contexts differ from the minimal ABI dictated contexts by having the scratch registers saved and restored because that's where we keep the syscall arguments and syscall return values. Since this change affects KSE, have it use kse_switchin(2) for the "new" syscall context.
2003-12-07 20:47:33 +00:00
#define _MC_FLAGS_SYSCALL_CONTEXT 0x0008
Don't use uint64_t. Use unsigned long instead. One is supposed to use ucontext_t without having to include headers other than <ucontext.h>.
2003-08-02 01:12:31 +00:00
unsigned long _reserved_;
Revamp of the syscall path, exception and context handling. The prime objectives are: o Implement a syscall path based on the epc inststruction (see sys/ia64/ia64/syscall.s). o Revisit the places were we need to save and restore registers and define those contexts in terms of the register sets (see sys/ia64/include/_regset.h). Secundairy objectives: o Remove the requirement to use contigmalloc for kernel stacks. o Better handling of the high FP registers for SMP systems. o Switch to the new cpu_switch() and cpu_throw() semantics. o Add a good unwinder to reconstruct contexts for the rare cases we need to (see sys/contrib/ia64/libuwx) Many files are affected by this change. Functionally it boils down to: o The EPC syscall doesn't preserve registers it does not need to preserve and places the arguments differently on the stack. This affects libc and truss. o The address of the kernel page directory (kptdir) had to be unstaticized for use by the nested TLB fault handler. The name has been changed to ia64_kptdir to avoid conflicts. The renaming affects libkvm. o The trapframe only contains the special registers and the scratch registers. For syscalls using the EPC syscall path no scratch registers are saved. This affects all places where the trapframe is accessed. Most notably the unaligned access handler, the signal delivery code and the debugger. o Context switching only partly saves the special registers and the preserved registers. This affects cpu_switch() and triggered the move to the new semantics, which additionally affects cpu_throw(). o The high FP registers are either in the PCB or on some CPU. context switching for them is done lazily. This affects trap(). o The mcontext has room for all registers, but not all of them have to be defined in all cases. This mostly affects signal delivery code now. The *context syscalls are as of yet still unimplemented. Many details went into the removal of the requirement to use contigmalloc for kernel stacks. The details are mostly CPU specific and limited to exception_save() and exception_restore(). The few places where we create, destroy or switch stacks were mostly simplified by not having to construct physical addresses and additionally saving the virtual addresses for later use. Besides more efficient context saving and restoring, which of course yields a noticable speedup, this also fixes the dreaded SMP bootup problem as a side-effect. The details of which are still not fully understood. This change includes all the necessary backward compatibility code to have it handle older userland binaries that use the break instruction for syscalls. Support for break-based syscalls has been pessimized in favor of a clean implementation. Due to the overall better performance of the kernel, this will still be notived as an improvement if it's noticed at all. Approved by: re@ (jhb)
2003-05-16 21:26:42 +00:00
struct _special mc_special;
struct _callee_saved mc_preserved;
struct _callee_saved_fp mc_preserved_fp;
struct _caller_saved mc_scratch;
struct _caller_saved_fp mc_scratch_fp;
struct _high_fp mc_high_fp;
This is the first snapshot of the FreeBSD/ia64 kernel. This kernel will not work on any real hardware (or fully work on any simulator). Much more needs to happen before this is actually functional but its nice to see the FreeBSD copyright message appear in the ia64 simulator.
2000-09-29 13:46:07 +00:00
} mcontext_t;
#endif /* !_MACHINE_UCONTEXT_H_ */
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