dbe3061729
kernel profiling remains broken). memmove() was broken using ALTENTRY(). ALTENTRY() is only different from ENTRY() in the profiling case, and its use in that case was sort of backwards. The backwardness magically turned memmove() into memcpy() instead of completely breaking it. Only the high resolution parts of profiling itself were broken. Use ordinary ENTRY() for memmove(). Turn bcopy() into a tail call to memmove() to reduce complications. This gives slightly different pessimizations and profiling lossage. The pessimizations are minimized by not using a frame pointer() for bcopy(). Calls to profiling functions from exception trampolines were not relocated. This caused crashes on the first exception. Fix this using function pointers. Addresses of exception handlers in trampolines were not relocated. This caused unknown offsets in the profiling data. Relocate by abusing setidt_disp as for pmc although this is slower than necessary and requires namespace pollution. pmc seems to be missing some relocations. Stack traces and lots of other things in debuggers need similar relocations. Most user addresses were misclassified as unknown kernel addresses and then ignored. Treat all unknown addresses as user. Now only user addresses in the kernel text range are significantly misclassified (as known kernel addresses). The ibrs functions didn't preserve enough registers. This is the only recent breakage on amd64. Although these functions are written in asm, in the profiling case they call profiling functions which are mostly for the C ABI, so they only have to save call-used registers. They also have to save arg and return registers in some cases and actually save them in all cases to reduce complications. They end up saving all registers except %ecx on i386 and %r10 and %r11 on amd64. Saving these is only needed for 1 caller on each of amd64 and i386. Save them there. This is slightly simpler. Remove saving %ecx in handle_ibrs_exit on i386. Both handle_ibrs_entry and handle_ibrs_exit use %ecx, but only the latter needed to or did save it. But saving it there doesn't work for the profiling case. amd64 has more automatic saving of the most common scratch registers %rax, %rcx and %rdx (its complications for %r10 are from unusual use of %r10 by SYSCALL). Thus profiling of handle_ibrs_exit_rs() was not broken, and I didn't simplify the saving by moving the saving of these registers from it to the caller.
317 lines
8.5 KiB
C
317 lines
8.5 KiB
C
/*-
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* SPDX-License-Identifier: BSD-3-Clause
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*
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* Copyright (c) 1983, 1992, 1993
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* The Regents of the University of California. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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#include <sys/param.h>
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#include <sys/gmon.h>
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#ifdef _KERNEL
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#ifndef GUPROF
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#include <sys/systm.h>
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#endif
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#include <vm/vm.h>
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#include <vm/vm_param.h>
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#include <vm/pmap.h>
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#endif
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/*
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* mcount is called on entry to each function compiled with the profiling
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* switch set. _mcount(), which is declared in a machine-dependent way
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* with _MCOUNT_DECL, does the actual work and is either inlined into a
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* C routine or called by an assembly stub. In any case, this magic is
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* taken care of by the MCOUNT definition in <machine/profile.h>.
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*
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* _mcount updates data structures that represent traversals of the
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* program's call graph edges. frompc and selfpc are the return
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* address and function address that represents the given call graph edge.
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*
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* Note: the original BSD code used the same variable (frompcindex) for
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* both frompcindex and frompc. Any reasonable, modern compiler will
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* perform this optimization.
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*/
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_MCOUNT_DECL(uintfptr_t frompc, uintfptr_t selfpc) /* _mcount; may be static, inline, etc */
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{
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#ifdef GUPROF
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int delta;
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#endif
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fptrdiff_t frompci;
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u_short *frompcindex;
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struct tostruct *top, *prevtop;
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struct gmonparam *p;
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long toindex;
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#ifdef _KERNEL
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MCOUNT_DECL(s)
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#endif
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p = &_gmonparam;
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#ifndef GUPROF /* XXX */
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/*
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* check that we are profiling
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* and that we aren't recursively invoked.
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*/
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if (p->state != GMON_PROF_ON)
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return;
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#endif
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#ifdef _KERNEL
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MCOUNT_ENTER(s);
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#else
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p->state = GMON_PROF_BUSY;
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#endif
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#ifdef _KERNEL
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/* De-relocate any addresses in a (single) trampoline. */
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#ifdef MCOUNT_DETRAMP
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MCOUNT_DETRAMP(frompc);
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MCOUNT_DETRAMP(selfpc);
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#endif
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/*
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* When we are called from an exception handler, frompc may be
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* a user address. Convert such frompc's to some representation
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* in kernel address space.
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*/
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#ifdef MCOUNT_FROMPC_USER
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frompc = MCOUNT_FROMPC_USER(frompc);
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#elif defined(MCOUNT_USERPC)
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/*
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* For separate address spaces, we can only guess that addresses
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* in the range known to us are actually kernel addresses. Outside
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* of this range, conerting to the user address is fail-safe.
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*/
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if (frompc < p->lowpc || frompc - p->lowpc >= p->textsize)
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frompc = MCOUNT_USERPC;
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#endif
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#endif /* _KERNEL */
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frompci = frompc - p->lowpc;
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if (frompci >= p->textsize)
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goto done;
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#ifdef GUPROF
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if (p->state == GMON_PROF_HIRES) {
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/*
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* Count the time since cputime() was previously called
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* against `frompc'. Compensate for overheads.
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*
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* cputime() sets its prev_count variable to the count when
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* it is called. This in effect starts a counter for
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* the next period of execution (normally from now until
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* the next call to mcount() or mexitcount()). We set
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* cputime_bias to compensate for our own overhead.
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*
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* We use the usual sampling counters since they can be
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* located efficiently. 4-byte counters are usually
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* necessary. gprof will add up the scattered counts
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* just like it does for statistical profiling. All
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* counts are signed so that underflow in the subtractions
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* doesn't matter much (negative counts are normally
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* compensated for by larger counts elsewhere). Underflow
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* shouldn't occur, but may be caused by slightly wrong
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* calibrations or from not clearing cputime_bias.
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*/
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delta = cputime() - cputime_bias - p->mcount_pre_overhead;
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cputime_bias = p->mcount_post_overhead;
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KCOUNT(p, frompci) += delta;
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*p->cputime_count += p->cputime_overhead;
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*p->mcount_count += p->mcount_overhead;
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}
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#endif /* GUPROF */
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#ifdef _KERNEL
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/*
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* When we are called from an exception handler, frompc is faked
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* to be for where the exception occurred. We've just solidified
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* the count for there. Now convert frompci to an index that
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* represents the kind of exception so that interruptions appear
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* in the call graph as calls from those index instead of calls
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* from all over.
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*/
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frompc = MCOUNT_FROMPC_INTR(selfpc);
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if ((frompc - p->lowpc) < p->textsize)
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frompci = frompc - p->lowpc;
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#endif
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/*
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* check that frompc is a reasonable pc value.
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* for example: signal catchers get called from the stack,
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* not from text space. too bad.
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*/
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if (frompci >= p->textsize)
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goto done;
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frompcindex = &p->froms[frompci / (p->hashfraction * sizeof(*p->froms))];
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toindex = *frompcindex;
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if (toindex == 0) {
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/*
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* first time traversing this arc
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*/
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toindex = ++p->tos[0].link;
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if (toindex >= p->tolimit)
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/* halt further profiling */
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goto overflow;
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*frompcindex = toindex;
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top = &p->tos[toindex];
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top->selfpc = selfpc;
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top->count = 1;
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top->link = 0;
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goto done;
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}
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top = &p->tos[toindex];
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if (top->selfpc == selfpc) {
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/*
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* arc at front of chain; usual case.
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*/
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top->count++;
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goto done;
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}
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/*
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* have to go looking down chain for it.
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* top points to what we are looking at,
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* prevtop points to previous top.
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* we know it is not at the head of the chain.
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*/
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for (; /* goto done */; ) {
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if (top->link == 0) {
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/*
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* top is end of the chain and none of the chain
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* had top->selfpc == selfpc.
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* so we allocate a new tostruct
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* and link it to the head of the chain.
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*/
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toindex = ++p->tos[0].link;
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if (toindex >= p->tolimit)
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goto overflow;
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top = &p->tos[toindex];
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top->selfpc = selfpc;
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top->count = 1;
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top->link = *frompcindex;
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*frompcindex = toindex;
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goto done;
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}
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/*
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* otherwise, check the next arc on the chain.
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*/
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prevtop = top;
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top = &p->tos[top->link];
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if (top->selfpc == selfpc) {
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/*
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* there it is.
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* increment its count
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* move it to the head of the chain.
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*/
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top->count++;
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toindex = prevtop->link;
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prevtop->link = top->link;
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top->link = *frompcindex;
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*frompcindex = toindex;
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goto done;
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}
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}
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done:
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#ifdef _KERNEL
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MCOUNT_EXIT(s);
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#else
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p->state = GMON_PROF_ON;
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#endif
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return;
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overflow:
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p->state = GMON_PROF_ERROR;
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#ifdef _KERNEL
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MCOUNT_EXIT(s);
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#endif
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return;
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}
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/*
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* Actual definition of mcount function. Defined in <machine/profile.h>,
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* which is included by <sys/gmon.h>.
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*/
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MCOUNT
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#ifdef GUPROF
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void
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mexitcount(uintfptr_t selfpc)
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{
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struct gmonparam *p;
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uintfptr_t selfpcdiff;
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p = &_gmonparam;
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#ifdef MCOUNT_DETRAMP
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MCOUNT_DETRAMP(selfpc);
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#endif
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selfpcdiff = selfpc - (uintfptr_t)p->lowpc;
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if (selfpcdiff < p->textsize) {
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int delta;
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/*
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* Count the time since cputime() was previously called
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* against `selfpc'. Compensate for overheads.
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*/
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delta = cputime() - cputime_bias - p->mexitcount_pre_overhead;
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cputime_bias = p->mexitcount_post_overhead;
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KCOUNT(p, selfpcdiff) += delta;
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*p->cputime_count += p->cputime_overhead;
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*p->mexitcount_count += p->mexitcount_overhead;
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}
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}
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#ifndef __GNUCLIKE_ASM
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#error "This file uses null asms to prevent timing loops being optimized away."
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#endif
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void
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empty_loop()
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{
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int i;
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for (i = 0; i < CALIB_SCALE; i++)
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__asm __volatile("");
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}
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void
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nullfunc()
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{
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__asm __volatile("");
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}
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void
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nullfunc_loop()
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{
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int i;
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for (i = 0; i < CALIB_SCALE; i++)
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nullfunc();
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}
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#endif /* GUPROF */
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