Commit Graph

13 Commits

Author SHA1 Message Date
Michael LeMay
3908253038 x86: Add support for (paging-based) protection domains
This patch implements a simple, lightweight form of protection domains
using a pluggable framework.  Currently, the following plugin is
available:

 - Flat memory model with paging.

The overall goal of a protection domain implementation within this
framework is to define a set of resources that should be accessible to
each protection domain and to prevent that protection domain from
accessing other resources.  The details of each implementation of
protection domains may differ substantially, but they should all be
guided by the principle of least privilege.  However, that idealized
principle is balanced against the practical objectives of limiting the
number of relatively time-consuming context switches and minimizing
changes to existing code.

For additional information, please refer to cpu/x86/mm/README.md.

This patch also causes the C compiler to be used as the default linker
and assembler.
2016-03-21 17:18:06 -07:00
Michael LeMay
f85654a82f x86, galileo: Add UEFI support
This patch adds support for optionally building EFI binaries in
addition to Multiboot ELF binaries.  It includes a script,
build_uefi.sh, that downloads tool and library sources from the EDK II
project, builds the GenFw tool that is used to create UEFI binaries,
and creates a makefile that is included from the main x86 common
makefile and enables UEFI support in the Contiki build system.  If the
script is not run prior to building Contiki, then an informational
message will be displayed with instructions for running build_uefi.sh
if UEFI support is desired.  This patch also adds the path to the
auto-generated makefile to .gitignore.

This patch modifies the linker script for the Intel Quark X1000 to
account for the output file section offsets and alignment expectations
of the EDK II GenFw project.

This patch also adds a newlib patch to remove the weak symbol
attribute from floating point stdio support routines.  See
<newlib>/newlib/README for an explanation of how the newlib developers
intended for _printf_float and _scanf_float to be linked.  Newlib
declares them as weak symbols with the intention that developers would
force them to be linked only when needed using a linker command line
option.  However, some but not all Contiki programs require them, so
we cannot simply always include or exclude them.  Instead, we remove
the weak symbol attributes and rely on the linker to automatically
determine whether or not they should be linked.  This avoids an issue
in which weak symbols were undefined in the intermediate DLL generated
as part of the UEFI build process.  That resulted in the GenFw program
emitting "ERROR 3000" messages when it encountered relocations
referencing such an undefined symbol.

Finally, this patch updates README.md to both make some revisions to
account for the UART support introduced in previous patches as well as
to provide instructions for using the UEFI support.
2015-12-21 08:06:14 -02:00
Michael LeMay
b915e7d5e3 galileo: Omit exception handling unwind tables
This patch modifies the newlib and Contiki C and C++ compiler flags to
omit exception handling unwind tables (see
http://wiki.dwarfstd.org/index.php?title=Exception_Handling).
Removing these tables saves space in debug builds and has not caused
any readily-apparent functional changes.

Here is the size listing for an example program built without this
patch:
   text	   data	    bss	    dec	    hex	filename
  76002	   1508	  21224	  98734	  181ae	all-timers.galileo

Here is the size listing for the same program with this patch:
   text	   data	    bss	    dec	    hex	filename
  72918	   1508	  21224	  95650	  175a2	all-timers.galileo

The primary motivation for this patch is to help enable UEFI support.
The .eh_frame and .eh_frame_hdr sections that are otherwise generated
are treated as code sections by the EDK2 GenFw program, since they are
read-only alloc sections.  They get grouped with the actual code
sections, ahead of the data sections.  This perturbs symbols and
complicates debugging.
2015-12-21 08:06:14 -02:00
Andre Guedes
c6ef8454a1 x86: Use -O0 instead of -Og for debug build
This patch replaces the gcc option '-Og' by '-O0' which is used when
building debugging binaries. The motivation for this change comes
from the fact that we have found at least one optimization done by
'-Og' that interfered with one of our debugging sessions.
2015-12-21 08:06:14 -02:00
Andre Guedes
6b433aede1 x86: Improve release binary size
This patch adds -ffunction-sections and -fdata-sections to the
'release' CFLAGS so each function and data is place into its
own section in the output file. It also adds --gc-section to
the 'release' LDFLAGS so the linker removes the sections which
are not referenced.

This patch also adds -ffunction-sections and -fdata-sections
options to CFLAGS from build_newlib.sh. This increases newlib
static libraries size, however, the Contiki image shrinks even
more since --gc-section removes "dead code" from newlib.

As a practical effect, all unused function and data (as well as
sections such as .eh_frame) are striped out from the final elf
binary. This shrinks our release binary drastically.

Finally, to prevent --gc-section from removing .multiboot section,
this patch adds KEEP(*(.multiboot)) to quarkX1000.ld.
2015-12-21 08:06:14 -02:00
Jesus Sanchez-Palencia
8ae392e66f x86: Reduce .eh_frame section size
When generating binaries, gcc will always add information of what it
calls "the exception handler framework" into its own section: .eh_frame.
This section is based on the DWARF format's call frame information (CFI) [1]
and holds information that can be useful for debuggers but also for language
constructs that relies on always having stack unwinding information (i.e. exceptions).
Such constructs, however, are pretty much useless for the C language and are
mainly just used on C++. Furthermore, this section is one of the loadable sections
of a binary, meaning it will take extra space on flash.

When .eh_frame is not present, debuggers can still get the exact same information
they need for unwinding a stack frame and for restoring registers thanks to yet
another section: .debug_frame. This section is generated by '-g' gcc option and
friends. It is actually defined by DWARF and, as opposed to .eh_frame, is not a
loadable section. In other words, it is 'strippable' while .eh_frame is not.

Since all we need is the debug information we can get from .debug_frame, we can
disable the generation of these large and unused information tables by using gcc's
'-fno-asynchronous-unwind-tables'. The .eh_frame section stays around but the code
size issue is heavily tackled. This is the same approach taken on other projects
that target small code size generation [2] [3].

Pratically speaking, on a DEBUG build of the all-timers appplication, before this
patch we had:
   text    data     bss     dec     hex filename
  21319    1188   12952   35459    8a83 all-timers.galileo

And now, after this patch:
   text    data     bss     dec     hex filename
  16347    1188   12952   30487    7717 all-timers.galileo

This means a ~5Kb reduction on the loadable text segment (.text + .rodata + .eh_frame).

The flag is applied regardless of build type, DEBUG or RELEASE, since it benefits both.
Note that when release builds apply --gc-sections, they will remove .eh_frame section entirely.

[1] http://comments.gmane.org/gmane.comp.standards.dwarf/222
[2] 0d74ad383b
[3] http://git.musl-libc.org/cgit/musl/commit/?id=b439c051c7eee4eb4b93fc382f993aa6305ce530
[4] https://refspecs.linuxfoundation.org/LSB_3.0.0/LSB-Core-generic/LSB-Core-generic/ehframechpt.html

Signed-off-by: Jesus Sanchez-Palencia <jesus.sanchez-palencia@intel.com>
2015-12-21 08:06:14 -02:00
Michael LeMay
0dcd5e9b5a x86: Revise CFLAGS and LDFLAGS for LLVM Clang compatibility
This patch slightly revises CFLAGS and LDFLAGS to specify the
optimization and debugging options and linker script in a way that is
compatible with using Clang as the C compiler and to invoke the linker
(i.e. CC = clang and LD = clang).
2015-12-21 08:06:14 -02:00
Andre Guedes
8a0bc49433 x86: Improve debugging experience
This patch appends some gcc options to CFLAGS when building the default
image in order to improve the debugging experience on GDB.

We use the '-ggdb' option which produces debugging information used by
GDB (including GDB extensions) with level 3 which includes preprocessor
macros information. We also use '-Og' which enables optimizations that
do not interfere with debugging. According to gcc manpage, it should be
the optimization level of choice for the standard edit-compile-debug
cycle, offering a reasonable level of optimization while maintaining
fast compilation and a good debugging experience.

Also, this patch removes the '-g' option from the default CFLAGS because
there is no point in using it when BUILD_RELEASE=1.

As expected, the overall ELF image increases (due to -ggdb3 option) while
the .text section is reduced (due to -Og). For the sake of comparison,
below follows the output of 'size'.

Before patch:
$ size -A hello-world.galileo
hello-world.galileo  :
section           size      addr
.text            13766   1048576
.rodata            241   1064960
.eh_frame         5160   1065204
.eh_frame_hdr     1212   1070364
.data             1188   1073152
.bss             12808   1077248
.debug_info      14351         0
.debug_abbrev     6281         0
.debug_aranges     768         0
.debug_line       6443         0
.debug_str        4805         0
.comment            17         0
.note               40         0
.debug_ranges       24         0
Total            67104

After patch:
$ size -A hello-world.galileo
hello-world.galileo  :
section            size      addr
.text             11718   1048576
.rodata             249   1060864
.eh_frame          5496   1061116
.eh_frame_hdr      1204   1066612
.data              1156   1069056
.bss              12808   1073152
.debug_info       16727         0
.debug_abbrev      7254         0
.debug_loc         2083         0
.debug_aranges      768         0
.debug_macro      17273         0
.debug_line       13433         0
.debug_str        42192         0
.comment             17         0
.note                40         0
Total            132418
2015-12-21 08:06:14 -02:00
Andre Guedes
c9020d95e7 x86: Build release image
This patch adds support for building release images. The main difference
between release images and default images is that the former is optimized
for size while the latter is "optimized" for debugging. To build a release
image, the BUILD_RELEASE variable should be set to 1. For instance, the
following command build a release image from the hello-world application:
$ cd examples/hello-world && make TARGET=galileo BUILD_RELEASE=1

To optimize for size we use the '-Os' option from gcc. This option also
enables the strict aliasing optimization. This generates lots of warning
messages since we use the '-Wall' option and lots of code in core/net/
break the strict-aliasing rules. Some test have shown that the strict
aliasing optimization it not taking effect in the final binary. For that
reasons, this patch manually disables the optimization. Also, the release
image is stripped.

For the sake of comparison, below follows the output from 'wc' and 'size'
for both debugging (default) and release images.

Default image:
$  wc -c hello-world.galileo
71112 hello-world.galileo
$ size hello-world.galileo
   text    data     bss     dec     hex filename
  20379    1188   12808   34375    8647 hello-world.galileo

Release image:
$ wc -c hello-world.galileo
26320 hello-world.galileo
$ size hello-world.galileo
   text    data     bss     dec     hex filename
  18146    1156   12808   32110    7d6e hello-world.galileo
2015-12-21 08:06:14 -02:00
Andre Guedes
b697646b11 x86: Cleanup Makefile.x86_common
This patch does several cleanups in Makefile.x86_common file. The
changes are described above.

1) The CFLAGNO variable was removed since it is used only to assign
   the CFLAGS variable. Also, CFLAGNO is not used outside Makefile.x86_
   common.

2) The "-I/usr/local/include" option was removed since we provide manually
   the include path from newlib in the bsp/ directory.

3) We only support building x86-based platforms on Linux so there is no
   point in setting LDFLAGS conditionally.

4) The '-export-dynamic' option was removed from LDFLAGS since we are not
    creating a dynamically linked executable.

5) Makefile.x86_quarkX1000 is the only one that includes Makefile.x86_
   common. Since it doesn't use the custom rules from Makefile.x86_
   common we remove them.
2015-12-21 08:06:14 -02:00
Andre Guedes
13bbe8a5b5 x86: Don't generate .note.gnu.build-id section
This patch adds "--build-id=none" to default LDFLAGS so
.note.gnu.build-id section is not generated. This section
contains unique identification for the built files what is
not important to us (at least at this moment).

This change simplifies all linker scripts for SoCs based on x86
(at this moment we only have Quark X1000) since we don't have to
care about it anymore.
2015-12-21 08:06:14 -02:00
Jesus Sanchez-Palencia
e4bc1a1e8c x86: Add init folder and move code accordingly
The x86/init/common/ folder holds all cpu initialization
code - idt and gdt setup, interrupts and cpu initialization.

On this folder will also sit any SoC specific implementation of
the functions called from cpu_init().
2015-12-21 08:06:14 -02:00
Jesus Sanchez-Palencia
b2fa72bb98 x86: Break Makefile.x86 into common and pc specific ones
Now the cpu/x86/ provides a Makefile.x86_common and a
Makefile.x86_pc. The former includes the common Makefile
and adds legacy pc specific implementations (currently,
drivers only) into the building context, while the latter
has everything that defines the bootstrap of a x86 CPU.

This commit also fixes platform/galileo/ so it includes the
correct makefile - Makefile.x86_quarkX1000. Galileo uses
a Quark X1000 SoC which is not an IBM Generic PC-like CPU,
but it does provide most of a PCs peripherals through
its "Legacy Bridge". Thus, it makes sense that QuarkX1000's
Makefile includes code from the legacy_pc x86 cpu.
2015-12-21 08:06:14 -02:00