Eric Dumazet 7de0869093 powerpc/bpf: Fix tail call implementation ... We have seen many crashes on powerpc hosts while loading bpf programs. The problem here is that bpf_int_jit_compile() does a first pass to compute the program length. Then it allocates memory to store the generated program and calls bpf_jit_build_body() a second time (and a third time later) What I have observed is that the second bpf_jit_build_body() could end up using few more words than expected. If bpf_jit_binary_alloc() put the space for the program at the end of the allocated page, we then write on a non mapped memory. It appears that bpf_jit_emit_tail_call() calls bpf_jit_emit_common_epilogue() while ctx->seen might not be stable. Only after the second pass we can be sure ctx->seen wont be changed. Trying to avoid a second pass seems quite complex and probably not worth it. Fixes: ce0761419f ("powerpc/bpf: Implement support for tail calls") Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Cc: Naveen N. Rao <naveen.n.rao@linux.ibm.com> Cc: Sandipan Das <sandipan@linux.ibm.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Martin KaFai Lau <kafai@fb.com> Cc: Song Liu <songliubraving@fb.com> Cc: Yonghong Song <yhs@fb.com> Link: https://lore.kernel.org/bpf/20191101033444.143741-1-edumazet@google.com		2019-11-02 00:32:26 +01:00
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bpf_jit32.h
bpf_jit64.h
bpf_jit_asm.S
bpf_jit_comp64.c	powerpc/bpf: Fix tail call implementation	2019-11-02 00:32:26 +01:00
bpf_jit_comp.c
bpf_jit.h
Makefile