One of the nice ideas behind paravirt is that CONFIG_XEN=y can be included
in a standard configuration and be no worse for native booting than as a
Xen guest. The glibc feature that supports the vDSO "nosegneg" note is
designed specifically to make this easy. You just have to flip one bit at
boot time. This patch makes Xen flip the bit, so a CONFIG_XEN=y kernel on
bare hardware does not make glibc use the less-optimized library builds.
Signed-off-by: Roland McGrath <roland@redhat.com>
Acked-by: Jeremy Fitzhardinge <jeremy@xensource.com>
Cc: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
arch/i386/xen/xen-asm.S defines some small pieces of code which are
used to implement a few paravirt_ops. They're designed so they can be
used either in-place, or be inline patched into their callsites if
there's enough space.
Some of those operations need to make calls out (specifically, if you
re-enable events [interrupts], and there's a pending event at that
time). These calls need the call instruction to be relocated if the
code is patched inline. In this case xen_foo_reloc is a
section-relative symbol which points to xen_foo's required relocation.
Other operations have no need of a relocation, and so their
corresponding xen_bar_reloc is absolute 0. These are the cases which
are triggering the warning.
This patch adds those symbols to the list of safe abs symbols.
Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com>
Cc: Adrian Bunk <bunk@stusta.de>
This patch hooks the new x86 setup code into the Makefile machinery. It
also adapts boot/tools/build.c to a two-file (as opposed to three-file)
universe, and simplifies it substantially.
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The relocatable kernel code needs a scratch field for the decompressor
to determine its own location. It was using a location inside
struct screen_info; reserve a free location and document it as scratch
instead.
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
inflate_fixed and huft_build together use around 2.7k of stack. When
using 4k stacks, I saw stack overflows from interrupts arriving while
unpacking the root initrd:
do_IRQ: stack overflow: 384
[<c0106b64>] show_trace_log_lvl+0x1a/0x30
[<c01075e6>] show_trace+0x12/0x14
[<c010763f>] dump_stack+0x16/0x18
[<c0107ca4>] do_IRQ+0x6d/0xd9
[<c010202b>] xen_evtchn_do_upcall+0x6e/0xa2
[<c0106781>] xen_hypervisor_callback+0x25/0x2c
[<c010116c>] xen_restore_fl+0x27/0x29
[<c0330f63>] _spin_unlock_irqrestore+0x4a/0x50
[<c0117aab>] change_page_attr+0x577/0x584
[<c0117b45>] kernel_map_pages+0x8d/0xb4
[<c016a314>] cache_alloc_refill+0x53f/0x632
[<c016a6c2>] __kmalloc+0xc1/0x10d
[<c0463d34>] malloc+0x10/0x12
[<c04641c1>] huft_build+0x2a7/0x5fa
[<c04645a5>] inflate_fixed+0x91/0x136
[<c04657e2>] unpack_to_rootfs+0x5f2/0x8c1
[<c0465acf>] populate_rootfs+0x1e/0xe4
(This was under Xen, but there's no reason it couldn't happen on bare
hardware.)
This patch mallocs the local variables, thereby reducing the stack
usage to sane levels.
Also, up the heap size for the kernel decompressor to deal with the
extra allocation.
Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Cc: Tim Yamin <plasmaroo@gentoo.org>
Cc: Andi Kleen <ak@suse.de>
Cc: Matt Mackall <mpm@selenic.com>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: Ian Molton <spyro@f2s.com>
Change the explicit code in the relocs.c file to use ARRAY_SIZE()
and add a definition of ARRAY_SIZE() since this is a userspace program
and wouldn't include kernel.h.
Signed-off-by: Robert P. J. Day <rpjday@mindspring.com>
Signed-off-by: Adrian Bunk <bunk@stusta.de>
i386 boot/compressed/relocs checks for absolute symbols and warns about
unexpected ones. If you build with modversions, you get ~2500 warnings
about __crc_<symbol>. These suckers are really absolute symbols - we
do _not_ want to modify them on relocation.
They are generated by genksyms - EXPORT_... generates a weak alias, then
genksyms produces an ld script with __crc_<symbol> = <checksum> and it's
fed to ld to produce the final object file. Their only use is to match
kernel and module at modprobe time; they _must_ be absolute.
boot/compressed/relocs has a whitelist of known absolute symbols, but
it doesn't know about __crc_... stuff. As the result, we get shitloads
of false positives on any ld(1) version.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Commit 968de4f026 ("i386: Relocatable
kernel support") caused problems for people with old binutils versions
that didn't mark ".text.*" sections automatically allocated.
So we should use .section command to specifically mark .text.head
section as AX (allocatable and executable) to solve the problem.
This should be unnecessary with binutils 2.15 and later, which is
already three years old, but it doesn't hurt supporting older toolchains
where possible.
Signed-off-by: Vivek Goyal <vgoyal@in.ibm.com>
Acked-by: Jean Delvare <khali@linux-fr.org>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Due to the changes to make the kernel relocateable a new file is created
during the build process.
[jirislaby@gmail.com: The .gitigonre was intended to be in arch/ subtree]
Signed-off-by: Thomas Meyer <thomas@m3y3r.de>
Signed-off-by: Jiri Slaby <jirislaby@gmail.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Create a paravirt.h header for all the critical operations which need to be
replaced with hypervisor calls, and include that instead of defining native
operations, when CONFIG_PARAVIRT.
This patch does the dumbest possible replacement of paravirtualized
instructions: calls through a "paravirt_ops" structure. Currently these are
function implementations of native hardware: hypervisors will override the ops
structure with their own variants.
All the pv-ops functions are declared "fastcall" so that a specific
register-based ABI is used, to make inlining assember easier.
And:
+From: Andy Whitcroft <apw@shadowen.org>
The paravirt ops introduce a 'weak' attribute onto memory_setup().
Code ordering leads to the following warnings on x86:
arch/i386/kernel/setup.c:651: warning: weak declaration of
`memory_setup' after first use results in unspecified behavior
Move memory_setup() to avoid this.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Chris Wright <chrisw@sous-sol.org>
Signed-off-by: Andi Kleen <ak@suse.de>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Cc: Zachary Amsden <zach@vmware.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Andy Whitcroft <apw@shadowen.org>
o Now CONFIG_PHYSICAL_START is being replaced with CONFIG_PHYSICAL_ALIGN.
Hardcoding the kernel physical start value creates a problem in relocatable
kernel context due to boot loader limitations. For ex, if somebody
compiles a relocatable kernel to be run from address 4MB, but this kernel
will run from location 1MB as grub loads the kernel at physical address
1MB. Kernel thinks that I am a relocatable kernel and I should run from
the address I have been loaded at. So somebody wanting to run kernel
from 4MB alignment location (for improved performance regions) can't do
that.
o Hence, Eric proposed that probably CONFIG_PHYSICAL_ALIGN will make
more sense in relocatable kernel context. At run time kernel will move
itself to a physical addr location which meets user specified alignment
restrictions.
Signed-off-by: Vivek Goyal <vgoyal@in.ibm.com>
Signed-off-by: Andi Kleen <ak@suse.de>
o Relocations generated w.r.t absolute symbols are not processed as by
definition, absolute symbols are not to be relocated. Explicitly warn
user about absolutions relocations present at compile time.
o These relocations get introduced either due to linker optimizations or
some programming oversights.
o Also create a list of symbols which have been audited to be safe and
don't emit warnings for these.
Signed-off-by: Vivek Goyal <vgoyal@in.ibm.com>
Signed-off-by: Andi Kleen <ak@suse.de>
This patch modifies the i386 kernel so that if CONFIG_RELOCATABLE is
selected it will be able to be loaded at any 4K aligned address below
1G. The technique used is to compile the decompressor with -fPIC and
modify it so the decompressor is fully relocatable. For the main
kernel relocations are generated. Resulting in a kernel that is relocatable
with no runtime overhead and no need to modify the source code.
A reserved 32bit word in the parameters has been assigned
to serve as a stack so we figure out where are running.
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Vivek Goyal <vgoyal@in.ibm.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Defining __PHYSICAL_START and __KERNEL_START in asm-i386/page.h works but
it triggers a full kernel rebuild for the silliest of reasons. This
modifies the users to directly use CONFIG_PHYSICAL_START and linux/config.h
which prevents the full rebuild problem, which makes the code much
more maintainer and hopefully user friendly.
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Vivek Goyal <vgoyal@in.ibm.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Clean up arch/{i386,x86_64}/boot/compressed/misc.c a bit to reduce their
differences. Should have zero effect on code generation.
Signed-off-by: Carl-Daniel Hailfinger <c-d.hailfinger.devel.2006@gmx.net>
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This makes it possible for boot code to use screen_info without dragging in
all of tty.h.
Signed-off-by: Brian Gerst <bgerst@didntduck.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Remove some of the unnecessary differences between arch/i386 and
arch/x86_64. This patch fixes more whitespace issues, some miscellaneous
typos, a wrong URL and a factually incorrect statement about the current
boot sector code.
Signed-off-by: Domen Puncer <domen@coderock.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
For one kernel to report a crash another kernel has created we need
to have 2 kernels loaded simultaneously in memory. To accomplish this
the two kernels need to built to run at different physical addresses.
This patch adds the CONFIG_PHYSICAL_START option to the x86 kernel
so we can do just that. You need to know what you are doing and
the ramifications are before changing this value, and most users
won't care so I have made it depend on CONFIG_EMBEDDED
bzImage kernels will work and run at a different address when compiled
with this option but they will still load at 1MB. If you need a kernel
loaded at a different address as well you need to boot a vmlinux.
Signed-off-by: Eric Biederman <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.
Let it rip!
