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Better define the flags in the mcontext_t and properly set the flags

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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 :-)
This commit is contained in:
marcel 2003-08-07 07:52:39 +00:00
parent 54a8f3fd25
commit a43546505d
2 changed files with 121 additions and 35 deletions
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102
sys/ia64/ia64/machdep.c
View File

@ -886,8 +886,9 @@ sendsig(sig_t catcher, int sig, sigset_t *mask, u_long code)
mc = &sf.sf_uc.uc_mcontext;
mc->mc_special = tf->tf_special;
mc->mc_scratch = tf->tf_scratch;
if ((tf->tf_flags & FRAME_SYSCALL) == 0) {
mc->mc_flags |= IA64_MC_FLAGS_SCRATCH_VALID;
mc->mc_flags |= _MC_FLAGS_ASYNC_CONTEXT;
mc->mc_scratch_fp = tf->tf_scratch_fp;
/*
* XXX High FP. If the process has never used the high FP,
@ -896,7 +897,9 @@ sendsig(sig_t catcher, int sig, sigset_t *mask, u_long code)
* already there (ie get them from the CPU that has them)
* and write them in the context.
*/
}
} else
mc->mc_flags |= _MC_FLAGS_SCRATCH_VALID;
save_callee_saved(&mc->mc_preserved);
save_callee_saved_fp(&mc->mc_preserved_fp);
@ -992,22 +995,29 @@ sigreturn(struct thread *td,
return (EFAULT);
/*
* XXX make sure ndirty in the current trapframe is less than
* 0x1f8 so that if we throw away the current register stack,
* we have reached the bottom of the kernel register stack.
* See also exec_setregs.
*/
/*
* Restore the user-supplied information
* Restore the user-supplied information.
* XXX Very much incomplete.
*/
mc = &uc.uc_mcontext;
tf->tf_special = mc->mc_special;
tf->tf_scratch = mc->mc_scratch;
if ((mc->mc_flags & IA64_MC_FLAGS_SCRATCH_VALID) != 0) {
if (mc->mc_flags & _MC_FLAGS_ASYNC_CONTEXT) {
tf->tf_scratch = mc->mc_scratch;
tf->tf_scratch_fp = mc->mc_scratch_fp;
/* XXX high FP. */
} else {
if ((mc->mc_flags & _MC_FLAGS_SCRATCH_VALID) == 0) {
tf->tf_scratch.gr15 = 0;
if (mc->mc_flags & _MC_FLAGS_RETURN_VALID) {
tf->tf_scratch.gr8 = mc->mc_scratch.gr8;
tf->tf_scratch.gr9 = mc->mc_scratch.gr9;
tf->tf_scratch.gr10 = mc->mc_scratch.gr10;
tf->tf_scratch.gr11 = mc->mc_scratch.gr11;
}
} else
tf->tf_scratch = mc->mc_scratch;
}
restore_callee_saved(&mc->mc_preserved);
restore_callee_saved_fp(&mc->mc_preserved_fp);
@ -1043,10 +1053,8 @@ get_mcontext(struct thread *td, mcontext_t *mc, int clear_ret)
uint64_t bspst, *kstk, *ustk;
tf = td->td_frame;
bzero(mc, sizeof(*mc));
s = tf->tf_special;
s.pfs = s.cfm;
s.rp = s.iip;
s.cfm = s.iip = 0;
if (s.ndirty != 0) {
__asm __volatile("mov ar.rsc=0;;");
__asm __volatile("mov %0=ar.bspstore" : "=r"(bspst));
@ -1068,19 +1076,32 @@ get_mcontext(struct thread *td, mcontext_t *mc, int clear_ret)
}
s.bspstore = (uintptr_t)ustk;
}
if (tf->tf_flags & FRAME_SYSCALL) {
s.pfs = s.cfm;
s.rp = s.iip;
s.cfm = s.iip = 0;
/*
* Put the syscall return values in the context. We need this
* for swapcontext() to work. Note that we don't use gr11 in
* the kernel, but the runtime specification defines it as a
* return register, just like gr8-gr10.
*/
mc->mc_flags |= _MC_FLAGS_RETURN_VALID;
if (!clear_ret) {
mc->mc_scratch.gr8 = tf->tf_scratch.gr8;
mc->mc_scratch.gr9 = tf->tf_scratch.gr9;
mc->mc_scratch.gr10 = tf->tf_scratch.gr10;
mc->mc_scratch.gr11 = tf->tf_scratch.gr11;
}
} else {
mc->mc_flags |= _MC_FLAGS_ASYNC_CONTEXT;
mc->mc_scratch = tf->tf_scratch;
mc->mc_scratch_fp = tf->tf_scratch_fp;
/* XXX High FP */
}
mc->mc_special = s;
save_callee_saved(&mc->mc_preserved);
save_callee_saved_fp(&mc->mc_preserved_fp);
/*
* Put the syscall return values in the context. We need this
* for swapcontext() to work. Note that we don't use gr11 in
* the kernel, but the runtime specification defines it as a
* return register, just like gr8-gr10.
*/
mc->mc_scratch.gr8 = (clear_ret) ? 0 : tf->tf_scratch.gr8;
mc->mc_scratch.gr9 = (clear_ret) ? 0 : tf->tf_scratch.gr9;
mc->mc_scratch.gr10 = (clear_ret) ? 0 : tf->tf_scratch.gr10;
mc->mc_scratch.gr11 = (clear_ret) ? 0 : tf->tf_scratch.gr11;
return (0);
}
@ -1092,19 +1113,34 @@ set_mcontext(struct thread *td, const mcontext_t *mc)
tf = td->td_frame;
s = mc->mc_special;
s.cfm = s.pfs;
s.iip = s.rp;
s.pfs = tf->tf_special.pfs;
s.rp = tf->tf_special.rp;
/* Only copy the user mask from the new context. */
s.psr = (s.psr & 0x1f) | (tf->tf_special.psr & ~0x1f);
if (mc->mc_flags & _MC_FLAGS_ASYNC_CONTEXT) {
tf->tf_scratch = mc->mc_scratch;
tf->tf_scratch_fp = mc->mc_scratch_fp;
/* XXX High FP */
} else {
s.cfm = s.pfs;
s.pfs = tf->tf_special.pfs;
s.iip = s.rp;
s.rp = tf->tf_special.rp;
if ((mc->mc_flags & _MC_FLAGS_SCRATCH_VALID) == 0) {
if (mc->mc_flags & _MC_FLAGS_RETURN_VALID) {
tf->tf_scratch.gr8 = mc->mc_scratch.gr8;
tf->tf_scratch.gr9 = mc->mc_scratch.gr9;
tf->tf_scratch.gr10 = mc->mc_scratch.gr10;
tf->tf_scratch.gr11 = mc->mc_scratch.gr11;
}
} else
tf->tf_scratch = mc->mc_scratch;
}
tf->tf_special = s;
restore_callee_saved(&mc->mc_preserved);
restore_callee_saved_fp(&mc->mc_preserved_fp);
tf->tf_scratch.gr8 = mc->mc_scratch.gr8;
tf->tf_scratch.gr9 = mc->mc_scratch.gr9;
tf->tf_scratch.gr10 = mc->mc_scratch.gr10;
tf->tf_scratch.gr11 = mc->mc_scratch.gr11;
if (mc->mc_flags & _MC_FLAGS_KSE_SET_MBOX)
suword((caddr_t)mc->mc_special.ifa, mc->mc_special.isr);
return (0);
}

54
sys/ia64/include/ucontext.h
View File

@ -33,10 +33,60 @@
#include <machine/_regset.h>
/*
* 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.
*
* 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
* valid. IFF not set, _MC_FLAGS_RETURN_VALID indicates if the
* return registers are valid or not.
* _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.
* _MC_FLAGS_KSE_SET_MBOX
* This flag is special to setcontext(2) and swapcontext(2). It
* instructs the kernel to write the value in mc_special.isr to
* the memory address pointed to by mc_special.ifa. This allows
* the kernel to switch to a new context in a KSE based threaded
* program. Note that this is a non-srandard extension to the
* otherwise standard system calls and use of this flag should be
* limited to KSE.
* _MC_FLAGS_RETURN_VALID
* If set and _MC_FLAGS_ASYNC_CONTEXT is not set indicates that
* the ABI defined return registers are valid. Both getcontext(2)
* and swapcontext(2) need to save the system call return values.
* Any synctx that does not have this flag may still have the
* return registers restored from the context.
* _MC_FLAGS_SCRATCH_VALID
* If set and _MC_FLAGS_ASYNC_CONTEXT is not set indicates that
* the scratch registers, but not the FP registers are valid.
* This flag is set in contexts passed to signal handlers. This
* flag is a superset of _MC_FLAGS_RETURN_VALID. If both flags
* are set, this flag takes precedence.
*/
typedef struct __mcontext {
unsigned long mc_flags;
#define IA64_MC_FLAGS_SCRATCH_VALID 1
#define IA64_MC_FLAGS_HIGHFP_VALID 2
#define _MC_FLAGS_ASYNC_CONTEXT 0x0001
#define _MC_FLAGS_HIGHFP_VALID 0x0002
#define _MC_FLAGS_KSE_SET_MBOX 0x0004
#define _MC_FLAGS_RETURN_VALID 0x0008
#define _MC_FLAGS_SCRATCH_VALID 0x0010
unsigned long _reserved_;
struct _special mc_special;
struct _callee_saved mc_preserved;