linux-dev/arch/s390/net, branch master

s390/bpf: Fix typo in comment

2022-05-23T18:25:53Z

Spelling mistake (triple letters) in comment. Detected with the help of Coccinelle. Signed-off-by: Julia Lawall Signed-off-by: Andrii Nakryiko Acked-by: Ilya Leoshkevich Link: https://lore.kernel.org/bpf/20220521111145.81697-84-Julia.Lawall@inria.fr

s390: raise minimum supported machine generation to z10

2022-03-10T14:58:17Z

Machine generations up to z9 (released in May 2006) have been officially out of service for several years now (z9 end of service - January 31, 2019). No distributions build kernels supporting those old machine generations anymore, except Debian, which seems to pick the oldest supported generation. The team supporting Debian on s390 has been notified about the change. Raising minimum supported machine generation to z10 helps to reduce maintenance cost and effectively remove code, which is not getting enough testing coverage due to lack of older hardware and distributions support. Besides that this unblocks some optimization opportunities and allows to use wider instruction set in asm files for future features implementation. Due to this change spectre mitigation and usercopy implementations could be drastically simplified and many newer instructions could be converted from ".insn" encoding to instruction names. Acked-by: Ilya Leoshkevich Reviewed-by: Heiko Carstens Signed-off-by: Vasily Gorbik

s390/bpf: encode register within extable entry

2022-03-07T23:33:00Z

Instead of decoding the instruction that faulted to get the register which needs to be zeroed, simply encode its number into the extable entries during code generation. This allows to get rid of a bit of code, and is also what other architectures are doing. Acked-by: Alexander Gordeev Reviewed-by: Ilya Leoshkevich Tested-by: Ilya Leoshkevich Signed-off-by: Heiko Carstens Signed-off-by: Vasily Gorbik

s390/extable: convert to relative table with data

2022-03-07T23:33:00Z

Follow arm64, riscv, and x86 and change extable layout to common "relative table with data". This allows to get rid of s390 specific code in sorttable.c. The main difference to before is that extable entries do not contain a relative function pointer anymore. Instead data and type fields are added. The type field is used to indicate which exception handler needs to be called, while the data field is currently unused. Acked-by: Alexander Gordeev Signed-off-by: Heiko Carstens Signed-off-by: Vasily Gorbik

s390/extable: move EX_TABLE define to asm-extable.h

2022-03-07T23:33:00Z

Follow arm64 and riscv and move the EX_TABLE define to asm-extable.h which is a lot less generic than the current linkage.h. Also make sure that all files which contain EX_TABLE usages actually include the new header file. This should make sure that the files always compile and there won't be any random compile breakage due to other header file dependencies. Reviewed-by: Alexander Gordeev Signed-off-by: Heiko Carstens Signed-off-by: Vasily Gorbik

s390: always use the packed stack layout

2022-03-01T20:05:09Z

-mpacked-stack option has been supported by both minimum gcc and clang versions for a while. With commit e2bc3e91d91e ("scripts/min-tool-version.sh: Raise minimum clang version to 13.0.0 for s390") minimum clang version now also supports a combination of flags -mpacked-stack -mbackchain -pg -mfentry and fulfills all requirements to always enable the packed stack layout. Reviewed-by: Heiko Carstens Signed-off-by: Vasily Gorbik

bpf: Change value of MAX_TAIL_CALL_CNT from 32 to 33

2021-11-16T13:03:15Z

In the current code, the actual max tail call count is 33 which is greater than MAX_TAIL_CALL_CNT (defined as 32). The actual limit is not consistent with the meaning of MAX_TAIL_CALL_CNT and thus confusing at first glance. We can see the historical evolution from commit 04fd61ab36ec ("bpf: allow bpf programs to tail-call other bpf programs") and commit f9dabe016b63 ("bpf: Undo off-by-one in interpreter tail call count limit"). In order to avoid changing existing behavior, the actual limit is 33 now, this is reasonable. After commit 874be05f525e ("bpf, tests: Add tail call test suite"), we can see there exists failed testcase. On all archs when CONFIG_BPF_JIT_ALWAYS_ON is not set: # echo 0 > /proc/sys/net/core/bpf_jit_enable # modprobe test_bpf # dmesg | grep -w FAIL Tail call error path, max count reached jited:0 ret 34 != 33 FAIL On some archs: # echo 1 > /proc/sys/net/core/bpf_jit_enable # modprobe test_bpf # dmesg | grep -w FAIL Tail call error path, max count reached jited:1 ret 34 != 33 FAIL Although the above failed testcase has been fixed in commit 18935a72eb25 ("bpf/tests: Fix error in tail call limit tests"), it would still be good to change the value of MAX_TAIL_CALL_CNT from 32 to 33 to make the code more readable. The 32-bit x86 JIT was using a limit of 32, just fix the wrong comments and limit to 33 tail calls as the constant MAX_TAIL_CALL_CNT updated. For the mips64 JIT, use "ori" instead of "addiu" as suggested by Johan Almbladh. For the riscv JIT, use RV_REG_TCC directly to save one register move as suggested by Björn Töpel. For the other implementations, no function changes, it does not change the current limit 33, the new value of MAX_TAIL_CALL_CNT can reflect the actual max tail call count, the related tail call testcases in test_bpf module and selftests can work well for the interpreter and the JIT. Here are the test results on x86_64: # uname -m x86_64 # echo 0 > /proc/sys/net/core/bpf_jit_enable # modprobe test_bpf test_suite=test_tail_calls # dmesg | tail -1 test_bpf: test_tail_calls: Summary: 8 PASSED, 0 FAILED, [0/8 JIT'ed] # rmmod test_bpf # echo 1 > /proc/sys/net/core/bpf_jit_enable # modprobe test_bpf test_suite=test_tail_calls # dmesg | tail -1 test_bpf: test_tail_calls: Summary: 8 PASSED, 0 FAILED, [8/8 JIT'ed] # rmmod test_bpf # ./test_progs -t tailcalls #142 tailcalls:OK Summary: 1/11 PASSED, 0 SKIPPED, 0 FAILED Signed-off-by: Tiezhu Yang Signed-off-by: Daniel Borkmann Tested-by: Johan Almbladh Tested-by: Ilya Leoshkevich Acked-by: Björn Töpel Acked-by: Johan Almbladh Acked-by: Ilya Leoshkevich Link: https://lore.kernel.org/bpf/1636075800-3264-1-git-send-email-yangtiezhu@loongson.cn

s390: introduce nospec_uses_trampoline()

2021-10-26T13:21:29Z

and replace all of the "__is_defined(CC_USING_EXPOLINE) && !nospec_disable" occurrences. Signed-off-by: Sven Schnelle Reviewed-by: Heiko Carstens Signed-off-by: Vasily Gorbik

bpf, s390: Fix potential memory leak about jit_data

2021-10-04T07:49:10Z

Make sure to free jit_data through kfree() in the error path. Fixes: 1c8f9b91c456 ("bpf: s390: add JIT support for multi-function programs") Signed-off-by: Tiezhu Yang Acked-by: Ilya Leoshkevich Reviewed-by: Christian Borntraeger Signed-off-by: Christian Borntraeger Signed-off-by: Vasily Gorbik

s390/bpf: Fix optimizing out zero-extensions

2021-09-16T08:39:55Z

Currently the JIT completely removes things like `reg32 += 0`, however, the BPF_ALU semantics requires the target register to be zero-extended in such cases. Fix by optimizing out only the arithmetic operation, but not the subsequent zero-extension. Reported-by: Johan Almbladh Fixes: 054623105728 ("s390/bpf: Add s390x eBPF JIT compiler backend") Reviewed-by: Heiko Carstens Signed-off-by: Ilya Leoshkevich Signed-off-by: Vasily Gorbik