arg0 should be an offset of the return point within the function, arg1
should be the return value. Previously the return probe had arguments as
if for the entry probe.
Tested on armv7.
andrew noted that the same problem seems to be present on arm64, mips,
and riscv.
I am not sure if I will get around to fixing those. So, platform users
or anyone looking to make a contribution please be aware of this
opportunity.
Reviewed by: markj
MFC after: 1 week
Differential Revision: https://reviews.freebsd.org/D25685
'.' function names exist only in ELFv1. ELFv2 does away with function
descriptors, and look more like they do on powerpc(32) and most other
platforms, as direct function pointers. Stop blacklisting regular function
names in ELFv2.
Submitted by: Brandon Bergren
Differential Revision: https://reviews.freebsd.org/D20346
The FBT fuction boundary prober was setting one return probe marker value,
but the dtrace handler was expecting another. This causes a hang when
tracing return probes.
- Remove the arm64-specific cpu_*cache* and cpu_tlb_flush* functions.
Instead, add RISC-V specific inline functions in cpufunc.h for the
fence.i and sfence.vma instructions.
- Catch up to changes in the arm64 pmap and remove all the cpu_dcache_*
calls, pmap_is_current, pmap_l3_valid_cacheable, and PTE_NEXT bits from
pmap.
- Remove references to the unimplemented riscv_setttb().
- Remove unused cpu_nullop.
- Add a link to the SBI doc to sbi.h.
- Add support for a 4th argument in SBI calls. It's not documented but
it seems implied for the asid argument to SBI_REMOVE_SFENCE_VMA_ASID.
- Pass the arguments from sbi_remote_sfence*() to the SEE. BBL ignores
them so this is just cosmetic.
- Flush icaches on other CPUs when they resume from kdb in case the
debugger wrote any breakpoints while the CPUs were paused in the IPI_STOP
handler.
- Add SMP vs UP versions of pmap_invalidate_* similar to amd64. The
UP versions just use simple fences. The SMP versions use the
sbi_remove_sfence*() functions to perform TLB shootdowns. Since we
don't have a valid pm_active field in the riscv pmap, just IPI all
CPUs for all invalidations for now.
- Remove an extraneous TLB flush from the end of pmap_bootstrap().
- Don't do a TLB flush when writing new mappings in pmap_enter(), only if
modifying an existing mapping. Note that for COW faults a TLB flush is
only performed after explicitly clearing the old mapping as is done in
other pmaps.
- Sync the i-cache on all harts before updating the PTE for executable
mappings in pmap_enter and pmap_enter_quick. Previously the i-cache was
only sync'd after updating the PTE in pmap_enter.
- Use sbi_remote_fence() instead of smp_rendezvous in pmap_sync_icache().
Reviewed by: markj
Approved by: re (gjb, kib)
Sponsored by: DARPA
Differential Revision: https://reviews.freebsd.org/D17414
With GNU ifuncs, multiple FBT probes may correspond to the same
instruction. fbt_invop() assumed that this could not happen and
would return after the first probe found in the global FBT hash
table, which might not be the one that's enabled. Fix the problem
on x86 by linking probes that share a tracepoint and having each
linked probe fire when the tracepoint is hit.
PR: 230846
Approved by: re (gjb)
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D16921
Turn on the required options in the ERL config file, and ensure
that the fbt module is listed as a dependency for mips in
the modules/dtrace/dtraceall/dtraceall.c file.
PR: 220346
Reviewed by: gnn, markj
MFC after: 2 weeks
Differential Revision: https://reviews.freebsd.org/D12227
r314370 changed EXC_DTRACE to a different instruction, but neglected to
make the same change to fbt, so dtrace didn't actually pick it up,
resulting in entering KDB instead of trapping for dtrace.
MFC after: 1 week
the fifth argument to functions being traced, however there was an error
where the userspace stack was being used. This may be invalid leading to
a kernel panic if this address is unmapped.
Submitted by: Graeme Jenkinson <graeme.jenkinson@cl.cam.ac.uk>
MFC after: 1 week
Differential Revision: https://reviews.freebsd.org/D9229
These functions may be called in DTrace probe context, so they cannot be
safely traced. Moreover, they are currently only used by DTrace, so their
corresponding FBT probes are not particularly useful.
MFC after: 2 weeks
This restriction was inherited from upstream but is not relevant on FreeBSD.
Furthermore, it hindered the tracing of locking primitive subroutines.
MFC after: 1 week
Currently this argument is a pointer into the stack which is used by FBT
to fetch the first five probe arguments. On all non-x86 architectures it's
simply the trapframe address, so this change has no functional impact. On
amd64 it's a pointer into the trapframe such that stack[1 .. 5] gives the
first five argument registers, which are deliberately grouped together in
the amd64 trapframe definition.
A trapframe argument simplifies the invop handlers on !x86 and makes the
x86 FBT invop handler easier to understand. Moreover, it allows for invop
handlers that may want to modify the register set of the interrupted thread.
first instruction to see if it's either a pushm with lr, or a sub with sp.
The former is the common case, with the latter used with va_args.
This removes 12 probes. These are all hand-written assembly, with a few C
functions with no stack usage.
Submitted by: Howard Su <howard0su@gmail.com>
Differential Revision: https://reviews.freebsd.org/D4419
Boundary Trace to assembly to reduce the overhead of these checks.
Submitted by: Howard Su <howard0su@gmail.com>
Relnotes: Yes
Differential Revision: https://reviews.freebsd.org/D4266
emulate the instructions used in function entry and exit.
For function entry ARM will use a push instruction to push up to 16
registers to the stack. While we don't expect all 16 to be used we need to
handle any combination the compiler may generate, even if it doesn't make
sense (e.g. pushing the program counter).
On function return we will either have a pop or branch instruction. The
former is similar to the push instruction, but with care to make sure we
update the stack pointer and program counter correctly in the cases they
are either in the list of registers or not. For branch we need to take the
24-bit offset, sign-extend it, and add that number of 4-byte words to the
program counter. Care needs to be taken as, due to historical reasons, the
address the branch is relative to is not the current instruction, but 8
bytes later.
This allows us to use the following probes on ARM boards:
dtrace -n 'fbt::malloc:entry { stack() }'
and
dtrace -n 'fbt:🆓return { stack() }'
Differential Revision: https://reviews.freebsd.org/D2007
Reviewed by: gnn, rpaulo
Sponsored by: ABT Systems Ltd
In the old days callout(9) had 1 tick precision and that was inadequate
for some uses, e.g. DTrace profile module, so we had to emulate cyclic
API and behavior. Now we can directly use callout(9) in the very few
places where cyclic was used.
Differential Revision: https://reviews.freebsd.org/D1161
Reviewed by: gnn, jhb, markj
MFC after: 2 weeks
* Use a constant to define the number of stack frames in a probe exception.
* Only allow function symbols in powerpc64 ('.' prefixed)
* Set the fbtp_roffset for return probes, so the correct dtrace_probe call is
made.
MFC after: 1 week
Summary:
Fix the stack tracing for dtrace/powerpc by using the trapexit/asttrapexit
return address sentinels instead of checking within the kernel address space.
As part of this, I had to add new inline functions. FBT traces the kernel, so
we have to have special case handling for this, since a trap will create a full
new trap frame, and there's no way to pass around the 'real' stack. I handle
this by special-casing 'aframes == 0' with the trap frame. If aframes counts
out to the trap frame, then assume we're looking for the full kernel trap frame,
so switch to the real stack pointer.
Test Plan: Tested on powerpc64
Reviewers: rpaulo, markj, nwhitehorn
Reviewed By: markj, nwhitehorn
Differential Revision: https://reviews.freebsd.org/D788
MFC after: 3 week
Relnotes: Yes
tracepoints would continue to generate traps, which would be ignored but
could consume noticeable amounts of CPU if, say, all functions in the kernel
were instrumented.
X-MFC-With: r270067
duplicating the entire implementation for both x86 and powerpc. This makes
it easier to add support for other architectures and has no functional
impact.
Phabric: D613
Reviewed by: gnn, jhibbits, rpaulo
Tested by: jhibbits (powerpc)
MFC after: 2 weeks
probes declared in a kernel module when that module is unloaded. In
particular,
* Unloading a module with active SDT probes will cause a panic. [1]
* A module's (FBT/SDT) probes aren't destroyed when the module is unloaded;
trying to use them after the fact will generally cause a panic.
This change fixes both problems by porting the DTrace module load/unload
handlers from illumos and registering them with the corresponding
EVENTHANDLER(9) handlers. This allows the DTrace framework to destroy all
probes defined in a module when that module is unloaded, and to prevent a
module unload from proceeding if some of its probes are active. The latter
problem has already been fixed for FBT probes by checking lf->nenabled in
kern_kldunload(), but moving the check into the DTrace framework generalizes
it to all kernel providers and also fixes a race in the current
implementation (since a probe may be activated between the check and the
call to linker_file_unload()).
Additionally, the SDT implementation has been reworked to define SDT
providers/probes/argtypes in linker sets rather than using SYSINIT/SYSUNINIT
to create and destroy SDT probes when a module is loaded or unloaded. This
simplifies things quite a bit since it means that pretty much all of the SDT
code can live in sdt.ko, and since it becomes easier to integrate SDT with
the DTrace framework. Furthermore, this allows FreeBSD to be quite flexible
in that SDT providers spanning multiple modules can be created on the fly
when a module is loaded; at the moment it looks like illumos' SDT
implementation requires all SDT probes to be statically defined in a single
kernel table.
PR: 166927, 166926, 166928
Reported by: davide [1]
Reviewed by: avg, trociny (earlier version)
MFC after: 1 month
