mainlining shenanigans
854dc87d1a
This patch adds support for backward jump on NFP. - restrictions on backward jump in various functions have been removed. - nfp_fixup_branches now supports backward jump. There is one thing to note, currently an input eBPF JMP insn may generate several NFP insns, for example, NFP imm move insn A \ NFP compare insn B --> 3 NFP insn jited from eBPF JMP insn M NFP branch insn C / --- NFP insn X --> 1 NFP insn jited from eBPF insn N --- ... therefore, we are doing sanity check to make sure the last jited insn from an eBPF JMP is a NFP branch instruction. Once backward jump is allowed, it is possible an eBPF JMP insn is at the end of the program. This is however causing trouble for the sanity check. Because the sanity check requires the end index of the NFP insns jited from one eBPF insn while only the start index is recorded before this patch that we can only get the end index by: start_index_of_the_next_eBPF_insn - 1 or for the above example: start_index_of_eBPF_insn_N (which is the index of NFP insn X) - 1 nfp_fixup_branches was using nfp_for_each_insn_walk2 to expose *next* insn to each iteration during the traversal so the last index could be calculated from which. Now, it needs some extra code to handle the last insn. Meanwhile, the use of walk2 is actually unnecessary, we could simply use generic single instruction walk to do this, the next insn could be easily calculated using list_next_entry. So, this patch migrates the jump fixup traversal method to *list_for_each_entry*, this simplifies the code logic a little bit. The other thing to note is a new state variable "last_bpf_off" is introduced to track the index of the last jited NFP insn. This is necessary because NFP is generating special purposes epilogue sequences, so the index of the last jited NFP insn is *not* always nfp_prog->prog_len - 1. Suggested-by: Jakub Kicinski <jakub.kicinski@netronome.com> Signed-off-by: Jiong Wang <jiong.wang@netronome.com> Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> |
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Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. Please read the Documentation/process/changes.rst file, as it contains the requirements for building and running the kernel, and information about the problems which may result by upgrading your kernel.