fix off by one error in max call depth check
and add a test
Fixes: f4d7e40a5b ("bpf: introduce function calls (verification)")
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Instead of computing max stack depth for current call chain
during the main verifier pass track stack depth of each
function independently and after do_check() is done do
another pass over all instructions analyzing depth
of all possible call stacks.
Fixes: f4d7e40a5b ("bpf: introduce function calls (verification)")
Reported-by: Jann Horn <jannh@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
This checks that it is not possible to bypass the total stack size check in
update_stack_depth() by calling a function that uses a large amount of
stack memory *before* using a large amount of stack memory in the caller.
Currently, the first added testcase causes a rejection as expected, but
the second testcase is (AFAICS incorrectly) accepted:
[...]
#483/p calls: stack overflow using two frames (post-call access) FAIL
Unexpected success to load!
0: (85) call pc+2
caller:
R10=fp0,call_-1
callee:
frame1: R1=ctx(id=0,off=0,imm=0) R10=fp0,call_0
3: (72) *(u8 *)(r10 -300) = 0
4: (b7) r0 = 0
5: (95) exit
returning from callee:
frame1: R0_w=inv0 R1=ctx(id=0,off=0,imm=0) R10=fp0,call_0
to caller at 1:
R0_w=inv0 R10=fp0,call_-1
from 5 to 1: R0=inv0 R10=fp0,call_-1
1: (72) *(u8 *)(r10 -300) = 0
2: (95) exit
processed 6 insns, stack depth 300+300
[...]
Summary: 704 PASSED, 1 FAILED
AFAICS the JIT-generated code for the second testcase shows that this
really causes the stack pointer to be decremented by 300+300:
first function:
00000000 55 push rbp
00000001 4889E5 mov rbp,rsp
00000004 4881EC58010000 sub rsp,0x158
0000000B 4883ED28 sub rbp,byte +0x28
[...]
00000025 E89AB3AFE5 call 0xffffffffe5afb3c4
0000002A C685D4FEFFFF00 mov byte [rbp-0x12c],0x0
[...]
00000041 4883C528 add rbp,byte +0x28
00000045 C9 leave
00000046 C3 ret
second function:
00000000 55 push rbp
00000001 4889E5 mov rbp,rsp
00000004 4881EC58010000 sub rsp,0x158
0000000B 4883ED28 sub rbp,byte +0x28
[...]
00000025 C685D4FEFFFF00 mov byte [rbp-0x12c],0x0
[...]
0000003E 4883C528 add rbp,byte +0x28
00000042 C9 leave
00000043 C3 ret
Signed-off-by: Jann Horn <jannh@google.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Commit cc2b14d510 ("bpf: teach verifier to recognize zero initialized
stack") introduced a very relaxed check when comparing stacks of different
states, effectively returning a positive result in many cases where it
shouldn't.
This can create problems in cases such as this following C pseudocode:
long var;
long *x = bpf_map_lookup(...);
if (!x)
return;
if (*x != 0xbeef)
var = 0;
else
var = 1;
/* This is the key part, calling a helper causes an explored state
* to be saved with the information that "var" is on the stack as
* STACK_ZERO, since the helper is first met by the verifier after
* the "var = 0" assignment. This state will however be wrongly used
* also for the "var = 1" case, so the verifier assumes "var" is always
* 0 and will replace the NULL assignment with nops, because the
* search pruning prevents it from exploring the faulty branch.
*/
bpf_ktime_get_ns();
if (var)
*(long *)0 = 0xbeef;
Fix the issue by making sure that the stack is fully explored before
returning a positive comparison result.
Also attach a couple tests that highlight the bad behavior. In the first
test, without this fix instructions 16 and 17 are replaced with nops
instead of being rejected by the verifier.
The second test, instead, allows a program to make a potentially illegal
read from the stack.
Fixes: cc2b14d510 ("bpf: teach verifier to recognize zero initialized stack")
Signed-off-by: Gianluca Borello <g.borello@gmail.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Modelled strongly upon the arm64 implementation.
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
The default rlimit RLIMIT_MEMLOCK is 64KB. In certain cases,
e.g. in a test machine mimicking our production system, this test may
fail due to unable to charge the required memory for prog load:
$ ./test_dev_cgroup
libbpf: load bpf program failed: Operation not permitted
libbpf: failed to load program 'cgroup/dev'
libbpf: failed to load object './dev_cgroup.o'
Failed to load DEV_CGROUP program
...
Changing the default rlimit RLIMIT_MEMLOCK to unlimited
makes the test pass.
This patch also fixed a problem where when bpf_prog_load fails,
cleanup_cgroup_environment() should not be called since
setup_cgroup_environment() has not been invoked. Otherwise,
the following confusing message will appear:
...
(/home/yhs/local/linux/tools/testing/selftests/bpf/cgroup_helpers.c:95:
errno: No such file or directory) Opening Cgroup Procs: /mnt/cgroup.procs
...
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Daniel Borkmann says:
====================
This work adds correlation of maps and calls into the bpftool
xlated dump in order to help debugging and introspection of
loaded BPF progs. First patch makes kallsyms work on subprogs
with bpf calls, and second implements the actual correlation.
Details and example output can be found in the 2nd patch.
====================
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Right now kallsyms handling is not working with JITed subprogs.
The reason is that when in 1c2a088a66 ("bpf: x64: add JIT support
for multi-function programs") in jit_subprogs() they are passed
to bpf_prog_kallsyms_add(), then their prog type is 0, which BPF
core will think it's a cBPF program as only cBPF programs have a
0 type. Thus, they need to inherit the type from the main prog.
Once that is fixed, they are indeed added to the BPF kallsyms
infra, but their tag is 0. Therefore, since intention is to add
them as bpf_prog_F_<tag>, we need to pass them to bpf_prog_calc_tag()
first. And once this is resolved, there is a use-after-free on
prog cleanup: we remove the kallsyms entry from the main prog,
later walk all subprogs and call bpf_jit_free() on them. However,
the kallsyms linkage was never released on them. Thus, do that
for all subprogs right in __bpf_prog_put() when refcount hits 0.
Fixes: 1c2a088a66 ("bpf: x64: add JIT support for multi-function programs")
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
These elf object pieces are of type Elf64_Xword and therefore could be
"long long" on some builds.
Cast to "long long" and use printf format %lld to deal with this since
we are building with -Werror=format.
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
The tools/testing/selftests/bpf test program
test_dev_cgroup fails with the following error
when compiled with llvm 6.0. (I did not try
with earlier versions.)
libbpf: load bpf program failed: Permission denied
libbpf: -- BEGIN DUMP LOG ---
libbpf:
0: (61) r2 = *(u32 *)(r1 +4)
1: (b7) r0 = 0
2: (55) if r2 != 0x1 goto pc+8
R0=inv0 R1=ctx(id=0,off=0,imm=0) R2=inv1 R10=fp0
3: (69) r2 = *(u16 *)(r1 +0)
invalid bpf_context access off=0 size=2
...
The culprit is the following statement in dev_cgroup.c:
short type = ctx->access_type & 0xFFFF;
This code is typical as the ctx->access_type is assigned
as below in kernel/bpf/cgroup.c:
struct bpf_cgroup_dev_ctx ctx = {
.access_type = (access << 16) | dev_type,
.major = major,
.minor = minor,
};
The compiler converts it to u16 access while
the verifier cgroup_dev_is_valid_access rejects
any non u32 access.
This patch permits the field access_type to be accessible
with type u16 and u8 as well.
Signed-off-by: Yonghong Song <yhs@fb.com>
Tested-by: Roman Gushchin <guro@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
The function xdp_do_generic_redirect_map() is only used in this file, so
make it static.
Clean up sparse warning:
net/core/filter.c:2687:5: warning: no previous prototype
for 'xdp_do_generic_redirect_map' [-Wmissing-prototypes]
Signed-off-by: Xiongwei Song <sxwjean@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
BPF offload tests (test_offload.py) will require netdevsim
to be built, add it to config.
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: Quentin Monnet <quentin.monnet@netronome.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
fix the following issue:
arch/arm64/net/bpf_jit_comp.c: In function 'bpf_int_jit_compile':
arch/arm64/net/bpf_jit_comp.c:982:18: error: 'image_size' may be used
uninitialized in this function [-Werror=maybe-uninitialized]
Fixes: db496944fd ("bpf: arm64: add JIT support for multi-function programs")
Reported-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Function skip_callee is local to the source and does not need to
be in global scope, so make it static. Also return NULL rather than 0.
Cleans up two sparse warnings:
symbol 'skip_callee' was not declared. Should it be static?
Using plain integer as NULL pointer
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Trivial fix to spelling mistake in error message text.
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Simplify PCIe Completion Timeout setting by using the
pcie_capability_clear_and_set_word() interface. No functional change
intended.
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
William Tu says:
====================
net: erspan: a couple fixes
Haishuang Yan reports a couple of issues (wrong return value,
pskb_may_pull) on erspan V1. Since erspan V2 is in net-next,
this series fix the similar issues on v2.
====================
Signed-off-by: David S. Miller <davem@davemloft.net>
pskb_may_pull() can change skb->data, so we need to re-load pkt_md
and ershdr at the right place.
Fixes: 94d7d8f292 ("ip6_gre: add erspan v2 support")
Fixes: f551c91de2 ("net: erspan: introduce erspan v2 for ip_gre")
Signed-off-by: William Tu <u9012063@gmail.com>
Cc: Haishuang Yan <yanhaishuang@cmss.chinamobile.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
If pskb_may_pull return failed, return PACKET_REJECT
instead of -ENOMEM.
Fixes: 94d7d8f292 ("ip6_gre: add erspan v2 support")
Fixes: f551c91de2 ("net: erspan: introduce erspan v2 for ip_gre")
Signed-off-by: William Tu <u9012063@gmail.com>
Cc: Haishuang Yan <yanhaishuang@cmss.chinamobile.com>
Acked-by: Haishuang Yan <yanhaishuang@cmss.chinamobile.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Russell King says:
====================
More SFP/phylink fixes
This series fixes a few more bits with sfp/phylink, particularly
confusion with the right way to test for the RTNL mutex being
held, a change in 2016 to the mdiobus_scan() behaviour that wasn't
noticed, and a fix for reading module EEPROMs.
====================
Signed-off-by: David S. Miller <davem@davemloft.net>
Use ASSERT_RTNL() rather than WARN_ON(!lockdep_rtnl_is_held()) which
stops working when lockdep fires, and we end up with lots of warnings.
Fixes: 9525ae8395 ("phylink: add phylink infrastructure")
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>
The EEPROM reading was trying to read from the second EEPROM address
if we requested the last byte from the SFF8079 EEPROM, which caused a
failure when the second EEPROM is not present. Discovered with a
S-RJ01 SFP module. Fix this.
Fixes: 7397005545 ("sfp: add SFP module support")
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>
The detection of a PHY changed in commit e98a3aabf8 ("mdio_bus: don't
return NULL from mdiobus_scan()") which now causes sfp to print an
error message. Update for this change.
Fixes: 7397005545 ("sfp: add SFP module support")
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>
The current HNCDSC handler takes the status flag from the AEN packet and
will update or change the current channel based on this flag and the
current channel status.
However the flag from the HNCDSC packet merely represents the host link
state. While the state of the host interface is potentially interesting
information it should not affect the state of the NCSI link. Indeed the
NCSI specification makes no mention of any recommended action related to
the host network controller driver state.
Update the HNCDSC handler to record the host network driver status but
take no other action.
Signed-off-by: Samuel Mendoza-Jonas <sam@mendozajonas.com>
Acked-by: Jeremy Kerr <jk@ozlabs.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Jerome Brunet says:
====================
net: phy: meson-gxl: clean-up and improvements
This patchset adds defines for the control registers and helpers to access
the banked registers. The goal being to make it easier to understand what
the driver actually does.
Then CONFIG_A6 settings is removed since this statement was without effect
Finally interrupt support is added, speeding things up a little
This series has been tested on the libretech-cc and khadas VIM
Changes since v2 [0]:
Drop LPA corruption fix which has been merged through net. Apart from this,
series remains the same.
[0]: https://lkml.kernel.org/r/20171207142715.32578-1-jbrunet@baylibre.com
====================
Signed-off-by: David S. Miller <davem@davemloft.net>
Following previous changes, join the other authors of this driver and
take the blame with them
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Jerome Brunet <jbrunet@baylibre.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Enable interrupt support in meson-gxl PHY driver
Signed-off-by: Jerome Brunet <jbrunet@baylibre.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
The PHY performs just as well when left in its default configuration and
it makes senses because this poke gets reset just after init.
According to the documentation, all registers in the Analog/DSP bank are
reset when there is a mode switch from 10BT to 100BT. The bank is also
reset on power down and soft reset, so we will never see the value which
may have been set by the bootloader.
In the end, we have used the default configuration so far and there is no
reason to change now. Remove CONFIG_A6 poke to make this clear.
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Jerome Brunet <jbrunet@baylibre.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Use the generic init function to populate some of the phydev
structure fields
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Jerome Brunet <jbrunet@baylibre.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Add read and write helpers to manipulate banked registers on this PHY
This helps clarify the settings applied to these registers and what the
driver actually does
Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Signed-off-by: Jerome Brunet <jbrunet@baylibre.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Define registers and bits in meson-gxl PHY driver to make a bit
more human friendly. No functional change.
Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Signed-off-by: Jerome Brunet <jbrunet@baylibre.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Always check phy_write return values. Better to be safe than sorry
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Jerome Brunet <jbrunet@baylibre.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Edward Cree says:
====================
sfc: Initial X2000-series (Medford2) support
Basic PCI-level changes to support X2000-series NICs.
Also fix unexpected-PTP-event log messages, since the timestamp format has
been changed in these NICs and that causes us to fail to probe PTP (but we
still get the PPS events).
====================
Signed-off-by: David S. Miller <davem@davemloft.net>
The timer mode register now has a separate field for the reload value.
Since we always use this timer with the reload (for interrupt moderation)
we set this to the same as the initial value.
Previous hardware ignores this field, so we can safely set these bits
on all hardware that uses this register.
Signed-off-by: Edward Cree <ecree@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
The RX_L4_CLASS field has shrunk from 3 bits to 2 bits. The upper
bit was never used in previous hardware, so we can use the new
definition throughout.
The TSO OUTER_IPID field was previously spelt differently from the
external definitions.
Signed-off-by: Edward Cree <ecree@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Log a message if PTP probing fails; if we then, unexpectedly, get PTP
events, only log a message for the first one on each device.
Signed-off-by: Edward Cree <ecree@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Medford2 can also have 16k or 64k VI stride. This is reported by MCDI in
GET_CAPABILITIES, which fortunately is called before the driver does
anything sensitive to the VI stride (such as accessing or even allocating
VIs past the zeroth).
Signed-off-by: Edward Cree <ecree@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Support using BAR 0 on SFC9250, even though the driver doesn't bind to such
devices yet.
Signed-off-by: Edward Cree <ecree@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Daniel Borkmann says:
====================
pull-request: bpf-next 2017-12-18
The following pull-request contains BPF updates for your *net-next* tree.
The main changes are:
1) Allow arbitrary function calls from one BPF function to another BPF function.
As of today when writing BPF programs, __always_inline had to be used in
the BPF C programs for all functions, unnecessarily causing LLVM to inflate
code size. Handle this more naturally with support for BPF to BPF calls
such that this __always_inline restriction can be overcome. As a result,
it allows for better optimized code and finally enables to introduce core
BPF libraries in the future that can be reused out of different projects.
x86 and arm64 JIT support was added as well, from Alexei.
2) Add infrastructure for tagging functions as error injectable and allow for
BPF to return arbitrary error values when BPF is attached via kprobes on
those. This way of injecting errors generically eases testing and debugging
without having to recompile or restart the kernel. Tags for opting-in for
this facility are added with BPF_ALLOW_ERROR_INJECTION(), from Josef.
3) For BPF offload via nfp JIT, add support for bpf_xdp_adjust_head() helper
call for XDP programs. First part of this work adds handling of BPF
capabilities included in the firmware, and the later patches add support
to the nfp verifier part and JIT as well as some small optimizations,
from Jakub.
4) The bpftool now also gets support for basic cgroup BPF operations such
as attaching, detaching and listing current BPF programs. As a requirement
for the attach part, bpftool can now also load object files through
'bpftool prog load'. This reuses libbpf which we have in the kernel tree
as well. bpftool-cgroup man page is added along with it, from Roman.
5) Back then commit e87c6bc385 ("bpf: permit multiple bpf attachments for
a single perf event") added support for attaching multiple BPF programs
to a single perf event. Given they are configured through perf's ioctl()
interface, the interface has been extended with a PERF_EVENT_IOC_QUERY_BPF
command in this work in order to return an array of one or multiple BPF
prog ids that are currently attached, from Yonghong.
6) Various minor fixes and cleanups to the bpftool's Makefile as well
as a new 'uninstall' and 'doc-uninstall' target for removing bpftool
itself or prior installed documentation related to it, from Quentin.
7) Add CONFIG_CGROUP_BPF=y to the BPF kernel selftest config file which is
required for the test_dev_cgroup test case to run, from Naresh.
8) Fix reporting of XDP prog_flags for nfp driver, from Jakub.
9) Fix libbpf's exit code from the Makefile when libelf was not found in
the system, also from Jakub.
====================
Signed-off-by: David S. Miller <davem@davemloft.net>
Things got moved around between the original bpf_override_return patches
and the final version, and now the ftrace kprobe dispatcher assumes if
you modified the ip that you also enabled preemption. Make a comment of
this and enable preemption, this fixes the lockdep splat that happened
when using this feature.
Fixes: 9802d86585 ("bpf: add a bpf_override_function helper")
Signed-off-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
netdev_bpf.flags is the input member for installing the program.
netdev_bpf.prog_flags is the output member for querying. Set
the correct one on query.
Fixes: 92f0292b35 ("net: xdp: report flags program was installed with on query")
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: Quentin Monnet <quentin.monnet@netronome.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
/bin/sh's exit does not recognize -1 as a number, leading to
the following error message:
/bin/sh: 1: exit: Illegal number: -1
Use 1 as the exit code.
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: Quentin Monnet <quentin.monnet@netronome.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Alexei Starovoitov says:
====================
First of all huge thank you to Daniel, John, Jakub, Edward and others who
reviewed multiple iterations of this patch set over the last many months
and to Dave and others who gave critical feedback during netconf/netdev.
The patch is solid enough and we thought through numerous corner cases,
but it's not the end. More followups with code reorg and features to follow.
TLDR: Allow arbitrary function calls from bpf function to another bpf function.
Since the beginning of bpf all bpf programs were represented as a single function
and program authors were forced to use always_inline for all functions
in their C code. That was causing llvm to unnecessary inflate the code size
and forcing developers to move code to header files with little code reuse.
With a bit of additional complexity teach verifier to recognize
arbitrary function calls from one bpf function to another as long as
all of functions are presented to the verifier as a single bpf program.
Extended program layout:
..
r1 = .. // arg1
r2 = .. // arg2
call pc+1 // function call pc-relative
exit
.. = r1 // access arg1
.. = r2 // access arg2
..
call pc+20 // second level of function call
...
It allows for better optimized code and finally allows to introduce
the core bpf libraries that can be reused in different projects,
since programs are no longer limited by single elf file.
With function calls bpf can be compiled into multiple .o files.
This patch is the first step. It detects programs that contain
multiple functions and checks that calls between them are valid.
It splits the sequence of bpf instructions (one program) into a set
of bpf functions that call each other. Calls to only known
functions are allowed. Since all functions are presented to
the verifier at once conceptually it is 'static linking'.
Future plans:
- introduce BPF_PROG_TYPE_LIBRARY and allow a set of bpf functions
to be loaded into the kernel that can be later linked to other
programs with concrete program types. Aka 'dynamic linking'.
- introduce function pointer type and indirect calls to allow
bpf functions call other dynamically loaded bpf functions while
the caller bpf function is already executing. Aka 'runtime linking'.
This will be more generic and more flexible alternative
to bpf_tail_calls.
FAQ:
Q: Interpreter and JIT changes mean that new instruction is introduced ?
A: No. The call instruction technically stays the same. Now it can call
both kernel helpers and other bpf functions.
Calling convention stays the same as well.
From uapi point of view the call insn got new 'relocation' BPF_PSEUDO_CALL
similar to BPF_PSEUDO_MAP_FD 'relocation' of bpf_ldimm64 insn.
Q: What had to change on LLVM side?
A: Trivial LLVM patch to allow calls was applied to upcoming 6.0 release:
https://reviews.llvm.org/rL318614
with few bugfixes as well.
Make sure to build the latest llvm to have bpf_call support.
More details in the patches.
====================
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Add some additional checks for few more corner cases.
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
similar to x64 add support for bpf-to-bpf calls.
When program has calls to in-kernel helpers the target call offset
is known at JIT time and arm64 architecture needs 2 passes.
With bpf-to-bpf calls the dynamically allocated function start
is unknown until all functions of the program are JITed.
Therefore (just like x64) arm64 JIT needs one extra pass over
the program to emit correct call offsets.
Implementation detail:
Avoid being too clever in 64-bit immediate moves and
always use 4 instructions (instead of 3-4 depending on the address)
to make sure only one extra pass is needed.
If some future optimization would make it worth while to optimize
'call 64-bit imm' further, the JIT would need to do 4 passes
over the program instead of 3 as in this patch.
For typical bpf program address the mov needs 3 or 4 insns,
so unconditional 4 insns to save extra pass is a worthy trade off
at this state of JIT.
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Typical JIT does several passes over bpf instructions to
compute total size and relative offsets of jumps and calls.
With multitple bpf functions calling each other all relative calls
will have invalid offsets intially therefore we need to additional
last pass over the program to emit calls with correct offsets.
For example in case of three bpf functions:
main:
call foo
call bpf_map_lookup
exit
foo:
call bar
exit
bar:
exit
We will call bpf_int_jit_compile() indepedently for main(), foo() and bar()
x64 JIT typically does 4-5 passes to converge.
After these initial passes the image for these 3 functions
will be good except call targets, since start addresses of
foo() and bar() are unknown when we were JITing main()
(note that call bpf_map_lookup will be resolved properly
during initial passes).
Once start addresses of 3 functions are known we patch
call_insn->imm to point to right functions and call
bpf_int_jit_compile() again which needs only one pass.
Additional safety checks are done to make sure this
last pass doesn't produce image that is larger or smaller
than previous pass.
When constant blinding is on it's applied to all functions
at the first pass, since doing it once again at the last
pass can change size of the JITed code.
Tested on x64 and arm64 hw with JIT on/off, blinding on/off.
x64 jits bpf-to-bpf calls correctly while arm64 falls back to interpreter.
All other JITs that support normal BPF_CALL will behave the same way
since bpf-to-bpf call is equivalent to bpf-to-kernel call from
JITs point of view.
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
global bpf_jit_enable variable is tested multiple times in JITs,
blinding and verifier core. The malicious root can try to toggle
it while loading the programs. This race condition was accounted
for and there should be no issues, but it's safer to avoid
this race condition.
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
