Peter Zijlstra dceba0817c bpf,x86: Simplify computing label offsets ... Take an idea from the 32bit JIT, which uses the multi-pass nature of the JIT to compute the instruction offsets on a prior pass in order to compute the relative jump offsets on a later pass. Application to the x86_64 JIT is slightly more involved because the offsets depend on program variables (such as callee_regs_used and stack_depth) and hence the computed offsets need to be kept in the context of the JIT. This removes, IMO quite fragile, code that hard-codes the offsets and tries to compute the length of variable parts of it. Convert both emit_bpf_tail_call_*() functions which have an out: label at the end. Additionally emit_bpt_tail_call_direct() also has a poke table entry, for which it computes the offset from the end (and thus already relies on the previous pass to have computed addrs[i]), also convert this to be a forward based offset. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Borislav Petkov <bp@suse.de> Acked-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Josh Poimboeuf <jpoimboe@redhat.com> Tested-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/r/20211026120310.552304864@infradead.org		2021-10-28 23:25:29 +02:00
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bpf_jit_comp32.c	bpf: Introduce BPF nospec instruction for mitigating Spectre v4	2021-07-29 00:20:56 +02:00
bpf_jit_comp.c	bpf,x86: Simplify computing label offsets	2021-10-28 23:25:29 +02:00
Makefile	treewide: Add SPDX license identifier - Makefile/Kconfig	2019-05-21 10:50:46 +02:00