For gcc' __builtin_frame_address() to work, all call frames need to save
frame pointer. In particular, this is important for the upper frame that
should terminate the chain.
No objections from: jhb
PR: amd64/126543
MFC after: 1 week
- It is opt-out for now so as to give it maximum testing, but it may be
turned opt-in for stable branches depending on the consensus. You
can turn it off with WITHOUT_SSP.
- WITHOUT_SSP was previously used to disable the build of GNU libssp.
It is harmless to steal the knob as SSP symbols have been provided
by libc for a long time, GNU libssp should not have been much used.
- SSP is disabled in a few corners such as system bootstrap programs
(sys/boot), process bootstrap code (rtld, csu) and SSP symbols themselves.
- It should be safe to use -fstack-protector-all to build world, however
libc will be automatically downgraded to -fstack-protector because it
breaks rtld otherwise.
- This option is unavailable on ia64.
Enable GCC stack protection (aka Propolice) for kernel:
- It is opt-out for now so as to give it maximum testing.
- Do not compile your kernel with -fstack-protector-all, it won't work.
Submitted by: Jeremie Le Hen <jeremie@le-hen.org>
in 1993 in rev.1.5 of the i386 a.out version (csu/i386/crt0.c).
Profiling uses a magic label "eprol" to delimit the start of the part
of the text section covered by profiling. This label must be placed
before the call to main() to get main() properly profiled. It was
placed there in rev.1.1 of crt0.c. Rev.1.5 imported the initial
implementation of shared libraries in FreeBSD and misplaced the label.
Fortunately, the misplaced label was misspelled and the old label
wasn't removed, so the new label had no effect. Unfortunately, when
profiling was implemented for the ELF in 1998 in rev.1.2 of
csu/i386-elf/crt1.c, only the incorrectly placed label was copied
(after fixing its name). The bug was then copied to all other arches.
The label seems to be still misplaced in NetBSD for most arches. It
is in common.c for most arches so it is even further from being inside
the function that calls main().
I think "eprol" is short for "end of prologue", but it must be placed
before the end of the prologue so that it covers main(). crt0.c has
it before the calls atexit(_mcleanup) and monstartup(...), but it
cannot affect these calls so I moved it after the call to monstartup().
It now also covers the call to _init() but not the newer call to
_init_tls(). Profiling of _init() seems to be harmless, and the call
to _init_tls() seems to be misplaced.
Reviewed by: jdp (long ago, for a slightly different i386 version)
that use SSE. The compiler does attempt to do this in main() but not very
successfully - it still manages to use unaligned offsets from %ebp in some
cases. Also we need to have an aligned stack in case something uses SSE
via _init().
MFC After: 1 week
GP register, because it's clobbered for calls across load modules. The
previous commit inserted the call to _init_tls() between the call to
atexit() and the restoration of the GP register clobbered by it. Fix:
restore GP before we call _init_tls().
Pointy hat: dfr@
section alignnment of 16 bytes for amd64 and this breaks file(1).
Before:
./cp: ELF 64-bit LSB executable, AMD x86-64, version 1 (FreeBSD), for \
FreeBSD 127.7.9, statically linked, stripped
after: ^^^^^^^
./ls: ELF 64-bit LSB executable, AMD x86-64, version 1 (FreeBSD), for \
FreeBSD 5.0.1, dynamically linked (uses shared libs), stripped
The reason for this is that the NOTE sections are not contiguous
internally. If the note section has an alignment of 16, then anything
that looks for the data is supposed to round up the payload start to
the next multiple of the alignment. But FreeBSD/amd64 broke because the
structure is declared as a single structure, not a (header,payload) group,
where the payload had an explicit alignment roundup.
The alternative is to change things like file(1) to ignore the ELF payload
alignment rules for the PT_NOTE section only for FreeBSD.
don't call it according to the runtime specification and especially
WRT to gp this can cause trouble. The gcc 3.3.1 import broke the
ia64 runtime because the compiler saved gp prior to us being able
to set it properly. Restoring gp after the calls would then invalidate
gp and cause segmentation faults later on.
By rewriting _start() as an assembly function, we also avoided even
more gcc dependences, by trying to use gcc specific features to work
around the problem.
This version of _start() does not reference _DYNAMIC. We register the
cleanup function when it's a non-NULL pointer. The kernel will always
pass a NULL pointer and dynamic linkers may pass a non-NULL pointer.
The machine independent code to set __progname now unfortunately is
written in assembly. So be it.
- -elf in CFLAGS had no effect except to reduce portability.
- -elf in LDFLAGS had even less effect, since LDFLAGS is not used.
- -Wall in CFLAGS had no effect except to reduce portability and break
overriding of WARNS, since the setting of WARNS implies -Wall.
since it has been MFC'ed. See the log message for the previous commit
for more details. The alignment bug in gcc-3 has not been fixed, but
it is not very serious and the previous commit just moved it (as intended).
Approved by: re (murray)
-fomit-frame-pointer is not used). This is mostly moot for -current
because gcc-3 does the alignment (slightly incorrectly) in main().
This patch is intended for easy MFC'ing and should be backed out in
-current soon since it causes compiler warnings and better fixes are
possible in -current. The best fix is to do nothing here and wait for
gcc to do stack alignment right. gcc-3 aligns the stack in main(), but
does it too late for main()'s local variables and too late for anything
called before main(). A misaligned stack is now more than an efficiency
problem, since some SSE instructions in some or all (hardware)
implementations trap on misaligned operands even if alignment checking
is not enabled.
PR: 41528:
Submitted by: NIIMI Satoshi <sa2c@sa2c.net> (original version)
MFC after: 3 days
Assembler macros are tidied up and made as similar as sanely possible.
The macros are translated into C (__inline static) functions for lint.
Declaration orders are made the same.
Declarations are all ISOfied and tidied up.
Comment contents have gratuitous diffs removed.
The net result is a bunch of crt1.c's that are 90% the same.
It may be possible to now encapsulate the differences in one
MD header, and have only one MI crt1.c file (although the macros
to do this may be ugly).
Helpful comments by: obrien, bde
Alpha tested by: des
i386-elf tested by: markm
Get rid of the INTERNALSTATICLIB knob and just use plain INTERNALLIB.
INTERNALLIB now means to build static library only and don't install
anything. Added a NOINSTALLLIB knob for libpam/modules. To not
build any library at all, just do not set LIB.
