In particular:
- implement compat shims for old stat(2) variants and ogetdirentries(2);
- implement delivery of signals with ancient stack frame layout and
corresponding sigreturn(2);
- implement old getpagesize(2);
- provide a user-mode trampoline and LDT call gate for lcall $7,$0;
- port a.out image activator and connect it to the build as a module
on amd64.
The changes are hidden under COMPAT_43.
MFC after: 1 month
MI ucontext_t and x86 MD parts.
Kernel allocates the structures on the stack, and not clearing
reserved fields and paddings causes leakage.
Noted and discussed with: bde
MFC after: 2 weeks
setting SV_SHP flag and providing pointer to the vm object and mapping
address. Provide simple allocator to carve space in the page, tailored
to put the code with alignment restrictions.
Enable shared page use for amd64, both native and 32bit FreeBSD
binaries. Page is private mapped at the top of the user address
space, moving a start of the stack one page down. Move signal
trampoline code from the top of the stack to the shared page.
Reviewed by: alc
for manipulating pcb_flags. These inline functions are very similar to
atomic_set_char(9) and atomic_clear_char(9) but without unnecessary LOCK
prefix for SMP. Add comments about the rationale[1]. Use these functions
wherever possible. Although there are some places where it is not strictly
necessary (e.g., a PCB is copied to create a new PCB), it is done across
the board for sake of consistency. Turn pcb_full_iret into a PCB flag as
it is safe now. Move rarely used fields before pcb_flags and reduce size
of pcb_flags to one byte. Fix some style(9) nits in pcb.h while I am in
the neighborhood.
Reviewed by: kib
Submitted by: kib[1]
MFC after: 2 months
functions, they are unused. Remove 'user' from npxgetuserregs()
etc. names.
For {npx,fpu}{get,set}regs(), always use pcb->pcb_user_save for FPU
context storage. This eliminates the need for ugly copying with
overwrite of the newly added and reserved fields in ucontext on i386
to satisfy alignment requirements for fpusave() and fpurstor().
pc98 version was copied from i386.
Suggested and reviewed by: bde
Tested by: pho (i386 and amd64)
MFC after: 1 week
ABI specifies the DF should be zero, and newer compilers do not clear
DF before using DF-sensitive instructions.
The DF clearing for signal handlers was done some time ago.
MFC after: 1 week
FPU/SSE hardware. Caller should provide a save area that is chained
into the stack of the areas; pcb save_area for usermode FPU state is
on top. The pcb now contains a pointer to the current FPU saved area,
used during FPUDNA handling and context switches. There is also a
facility to allow the kernel thread to use pcb save_area.
Change the dreaded warnings "npxdna in kernel mode!" into the panics
when FPU usage is not registered.
KPI discussed with: fabient
Tested by: pho, fabient
Hardware provided by: Sentex Communications
MFC after: 1 month
Extend struct sysvec with three new elements:
sv_fetch_syscall_args - the method to fetch syscall arguments from
usermode into struct syscall_args. The structure is machine-depended
(this might be reconsidered after all architectures are converted).
sv_set_syscall_retval - the method to set a return value for usermode
from the syscall. It is a generalization of
cpu_set_syscall_retval(9) to allow ABIs to override the way to set a
return value.
sv_syscallnames - the table of syscall names.
Use sv_set_syscall_retval in kern_sigsuspend() instead of hardcoding
the call to cpu_set_syscall_retval().
The new functions syscallenter(9) and syscallret(9) are provided that
use sv_*syscall* pointers and contain the common repeated code from
the syscall() implementations for the architecture-specific syscall
trap handlers.
Syscallenter() fetches arguments, calls syscall implementation from
ABI sysent table, and set up return frame. The end of syscall
bookkeeping is done by syscallret().
Take advantage of single place for MI syscall handling code and
implement ptrace_lwpinfo pl_flags PL_FLAG_SCE, PL_FLAG_SCX and
PL_FLAG_EXEC. The SCE and SCX flags notify the debugger that the
thread is stopped at syscall entry or return point respectively. The
EXEC flag augments SCX and notifies debugger that the process address
space was changed by one of exec(2)-family syscalls.
The i386, amd64, sparc64, sun4v, powerpc and ia64 syscall()s are
changed to use syscallenter()/syscallret(). MIPS and arm are not
converted and use the mostly unchanged syscall() implementation.
Reviewed by: jhb, marcel, marius, nwhitehorn, stas
Tested by: marcel (ia64), marius (sparc64), nwhitehorn (powerpc),
stas (mips)
MFC after: 1 month
about inacessible or wrong mcontext, and for dreaded "kernel trap with
interrupts disabled" situation. The later is changed when trap is
generated from user mode (shall never be ?).
Normalize the messages to include both pid and thread name.
MFC after: 1 week
to the image_params struct instead of several members of that struct
individually. This makes it easier to expand its arguments in the future
without touching all platforms.
Reviewed by: jhb
syscall arguments are collected before ptracestop() is called. As a
consequence, debugger cannot modify syscall or its arguments.
For i386, amd64 and ia32 on amd64 MD syscall(), reread syscall number
and arguments after ptracestop(), if debugger modified anything in the
process environment. Since procfs stopeven requires number of syscall
arguments in p_xstat, this cannot be solved by moving stop/trace point
before argument fetching.
Move the code to read arguments into separate function
fetch_syscall_args() to avoid code duplication. Note that ktrace point
for modified syscall is intentionally recorded twice, once with original
arguments, and second time with the arguments set by debugger.
PT_TO_SCX stop is executed after cpu_syscall_set_retval() already.
Reported by: Ali Polatel <alip exherbo org>
Briefly discussed with: jhb
MFC after: 3 weeks
while in kernel mode, and later changing signal mask to block the
signal, was fixed for sigprocmask(2) and ptread_exit(3). The same race
exists for sigreturn(2), setcontext(2) and swapcontext(2) syscalls.
Use kern_sigprocmask() instead of direct manipulation of td_sigmask to
reschedule newly blocked signals, closing the race.
Reviewed by: davidxu
Tested by: pho
MFC after: 1 month
return path only when neither thread was context switched while
executing syscall code nor syscall explicitely modified LDT or MSRs.
Save segment registers in trap handlers before interrupts are enabled,
to not allow context switches to happen before registers are saved.
Use separated byte in pcb for indication of fast/full return, since
pcb_flags are not synchronized with context switches.
The change puts back syscall microbenchmark numbers that were slowed
down after commit of the support for LDT on amd64.
Reviewed by: jeff
Tested (and tested, and tested ...) by: pho
Approved by: re (kensmith)
the kernel on amd64. Fill and read segment registers for mcontext and
signals. Handle traps caused by restoration of the
invalidated selectors.
Implement user-mode creation and manipulation of the process-specific
LDT descriptors for amd64, see sysarch(2).
Implement support for TSS i/o port access permission bitmap for amd64.
Context-switch LDT and TSS. Do not save and restore segment registers on
the context switch, that is handled by kernel enter/leave trampolines
now. Remove segment restore code from the signal trampolines for
freebsd/amd64, freebsd/ia32 and linux/i386 for the same reason.
Implement amd64-specific compat shims for sysarch.
Linuxolator (temporary ?) switched to use gsbase for thread_area pointer.
TODO:
Currently, gdb is not adapted to show segment registers from struct reg.
Also, no machine-depended ptrace command is added to set segment
registers for debugged process.
In collaboration with: pho
Discussed with: peter
Reviewed by: jhb
Linuxolator tested by: dchagin
ABIs:
- Store the FPU initial control word in the pcb for each thread.
- When first using the FPU, load the initial control word after restoring
the clean state if it is not the standard control word.
- Provide a correct control word for Linux/i386 binaries under
FreeBSD/amd64.
- Adjust the control word returned for fpugetregs()/npxgetregs() when a
thread hasn't used the FPU yet to reflect the real initial control
word for the current ABI.
- The Linux/i386 ABI for FreeBSD/i386 now properly sets the right control
word instead of trashing whatever the current state of the FPU is.
Reviewed by: bde
processes, clear PCB_32BIT and PCB_GS32BIT bits [1].
- Reread the fs and gs bases from the msr unconditionally, not believing
the values in pcb_fsbase and pcb_gsbase, since usermode may reload
segment registers, invalidating the cache. [2].
Both problems resulted in the wrong fs base, causing wrong tls pointer
be dereferenced in the usermode.
Reported and tested by: Vyacheslav Bocharov <adeepv at gmail com> [1]
Reported by: Bernd Walter <ticsoat cicely7 cicely de>,
Artem Belevich <fbsdlist at src cx>[2]
Reviewed by: peter
MFC after: 3 days
the 32bit images on amd64.
Change the semantic of the PCB_32BIT pcb flag to request the context
switch code to operate on the segment registers. Its previous meaning
of saving or restoring the %gs base offset is assigned to the new
PCB_GS32BIT flag.
FreeBSD 32bit image activator sets the PCB_32BIT flag, while Linux 32bit
emulation sets PCB_32BIT | PCB_GS32BIT.
Reviewed by: peter
MFC after: 2 weeks
ABI and the direction flag, that is it now assumes that the direction
flag is cleared at the entry of a function and it doesn't clear once
more if needed. This new behaviour conforms to the i386/amd64 ABI.
Modify the signal handler frame setup code to clear the DF {e,r}flags
bit on the amd64/i386 for the signal handlers.
jhb@ noted that it might break old apps if they assumed DF == 1 would be
preserved in the signal handlers, but that such apps should be rare and
that older versions of gcc would not generate such apps.
Submitted by: Aurelien Jarno <aurelien aurel32 net>
PR: 121422
Reviewed by: jhb
MFC after: 2 weeks
In particular:
- Add an explicative table for locking of struct vmmeter members
- Apply new rules for some of those members
- Remove some unuseful comments
Heavily reviewed by: alc, bde, jeff
Approved by: jeff (mentor)
- Rename PCPU_LAZY_INC into PCPU_INC
- Add the PCPU_ADD interface which just does an add on the pcpu member
given a specific value.
Note that for most architectures PCPU_INC and PCPU_ADD are not safe.
This is a point that needs some discussions/work in the next days.
Reviewed by: alc, bde
Approved by: jeff (mentor)
as if they were really passed by reference. Specifically, the dead stores
elimination pass in the GCC 4.1 optimiser breaks the non-compliant behavior
on which FreeBSD relied. This change brings FreeBSD up to date by switching
trap frames to being explicitly passed by reference.
Reviewed by: kan
Tested by: kan
GDT to be loaded into FS.base and GS.base, these values of course
are not the values set by sysarch() with I386_SET_FSBASE and
I386_SET_GSBASE, the change fixed a crash for 32bit libthr after
signal handler returned and normal code is accessing thread pointer,
for example: movl %gs:8, %eax.
mark system calls as being MPSAFE:
- Stop conditionally acquiring Giant around system call invocations.
- Remove all of the 'M' prefixes from the master system call files.
- Remove support for the 'M' prefix from the script that generates the
syscall-related files from the master system call files.
- Don't explicitly set SYF_MPSAFE when registering nfssvc.
implementations and adjust some of the checks while I'm here:
- Add a new check to make sure we don't return from a syscall in a critical
section.
- Add a new explicit check before userret() to make sure we don't return
with any locks held. The advantage here is that we can include the
syscall number and name in syscall() whereas that info is not available
in userret().
- Drop the mtx_assert()'s of sched_lock and Giant. They are replaced by
the more general checks just added.
MFC after: 2 weeks
Rename struct thread's td_sticks to td_pticks, we will need the
other name for more appropriately named use shortly. Reduce it
from uint64_t to u_int.
Clear td_pticks whenever we enter the kernel instead of recording
its value as reference for userret(). Use the absolute value of
td->pticks in userret() and eliminate third argument.
changes in MD code are trivial, before this change, trapsignal and
sendsig use discrete parameters, now they uses member fields of
ksiginfo_t structure. For sendsig, this change allows us to pass
POSIX realtime signal value to user code.
2. Remove cpu_thread_siginfo, it is no longer needed because we now always
generate ksiginfo_t data and feed it to libpthread.
3. Add p_sigqueue to proc structure to hold shared signals which were
blocked by all threads in the proc.
4. Add td_sigqueue to thread structure to hold all signals delivered to
thread.
5. i386 and amd64 now return POSIX standard si_code, other arches will
be fixed.
6. In this sigqueue implementation, pending signal set is kept as before,
an extra siginfo list holds additional siginfo_t data for signals.
kernel code uses psignal() still behavior as before, it won't be failed
even under memory pressure, only exception is when deleting a signal,
we should call sigqueue_delete to remove signal from sigqueue but
not SIGDELSET. Current there is no kernel code will deliver a signal
with additional data, so kernel should be as stable as before,
a ksiginfo can carry more information, for example, allow signal to
be delivered but throw away siginfo data if memory is not enough.
SIGKILL and SIGSTOP have fast path in sigqueue_add, because they can
not be caught or masked.
The sigqueue() syscall allows user code to queue a signal to target
process, if resource is unavailable, EAGAIN will be returned as
specification said.
Just before thread exits, signal queue memory will be freed by
sigqueue_flush.
Current, all signals are allowed to be queued, not only realtime signals.
Earlier patch reviewed by: jhb, deischen
Tested on: i386, amd64
This is good enough to be able to run a RELENG_4 gdb binary against
a RELENG_4 application, along with various other tools (eg: 4.x gcore).
We use this at work.
ia32_reg.[ch]: handle the 32 bit register file format, used by ptrace,
procfs and core dumps.
procfs_*regs.c: vary the format of proc/XXX/*regs depending on the client
and target application.
procfs_map.c: Don't print a 64 bit value to 32 bit consumers, or their
sscanf fails. They expect an unsigned long.
imgact_elf.c: produce a valid 32 bit coredump for 32 bit apps.
sys_process.c: handle 32 bit consumers debugging 32 bit targets. Note
that 64 bit consumers can still debug 32 bit targets.
IA64 has got stubs for ia32_reg.c.
Known limitations: a 5.x/6.x gdb uses get/setcontext(), which isn't
implemented in the 32/64 wrapper yet. We also make a tiny patch to
gdb pacify it over conflicting formats of ld-elf.so.1.
Approved by: re
