Date: Fri, 22 Nov 2024 09:07:22 -0500 From: Mark Johnston <markj@freebsd.org> To: Alan Somers <asomers@freebsd.org> Cc: FreeBSD Hackers <freebsd-hackers@freebsd.org> Subject: Re: KMSAN and dtrace Message-ID: <Z0CQGsUOHbpifvOp@nuc> In-Reply-To: <CAOtMX2i46vwjUD5=fJHe_PZM=ucw8HD9jZQfHvjcYqR1XF7p_A@mail.gmail.com> References: <CAOtMX2i46vwjUD5=fJHe_PZM=ucw8HD9jZQfHvjcYqR1XF7p_A@mail.gmail.com>
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On Thu, Nov 21, 2024 at 04:06:53PM -0700, Alan Somers wrote: > Would it be possible to make dtrace with with KMSAN? It would > certainly make my life easier. As it is, every time I try to kldload > traceall, whether from the command line or in the loader, my VM > infinite loops printing alerts like this: > > MSan: Uninitialized stack memory from isize64+0x2e > #0 0xffffffff833d8f10 at __msan_warning+0x140 > #1 0xffffffff86ec9c03 at dtrace_disp_opnd+0xd3 > #2 0xffffffff86ebe552 at dtrace_disx86+0xc602 > #3 0xffffffff86eca98e at dtrace_instr_size+0xee > #4 0xffffffff86d5ec27 at fbt_provide_module_function+0x957 > #5 0xffffffff83303eff at link_elf_each_function_nameval+0x56f > #6 0xffffffff86d56cb3 at fbt_provide_module+0x423 > #7 0xffffffff86d56871 at fbt_linker_file_cb+0x41 > #8 0xffffffff830d9f5c at linker_file_foreach+0xdc > #9 0xffffffff830d63dd at linker_load_module+0x413d > #10 0xffffffff830e6116 at linker_load_dependencies+0x1136 > #11 0xffffffff853b70b8 at link_elf_load_file+0x65c8 > #12 0xffffffff830d542e at linker_load_module+0x318e > #13 0xffffffff830e0611 at kern_kldload+0x5d1 > #14 0xffffffff830e0d74 at sys_kldload+0x1a4 > #15 0xffffffff84fe56f6 at amd64_syscall+0x706 > #16 0xffffffff84f0ef4b at fast_syscall_common+0xf8 > Here you go: https://cgit.freebsd.org/src/commit/?id=418d8f0dc269b314bba51de63869b20da1d9a76e https://cgit.freebsd.org/src/commit/?id=cc3da1955c16df5eb0019e0fef810696b035b7cf This one might also be important if your test system is low on RAM, since the KMSAN shadow map gobbles up quite a lot of memory: https://cgit.freebsd.org/src/commit/?id=5d12db2dafece9f6a0453c4a45c4abed6b1e15ec I haven't yet tried running through the full test suite, but this was enough to load dtracell (quite slow under KMSAN) and run some simple scripts.
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