lib/test_bpf: Add tests for unsigned BPF_JGT

Unsigned Jump-if-Greater-Than.

Cc: Alexei Starovoitov <ast@fb.com>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: "David S. Mill

lib/test_bpf: Add tests for unsigned BPF_JGT

Unsigned Jump-if-Greater-Than.

Cc: Alexei Starovoitov <ast@fb.com>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Paul Mackerras <paulus@samba.org>
Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

show more ...

lib/test_bpf: Fix JMP_JSET tests

JMP_JSET tests incorrectly used BPF_JNE. Fix the same.

Cc: Alexei Starovoitov <ast@fb.com>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: "D

lib/test_bpf: Fix JMP_JSET tests

JMP_JSET tests incorrectly used BPF_JNE. Fix the same.

Cc: Alexei Starovoitov <ast@fb.com>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Paul Mackerras <paulus@samba.org>
Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

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bpf, test: add couple of test cases

Add couple of test cases for interpreter but also JITs, f.e. to test that
when imm32 moves are being done, upper 32bits of the regs are being zero

bpf, test: add couple of test cases

Add couple of test cases for interpreter but also JITs, f.e. to test that
when imm32 moves are being done, upper 32bits of the regs are being zero
extended.

Without JIT:

[...]
[ 1114.129301] test_bpf: #43 MOV REG64 jited:0 128 PASS
[ 1114.130626] test_bpf: #44 MOV REG32 jited:0 139 PASS
[ 1114.132055] test_bpf: #45 LD IMM64 jited:0 124 PASS
[...]

With JIT (generated code can as usual be nicely verified with the help of
bpf_jit_disasm tool):

[...]
[ 1062.726782] test_bpf: #43 MOV REG64 jited:1 6 PASS
[ 1062.726890] test_bpf: #44 MOV REG32 jited:1 6 PASS
[ 1062.726993] test_bpf: #45 LD IMM64 jited:1 6 PASS
[...]

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

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bpf: add mod default A and X test cases

When running "mod X" operation, if X is 0 the filter has to be halt.
Add new test cases to cover A = A mod X if X is 0, and A = A mod 1.

bpf: add mod default A and X test cases

When running "mod X" operation, if X is 0 the filter has to be halt.
Add new test cases to cover A = A mod X if X is 0, and A = A mod 1.

CC: Xi Wang <xi.wang@gmail.com>
CC: Zi Shen Lim <zlim.lnx@gmail.com>
Signed-off-by: Yang Shi <yang.shi@linaro.org>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Zi Shen Lim <zlim.lnx@gmail.com>
Acked-by: Xi Wang <xi.wang@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

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test_bpf: add tests checking that JIT/interpreter sets A and X to 0.

It is mandatory for the JIT or interpreter to reset the A and X
registers to 0 before running the filter. Check that

test_bpf: add tests checking that JIT/interpreter sets A and X to 0.

It is mandatory for the JIT or interpreter to reset the A and X
registers to 0 before running the filter. Check that it is the case on
various ALU and JMP instructions.

Signed-off-by: Nicolas Schichan <nschichan@freebox.fr>
Acked-by: Alexei Starovoitov <ast@plumgrid.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

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test_bpf: add more tests for LD_ABS and LD_IND.

This exerces the LD_ABS and LD_IND instructions for various sizes and
alignments. This also checks that X when used as an offset to a

test_bpf: add more tests for LD_ABS and LD_IND.

This exerces the LD_ABS and LD_IND instructions for various sizes and
alignments. This also checks that X when used as an offset to a
BPF_IND instruction first in a filter is correctly set to 0.

Signed-off-by: Nicolas Schichan <nschichan@freebox.fr>
Acked-by: Alexei Starovoitov <ast@plumgrid.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

show more ...

test_bpf: add module parameters to filter the tests to run.

When developping on the interpreter or a particular JIT, it can be
interesting to restrict the tests list to a specific test o

test_bpf: add module parameters to filter the tests to run.

When developping on the interpreter or a particular JIT, it can be
interesting to restrict the tests list to a specific test or a
particular range of tests.

This patch adds the following module parameters to the test_bpf module:

* test_name=<string>: only the specified named test will be run.

* test_id=<number>: only the test with the specified id will be run
(see the output of test_bpf without parameters to get the test id).

* test_range=<number>,<number>: only the tests within IDs in the
specified id range are run (see the output of test_bpf without
parameters to get the test ids).

Any invalid range, test id or test name will result in -EINVAL being
returned and no tests being run.

Signed-off-by: Nicolas Schichan <nschichan@freebox.fr>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@plumgrid.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

show more ...

test_bpf: test LD_ABS and LD_IND instructions on fragmented skbs.

These new tests exercise various load sizes and offsets crossing the
head/fragment boundary.

Signed-off-by: Nic

test_bpf: test LD_ABS and LD_IND instructions on fragmented skbs.

These new tests exercise various load sizes and offsets crossing the
head/fragment boundary.

Signed-off-by: Nicolas Schichan <nschichan@freebox.fr>
Acked-by: Alexei Starovoitov <ast@plumgrid.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

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test_bpf: allow tests to specify an skb fragment.

This introduce a new test->aux flag (FLAG_SKB_FRAG) to tell the
populate_skb() function to add a fragment to the test skb containing

test_bpf: allow tests to specify an skb fragment.

This introduce a new test->aux flag (FLAG_SKB_FRAG) to tell the
populate_skb() function to add a fragment to the test skb containing
the data specified in test->frag_data).

Signed-off-by: Nicolas Schichan <nschichan@freebox.fr>
Acked-by: Alexei Starovoitov <ast@plumgrid.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

show more ...

test_bpf: avoid oopsing the kernel when generate_test_data() fails.

Signed-off-by: Nicolas Schichan <nschichan@freebox.fr>
Acked-by: Alexei Starovoitov <ast@plumgrid.com>
Acked-by: D

test_bpf: avoid oopsing the kernel when generate_test_data() fails.

Signed-off-by: Nicolas Schichan <nschichan@freebox.fr>
Acked-by: Alexei Starovoitov <ast@plumgrid.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

show more ...

test_bpf: assign type to native eBPF test cases

As JITs start to perform optimizations whether to clear A and X on eBPF
programs in the prologue, we should actually assign a program type

test_bpf: assign type to native eBPF test cases

As JITs start to perform optimizations whether to clear A and X on eBPF
programs in the prologue, we should actually assign a program type to the
native eBPF test cases. It doesn't really matter which program type, as
these instructions don't go through the verifier, but it needs to be a
type != BPF_PROG_TYPE_UNSPEC. This reflects eBPF programs loaded via bpf(2)
system call (!= type unspec) vs. classic BPF to eBPF migrations (== type
unspec).

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Cc: Michael Holzheu <holzheu@linux.vnet.ibm.com>
Acked-by: Alexei Starovoitov <ast@plumgrid.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

show more ...

test_bpf: add bpf_skb_vlan_push/pop() tests

improve accuracy of timing in test_bpf and add two stress tests:
- {skb->data[0], get_smp_processor_id} repeated 2k times
- {skb->data[0],

test_bpf: add bpf_skb_vlan_push/pop() tests

improve accuracy of timing in test_bpf and add two stress tests:
- {skb->data[0], get_smp_processor_id} repeated 2k times
- {skb->data[0], vlan_push} x 68 followed by {skb->data[0], vlan_pop} x 68

1st test is useful to test performance of JIT implementation of BPF_LD_ABS
together with BPF_CALL instructions.
2nd test is stressing skb_vlan_push/pop logic together with skb->data access
via BPF_LD_ABS insn which checks that re-caching of skb->data is done correctly.

In order to call bpf_skb_vlan_push() from test_bpf.ko have to add
three export_symbol_gpl.

Signed-off-by: Alexei Starovoitov <ast@plumgrid.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

show more ...

test_bpf: extend tests for 32-bit endianness conversion

Currently "ALU_END_FROM_BE 32" and "ALU_END_FROM_LE 32" do not test if
the upper bits of the result are zeros (the arm64 JIT had s

test_bpf: extend tests for 32-bit endianness conversion

Currently "ALU_END_FROM_BE 32" and "ALU_END_FROM_LE 32" do not test if
the upper bits of the result are zeros (the arm64 JIT had such bugs).
Extend the two tests to catch this.

Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@plumgrid.com>
Signed-off-by: Xi Wang <xi.wang@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

show more ...

test_bpf: add similarly conflicting jump test case only for classic

While 3b52960266a3 ("test_bpf: add more eBPF jump torture cases")
added the int3 bug test case only for eBPF, which ne

test_bpf: add similarly conflicting jump test case only for classic

While 3b52960266a3 ("test_bpf: add more eBPF jump torture cases")
added the int3 bug test case only for eBPF, which needs exactly 11
passes to converge, here's a version for classic BPF with 11 passes,
and one that would need 70 passes on x86_64 to actually converge for
being successfully JITed. Effectively, all jumps are being optimized
out resulting in a JIT image of just 89 bytes (from originally max
BPF insns), only returning K.

Might be useful as a receipe for folks wanting to craft a test case
when backporting the fix in commit 3f7352bf21f8 ("x86: bpf_jit: fix
compilation of large bpf programs") while not having eBPF. The 2nd
one is delegated to the interpreter as the last pass still results
in shrinking, in other words, this one won't be JITed on x86_64.

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@plumgrid.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

show more ...

test_bpf: add more eBPF jump torture cases

Add two more eBPF test cases for JITs, i.e. the second one revealed a
bug in the x86_64 JIT compiler, where only an int3 filled image from

test_bpf: add more eBPF jump torture cases

Add two more eBPF test cases for JITs, i.e. the second one revealed a
bug in the x86_64 JIT compiler, where only an int3 filled image from
the allocator was emitted and later wrongly set by the compiler as the
bpf_func program code since optimization pass boundary was surpassed
w/o actually emitting opcodes.

Interpreter:

[ 45.782892] test_bpf: #242 BPF_MAXINSNS: Very long jump backwards jited:0 11 PASS
[ 45.783062] test_bpf: #243 BPF_MAXINSNS: Edge hopping nuthouse jited:0 14705 PASS

After x86_64 JIT (fixed):

[ 80.495638] test_bpf: #242 BPF_MAXINSNS: Very long jump backwards jited:1 6 PASS
[ 80.495957] test_bpf: #243 BPF_MAXINSNS: Edge hopping nuthouse jited:1 17157 PASS

Reference: http://thread.gmane.org/gmane.linux.network/364729
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@plumgrid.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

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test_bpf: Add backward jump test case

Currently the testsuite does not have a test case with a backward jump.
The s390x JIT (kernel 4.0) had a bug in that area.
So add one new test c

test_bpf: Add backward jump test case

Currently the testsuite does not have a test case with a backward jump.
The s390x JIT (kernel 4.0) had a bug in that area.
So add one new test case for this now.

Signed-off-by: Michael Holzheu <holzheu@linux.vnet.ibm.com>
Signed-off-by: Alexei Starovoitov <ast@plumgrid.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

show more ...

test_bpf: fix sparse warnings

Fix several sparse warnings like:
lib/test_bpf.c:1824:25: sparse: constant 4294967295 is so big it is long
lib/test_bpf.c:1878:25: sparse: constant 0x00

test_bpf: fix sparse warnings

Fix several sparse warnings like:
lib/test_bpf.c:1824:25: sparse: constant 4294967295 is so big it is long
lib/test_bpf.c:1878:25: sparse: constant 0x0000ffffffff0000 is so big it is long

Fixes: cffc642d93f9 ("test_bpf: add 173 new testcases for eBPF")
Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Michael Holzheu <holzheu@linux.vnet.ibm.com>
Signed-off-by: Alexei Starovoitov <ast@plumgrid.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

show more ...

test_bpf: add tests related to BPF_MAXINSNS

Couple of torture test cases related to the bug fixed in 0b59d8806a31
("ARM: net: delegate filter to kernel interpreter when imm_offset()

test_bpf: add tests related to BPF_MAXINSNS

Couple of torture test cases related to the bug fixed in 0b59d8806a31
("ARM: net: delegate filter to kernel interpreter when imm_offset()
return value can't fit into 12bits.").

I've added a helper to allocate and fill the insn space. Output on
x86_64 from my laptop:

test_bpf: #233 BPF_MAXINSNS: Maximum possible literals jited:0 7 PASS
test_bpf: #234 BPF_MAXINSNS: Single literal jited:0 8 PASS
test_bpf: #235 BPF_MAXINSNS: Run/add until end jited:0 11553 PASS
test_bpf: #236 BPF_MAXINSNS: Too many instructions PASS
test_bpf: #237 BPF_MAXINSNS: Very long jump jited:0 9 PASS
test_bpf: #238 BPF_MAXINSNS: Ctx heavy transformations jited:0 20329 20398 PASS
test_bpf: #239 BPF_MAXINSNS: Call heavy transformations jited:0 32178 32475 PASS
test_bpf: #240 BPF_MAXINSNS: Jump heavy test jited:0 10518 PASS

test_bpf: #233 BPF_MAXINSNS: Maximum possible literals jited:1 4 PASS
test_bpf: #234 BPF_MAXINSNS: Single literal jited:1 4 PASS
test_bpf: #235 BPF_MAXINSNS: Run/add until end jited:1 1625 PASS
test_bpf: #236 BPF_MAXINSNS: Too many instructions PASS
test_bpf: #237 BPF_MAXINSNS: Very long jump jited:1 8 PASS
test_bpf: #238 BPF_MAXINSNS: Ctx heavy transformations jited:1 3301 3174 PASS
test_bpf: #239 BPF_MAXINSNS: Call heavy transformations jited:1 24107 23491 PASS
test_bpf: #240 BPF_MAXINSNS: Jump heavy test jited:1 8651 PASS

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Cc: Alexei Starovoitov <ast@plumgrid.com>
Cc: Nicolas Schichan <nschichan@freebox.fr>
Acked-by: Alexei Starovoitov <ast@plumgrid.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

show more ...

test_bpf: add 173 new testcases for eBPF

add an exhaustive set of eBPF tests bringing total to:
test_bpf: Summary: 233 PASSED, 0 FAILED, [0/226 JIT'ed]

Signed-off-by: Michael Ho

test_bpf: add 173 new testcases for eBPF

add an exhaustive set of eBPF tests bringing total to:
test_bpf: Summary: 233 PASSED, 0 FAILED, [0/226 JIT'ed]

Signed-off-by: Michael Holzheu <holzheu@linux.vnet.ibm.com>
Signed-off-by: Alexei Starovoitov <ast@plumgrid.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

show more ...

test: bpf: extend "load 64-bit immediate" testcase

Extend the testcase to catch a signedness bug in the arm64 JIT:

test_bpf: #58 load 64-bit immediate jited:1 ret -1 != 1 FAIL (1 ti

test: bpf: extend "load 64-bit immediate" testcase

Extend the testcase to catch a signedness bug in the arm64 JIT:

test_bpf: #58 load 64-bit immediate jited:1 ret -1 != 1 FAIL (1 times)

This is useful to ensure other JITs won't have a similar bug.

Link: https://lkml.org/lkml/2015/5/8/458
Cc: Alexei Starovoitov <ast@plumgrid.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Xi Wang <xi.wang@gmail.com>
Acked-by: Alexei Starovoitov <ast@plumgrid.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

show more ...

test_bpf: indicate whether bpf prog got jited in test suite

I think this is useful to verify whether a filter could be JITed or
not in case of bpf_prog_enable >= 1, which otherwise the t

test_bpf: indicate whether bpf prog got jited in test suite

I think this is useful to verify whether a filter could be JITed or
not in case of bpf_prog_enable >= 1, which otherwise the test suite
doesn't tell besides taking a good peek at the performance numbers.

Nicolas Schichan reported a bug in the ARM JIT compiler that rejected
and waved the filter to the interpreter although it shouldn't have.
Nevertheless, the test passes as expected, but such information is
not visible.

It's i.e. useful for the remaining classic JITs, but also for
implementing remaining opcodes that are not yet present in eBPF JITs
(e.g. ARM64 waves some of them to the interpreter). This minor patch
allows to grep through dmesg to find those accordingly, but also
provides a total summary, i.e.: [<X>/53 JIT'ed]

# echo 1 > /proc/sys/net/core/bpf_jit_enable
# insmod lib/test_bpf.ko
# dmesg | grep "jited:0"

dmesg example on the ARM issue with JIT rejection:

[...]
[ 67.925387] test_bpf: #2 ADD_SUB_MUL_K jited:1 24 PASS
[ 67.930889] test_bpf: #3 DIV_MOD_KX jited:0 794 PASS
[ 67.943940] test_bpf: #4 AND_OR_LSH_K jited:1 20 20 PASS
[...]

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Cc: Nicolas Schichan <nschichan@freebox.fr>
Cc: Alexei Starovoitov <ast@plumgrid.com>
Acked-by: Alexei Starovoitov <ast@plumgrid.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

show more ...

test: bpf: expand DIV_KX to DIV_MOD_KX

Expand DIV_KX to use BPF_MOD operation in the
DIV_KX bpf 'classic' test.

CC: Alexei Starovoitov <ast@plumgrid.com>
Signed-off-by: Deni

test: bpf: expand DIV_KX to DIV_MOD_KX

Expand DIV_KX to use BPF_MOD operation in the
DIV_KX bpf 'classic' test.

CC: Alexei Starovoitov <ast@plumgrid.com>
Signed-off-by: Denis Kirjanov <kda@linux-powerpc.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

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test: bpf: add a testcase reduced from nmap

nmap generates classic BPF programs to filter ARP packets with given target MAC
which triggered a bug in eBPF x64 JIT. The bug was fixed in

test: bpf: add a testcase reduced from nmap

nmap generates classic BPF programs to filter ARP packets with given target MAC
which triggered a bug in eBPF x64 JIT. The bug was fixed in
commit e0ee9c12157d ("x86: bpf_jit: fix two bugs in eBPF JIT compiler")
This patch is adding a testcase in eBPF instructions (those that
were generated by classic->eBPF converter) to be processed by JIT.
The test is primarily targeting JIT compiler.

Signed-off-by: Alexei Starovoitov <ast@plumgrid.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

show more ...

net: bpf: fix compiler warnings in test_bpf

old gcc 4.2 used by avr32 architecture produces warnings:

lib/test_bpf.c:1741: warning: integer constant is too large for 'long' type

net: bpf: fix compiler warnings in test_bpf

old gcc 4.2 used by avr32 architecture produces warnings:

lib/test_bpf.c:1741: warning: integer constant is too large for 'long' type
lib/test_bpf.c:1741: warning: integer constant is too large for 'long' type
lib/test_bpf.c: In function '__run_one':
lib/test_bpf.c:1897: warning: 'ret' may be used uninitialized in this function

silence these warnings.

Fixes: 02ab695bb37e ("net: filter: add "load 64-bit immediate" eBPF instruction")
Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Alexei Starovoitov <ast@plumgrid.com>
Acked-by: Daniel Borkmann <dborkman@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

show more ...

net: filter: add "load 64-bit immediate" eBPF instruction

add BPF_LD_IMM64 instruction to load 64-bit immediate value into a register.
All previous instructions were 8-byte. This is firs

net: filter: add "load 64-bit immediate" eBPF instruction

add BPF_LD_IMM64 instruction to load 64-bit immediate value into a register.
All previous instructions were 8-byte. This is first 16-byte instruction.
Two consecutive 'struct bpf_insn' blocks are interpreted as single instruction:
insn[0].code = BPF_LD | BPF_DW | BPF_IMM
insn[0].dst_reg = destination register
insn[0].imm = lower 32-bit
insn[1].code = 0
insn[1].imm = upper 32-bit
All unused fields must be zero.

Classic BPF has similar instruction: BPF_LD | BPF_W | BPF_IMM
which loads 32-bit immediate value into a register.

x64 JITs it as single 'movabsq %rax, imm64'
arm64 may JIT as sequence of four 'movk x0, #imm16, lsl #shift' insn

Note that old eBPF programs are binary compatible with new interpreter.

It helps eBPF programs load 64-bit constant into a register with one
instruction instead of using two registers and 4 instructions:
BPF_MOV32_IMM(R1, imm32)
BPF_ALU64_IMM(BPF_LSH, R1, 32)
BPF_MOV32_IMM(R2, imm32)
BPF_ALU64_REG(BPF_OR, R1, R2)

User space generated programs will use this instruction to load constants only.

To tell kernel that user space needs a pointer the _pseudo_ variant of
this instruction may be added later, which will use extra bits of encoding
to indicate what type of pointer user space is asking kernel to provide.
For example 'off' or 'src_reg' fields can be used for such purpose.
src_reg = 1 could mean that user space is asking kernel to validate and
load in-kernel map pointer.
src_reg = 2 could mean that user space needs readonly data section pointer
src_reg = 3 could mean that user space needs a pointer to per-cpu local data
All such future pseudo instructions will not be carrying the actual pointer
as part of the instruction, but rather will be treated as a request to kernel
to provide one. The kernel will verify the request_for_a_pointer, then
will drop _pseudo_ marking and will store actual internal pointer inside
the instruction, so the end result is the interpreter and JITs never
see pseudo BPF_LD_IMM64 insns and only operate on generic BPF_LD_IMM64 that
loads 64-bit immediate into a register. User space never operates on direct
pointers and verifier can easily recognize request_for_pointer vs other
instructions.

Signed-off-by: Alexei Starovoitov <ast@plumgrid.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

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