From 34cc0b338a61de3eee3a2bfcaf4f9d6e9fae091a Mon Sep 17 00:00:00 2001 From: Jesper Dangaard Brouer Date: Thu, 14 May 2020 12:49:33 +0200 Subject: xdp: Xdp_frame add member frame_sz and handle in convert_to_xdp_frame MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Use hole in struct xdp_frame, when adding member frame_sz, which keeps same sizeof struct (32 bytes) Drivers ixgbe and sfc had bug cases where the necessary/expected tailroom was not reserved. This can lead to some hard to catch memory corruption issues. Having the drivers frame_sz this can be detected when packet length/end via xdp->data_end exceed the xdp_data_hard_end pointer, which accounts for the reserved the tailroom. When detecting this driver issue, simply fail the conversion with NULL, which results in feedback to driver (failing xdp_do_redirect()) causing driver to drop packet. Given the lack of consistent XDP stats, this can be hard to troubleshoot. And given this is a driver bug, we want to generate some more noise in form of a WARN stack dump (to ID the driver code that inlined convert_to_xdp_frame). Inlining the WARN macro is problematic, because it adds an asm instruction (on Intel CPUs ud2) what influence instruction cache prefetching. Thus, introduce xdp_warn and macro XDP_WARN, to avoid this and at the same time make identifying the function and line of this inlined function easier. Signed-off-by: Jesper Dangaard Brouer Signed-off-by: Alexei Starovoitov Acked-by: Toke Høiland-Jørgensen Link: https://lore.kernel.org/bpf/158945337313.97035.10015729316710496600.stgit@firesoul --- net/core/xdp.c | 8 ++++++++ 1 file changed, 8 insertions(+) (limited to 'net') diff --git a/net/core/xdp.c b/net/core/xdp.c index 4c7ea85486af..490b8f5fa8ee 100644 --- a/net/core/xdp.c +++ b/net/core/xdp.c @@ -11,6 +11,7 @@ #include #include #include +#include #include #include @@ -496,3 +497,10 @@ struct xdp_frame *xdp_convert_zc_to_xdp_frame(struct xdp_buff *xdp) return xdpf; } EXPORT_SYMBOL_GPL(xdp_convert_zc_to_xdp_frame); + +/* Used by XDP_WARN macro, to avoid inlining WARN() in fast-path */ +void xdp_warn(const char *msg, const char *func, const int line) +{ + WARN(1, "XDP_WARN: %s(line:%d): %s\n", func, line, msg); +}; +EXPORT_SYMBOL_GPL(xdp_warn); -- cgit v1.2.3