Commit Graph

123 Commits

Author SHA1 Message Date
kib
3bbc91d138 Do not qualify the mcontext_t *mcp argument for set_mcontext(9) as
const.  On x86, even after the machine context is supposedly read into
the struct ucontext, lazy FPU state save code might only mark the FPU
data as hardware-owned.  Later, set_fpcontext() needs to fetch the
state from hardware, modifying the *mcp.

The set_mcontext(9) is called from sigreturn(2) and setcontext(2)
implementations and old create_thread(2) interface, which throw the
*mcp out after the set_mcontext() call.

Reported by:	dim
Discussed with:	jhb
Sponsored by:	The FreeBSD Foundation
MFC after:	1 week
2015-01-31 21:43:46 +00:00
kib
d0d6e7c817 Change the way the lcall $7,$0 is reflected to usermode. Instead of
setting call gate, which must be 64 bit, put a code segment descriptor
into ldt slot 0.

This way, syscall shim does not switch temporary to 64bit trampoline,
and does not create a window where signal delivery interrupts 64 bit
mode (signal handler cannot return).  The cost is shim running with
non-zero based segment in %cs, which requires vfork() handling make
more assumptions.

Sponsored by:	The FreeBSD Foundation
MFC after:	1 week
2014-12-27 23:19:08 +00:00
kib
ad7bf17db7 Replace some calls to fuword() by fueword() with proper error checking.
Sponsored by:	The FreeBSD Foundation
Tested by:	pho
MFC after:	3 weeks
2014-10-28 15:28:20 +00:00
emaste
9dcbb8e88d x86: Allow users to change PSL_RF via ptrace(PT_SETREGS...)
Debuggers may need to change PSL_RF.  Note that tf_eflags is already stored
in the signal context during signal handling and PSL_RF previously could be
modified via sigreturn, so this change should not provide any new ability
to userspace.

For background see the thread at:
http://lists.freebsd.org/pipermail/freebsd-i386/2007-September/005910.html

Reviewed by:	jhb, kib
Sponsored by:	DARPA, AFRL
2013-11-14 15:37:20 +00:00
kib
eaa828d3a5 Use slightly more idiomatic expression to get the address of array.
Tested by:	dim, pgj
Sponsored by:	The FreeBSD Foundation
MFC after:	1 week
2013-05-27 18:39:39 +00:00
kib
4f651f991c The _MC_HASFPXSTATE and _MC_IA32_HASFPXSTATE flags have the same bit
value on purpose, but the ia32 context handling code is logically more
correct to use the _MC_IA32_HASFPXSTATE name for the flag.

Tested by:	dim, pgj
Sponsored by:	The FreeBSD Foundation
MFC after:	1 week
2013-05-27 18:36:46 +00:00
kib
1ab68ccb64 The ia32_get_mcontext() does not need to set PCB_FULL_IRET. The
usermode context state is not changed by the get operation, and
get_mcontext() does not require full iret as well.

Tested by:	dim, pgj
Sponsored by:	The FreeBSD Foundation
MFC after:	1 week
2013-05-27 18:31:15 +00:00
dchagin
b6dc2308e1 Retire write-only PCB_GS32BIT pcb flag on amd64. 2013-05-09 21:42:43 +00:00
kib
11621fbf7f Real hardware, as opposed to QEMU, does not allow to have a call gate
in long mode which transfers control to 32bit code segment. Unbreak
the lcall $7,$0 implementation on amd64 by putting the 64bit user code
segment' selector into call gate, and execute the 64bit trampoline
which converts the return frame into 32bit format and switches back to
32bit mode for executing int $0x80 trampoline.

Note that all jumps over the hoops are performed in the user mode.

MFC after:	1 week
2012-08-14 12:13:27 +00:00
tijl
35c7447060 Eliminate ia32_reg.h by moving its contents to x86 and ia64 reg.h.
Reviewed by:	kib
2012-03-18 19:12:11 +00:00
kib
361bfae5c2 Add support for the extended FPU states on amd64, both for native
64bit and 32bit ABIs.  As a side-effect, it enables AVX on capable
CPUs.

In particular:

- Query the CPU support for XSAVE, list of the supported extensions
  and the required size of FPU save area. The hw.use_xsave tunable is
  provided for disabling XSAVE, and hw.xsave_mask may be used to
  select the enabled extensions.

- Remove the FPU save area from PCB and dynamically allocate the
  (run-time sized) user save area on the top of the kernel stack,
  right above the PCB. Reorganize the thread0 PCB initialization to
  postpone it after BSP is queried for save area size.

- The dumppcb, stoppcbs and susppcbs now do not carry the FPU state as
  well. FPU state is only useful for suspend, where it is saved in
  dynamically allocated suspfpusave area.

- Use XSAVE and XRSTOR to save/restore FPU state, if supported and
  enabled.

- Define new mcontext_t flag _MC_HASFPXSTATE, indicating that
  mcontext_t has a valid pointer to out-of-struct extended FPU
  state. Signal handlers are supplied with stack-allocated fpu
  state. The sigreturn(2) and setcontext(2) syscall honour the flag,
  allowing the signal handlers to inspect and manipilate extended
  state in the interrupted context.

- The getcontext(2) never returns extended state, since there is no
  place in the fixed-sized mcontext_t to place variable-sized save
  area. And, since mcontext_t is embedded into ucontext_t, makes it
  impossible to fix in a reasonable way.  Instead of extending
  getcontext(2) syscall, provide a sysarch(2) facility to query
  extended FPU state.

- Add ptrace(2) support for getting and setting extended state; while
  there, implement missed PT_I386_{GET,SET}XMMREGS for 32bit binaries.

- Change fpu_kern KPI to not expose struct fpu_kern_ctx layout to
  consumers, making it opaque. Internally, struct fpu_kern_ctx now
  contains a space for the extended state. Convert in-kernel consumers
  of fpu_kern KPI both on i386 and amd64.

First version of the support for AVX was submitted by Tim Bird
<tim.bird am sony com> on behalf of Sony. This version was written
from scratch.

Tested by:	pho (previous version), Yamagi Burmeister <lists yamagi org>
MFC after:	1 month
2012-01-21 17:45:27 +00:00
kib
55d0a85118 Inline the syscallenter() and syscallret(). This reduces the time measured
by the syscall entry speed microbenchmarks by ~10% on amd64.

Submitted by:	jhb
Approved by:	re (bz)
MFC after:	2 weeks
2011-09-11 16:05:09 +00:00
kib
abf14b630a Fix vfork. Add comments. 2011-06-18 12:13:28 +00:00
jhb
6ff99aec8c Catch up to PCB_FULL_IRET becoming a pcb flag rather than a full field.
MFC after:	3 days
2011-04-08 13:30:48 +00:00
kib
7c2eaa21fe Add support for executing the FreeBSD 1/i386 a.out binaries on amd64.
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
2011-04-01 11:16:29 +00:00
kib
7bb770f505 Clear the padding when returning context to the usermode, for
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
2011-02-05 15:10:27 +00:00
jkim
4b834288ce Remove redundant, bogus, and even harmful uses of setting TS bit in CR0.
It is done from fpstate_drop() when it is really necessary.

Reviewed by:	kib
MFC after:	1 week
2011-01-14 21:09:01 +00:00
kib
06eb8de1e1 Create shared (readonly) page. Each ABI may specify the use of page by
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
2011-01-08 16:13:44 +00:00
jkim
24b08bca03 Improve PCB flags handling and make it more robust. Add two new functions
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
2010-12-22 00:18:42 +00:00
kib
b27fb35838 Retire write-only PCB_FULLCTX pcb flag on amd64.
Reminded by:	Petr Salinger <Petr.Salinger seznam cz>
Tested by:	pho
MFC after:	1 week
2010-12-07 12:17:43 +00:00
kib
60c89c994a Remove npxgetregs(), npxsetregs(), fpugetregs() and fpusetregs()
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
2010-11-26 14:50:42 +00:00
jhb
d02cab2556 Remove unused KTRACE includes. 2010-08-19 16:41:27 +00:00
kib
8e1e89f01b Prefer struct sysentvec sv_psstrings to hardcoding FREEBSD32_PS_STRINGS
in the compat32 code. Use sv_usrstack instead of FREEBSD32_USRSTACK as well.

MFC after:	1 week
2010-08-07 11:57:13 +00:00
jhb
de324e256c Move prototypes for kern_sigtimedwait() and kern_sigprocmask() to
<sys/syscallsubr.h> where all other kern_<syscall> prototypes live.
2010-06-30 18:03:42 +00:00
kib
8dcd1daee8 Clear DF bit in eflags/rflags on the kernel entry. The i386 and amd64
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
2010-06-23 20:44:07 +00:00
kib
188338f3b7 In the ia32_{get,set}_fpcontext(), use fpu{get,set}userregs instead
of fpu{get,set}regs.

Noted by:	bde
MFC after:	1 month
2010-06-17 12:35:17 +00:00
kib
8e31ba530c Remove two obsoleted comments, add a note about 32bit compatibility.
MFC after:	1 month
2010-06-15 18:16:04 +00:00
kib
2d77212fe4 Introduce the x86 kernel interfaces to allow kernel code to use
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
2010-06-05 15:59:59 +00:00
kib
4208ccbe79 Reorganize syscall entry and leave handling.
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
2010-05-23 18:32:02 +00:00
kib
250ce04089 As was done in r155238 for i386 and in r155239 for amd64, clear the carry
flag for ia32 binary executed on amd64 host in get_mcontext().

PR:	kern/92110 (one more time)
Reported by:	stas
MFC after:	1 week
2010-04-21 11:17:16 +00:00
kib
24680f5388 Change printf() calls to uprintf() for sigreturn() and trap() complaints
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
2010-04-13 10:12:58 +00:00
nwhitehorn
d63c82a6ac Change the arguments of exec_setregs() so that it receives a pointer
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
2010-03-25 14:24:00 +00:00
trasz
dcf19c32ba Fix array overflow. This routine is only called from procfs,
which is not mounted by default, and I've been unable to trigger
a panic without this fix applied anyway.

Reviewed by:	kib, cperciva
2010-01-24 12:13:38 +00:00
kib
ddbe48bd56 For PT_TO_SCE stop that stops the ptraced process upon syscall entry,
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
2010-01-23 11:45:35 +00:00
kib
38d112ae45 For ia32 syscall(), call cpu_set_syscall_retval(). Update comment inside
cpu_set_syscall_retval() accordingly.

MFC after:	1 week
2009-12-12 20:11:31 +00:00
kib
ce081b037e In r197963, a race with thread being selected for signal delivery
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
2009-10-27 10:47:58 +00:00
kib
1596f53aae Restore the segment registers and segment base MSRs for amd64 syscall
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)
2009-07-09 09:34:11 +00:00
kib
253f7779bc Save and restore segment registers on amd64 when entering and leaving
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
2009-04-01 13:09:26 +00:00
jhb
e1b708897e A better fix for handling different FPU initial control words for different
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
2009-03-05 19:42:11 +00:00
obrien
7a153194ec Change some movl's to mov's. Newer GAS no longer accept 'movl' instructions
for moving between a segment register and a 32-bit memory location.

Looked at by:	jhb
2009-01-31 11:37:21 +00:00
kib
59a00054ac - When executing FreeBSD/amd64 binaries from FreeBSD/i386 or Linux/i386
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
2008-09-02 17:52:11 +00:00
kib
19bf5e2807 Bring back the save/restore of the %ds, %es, %fs and %gs registers for
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
2008-07-30 11:30:55 +00:00
peter
075e9da352 Protect the setting of the fsbase/gsbase MSR registers and the
pcb_[fg]sbase values with a critical section, like the rest of the kernel.
2008-03-23 22:44:56 +00:00
kib
be9c86776f Since version 4.3, gcc changed its behaviour concerning the i386/amd64
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
2008-03-13 10:54:38 +00:00
attilio
e9fc4edc44 Optimize vmmeter locking.
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)
2007-06-10 21:59:14 +00:00
attilio
e333d0ff0e Rework the PCPU_* (MD) interface:
- 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)
2007-06-04 21:38:48 +00:00
kmacy
2061110785 Newer versions of gcc don't support treating structures passed by value
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
2006-12-17 06:48:40 +00:00
davidxu
0fa66af83d Move some declaration of 32-bit signal structures into file
freebsd32-signal.h, implement sigtimedwait and sigwaitinfo system calls.
2006-10-05 01:56:11 +00:00
davidxu
98bfdf3a78 Stop reloading %fs and %gs, since it causes the base address from
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.
2006-09-23 13:42:09 +00:00
jhb
3a707d012d Retire SYF_ARGMASK and remove both SYF_MPSAFE and SYF_ARGMASK. sy_narg is
now back to just being an argument count.
2006-07-28 20:22:58 +00:00