Date: Thu, 4 May 2023 18:11:06 +0800 From: Zhenlei Huang <zlei@FreeBSD.org> To: Konstantin Belousov <kostikbel@gmail.com> Cc: Hans Petter Selasky <hselasky@freebsd.org>, FreeBSD CURRENT <freebsd-current@freebsd.org>, Gleb Smirnoff <glebius@freebsd.org> Subject: Re: Link modules to DYN type Message-ID: <B2F70E53-BC01-4E13-925F-589CF1A9B5B7@FreeBSD.org> In-Reply-To: <86DC0C8E-56E8-49B9-8441-D64C690FA5F0@FreeBSD.org> References: <97390FE1-1DF5-43A1-A3F4-2B945D681437@FreeBSD.org> <2bb66cac-c7f1-e45b-693a-8afbda05cfa6@freebsd.org> <ZEkHKJ_BRhV22gf_@kib.kiev.ua> <86DC0C8E-56E8-49B9-8441-D64C690FA5F0@FreeBSD.org>
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[-- Attachment #1 --] > On Apr 28, 2023, at 12:32 AM, Zhenlei Huang <zlei@FreeBSD.org> wrote: > > > >> On Apr 26, 2023, at 7:12 PM, Konstantin Belousov <kostikbel@gmail.com <mailto:kostikbel@gmail.com>> wrote: >> >> On Wed, Apr 26, 2023 at 12:55:02PM +0200, Hans Petter Selasky wrote: >>> On 4/26/23 12:36, Zhenlei Huang wrote: >>>> Hi, >>>> >>>> I'm recently working on https://reviews.freebsd.org/D39638 <https://reviews.freebsd.org/D39638>; (sysctl(9): Enable vnet sysctl variables be loader tunable), >>>> the changes to `sys/kern/link_elf_obj.c` are runtime tested, but not those to `sys/kern/link_elf.c` . >>>> >>>> After some hacking I realized that `link_elf.c` is for EXEC (Executable file) or DYN (Shared object file), and `link_elf_obj.c` is >>>> for REL (Relocatable file). >>>> >>>> ``` >>>> /* link_elf.c */ >>>> static int >>>> link_elf_load_file(linker_class_t cls, const char* filename, >>>> linker_file_t* result) >>>> { >>>> ... >>>> if (hdr->e_type != ET_EXEC && hdr->e_type != ET_DYN) { >>>> error = ENOSYS; >>>> goto out; >>>> } >>>> ... >>>> } >>>> >>>> >>>> /* link_elf_obj.c */ >>>> static int >>>> link_elf_load_file(linker_class_t cls, const char *filename, >>>> linker_file_t *result) >>>> { >>>> ... >>>> if (hdr->e_type != ET_REL) { >>>> error = ENOSYS; >>>> goto out; >>>> } >>>> ... >>>> } >>>> ``` >>>> >>>> Run the following snip: >>>> ``` >>>> # find /boot/kernel -type f -name "*.ko" -exec readelf -h {} \; | grep Type >>>> ``` >>>> shows that all the kernel modules' types are `REL (Relocatable file)`. >>>> >>>> I guess if some module such as if_bridge is linked to DYN type, then I can do runtime for the changes to `sys/kern/link_elf.c`. >>>> >>>> I'm not familiar with elf and linkers, is that ( compile module and link it to DYN type ) possible ? >> >> Module file type (shared object vs. object file) depends on architecture. >> For amd64 modules are objects, while kernel is shared library. >> For arm64 (and all other arches, I believe) modules and kernels are shared >> libraries. >> >> I think you can link amd64 module as shared object, but this require enough >> hacking of the build infrastructure. At least I am not aware of a simple >> knob to switch the produced type. > > I did some hack on `sys/conf/kmod.mk` and finally produced DYN kernel modules. > The good news is I do some basic sysctl tests, but the bad news is the module does not function correctly. > > For exampe the if_disc.c > > ``` > static void > vnet_disc_init(const void *unused __unused) > { > /* Reference V_disc_cloner will immediately trigger page fault panic */ > V_disc_cloner = if_clone_simple(discname, disc_clone_create, > disc_clone_destroy, 0); > } > VNET_SYSINIT(vnet_disc_init, SI_SUB_PSEUDO, SI_ORDER_ANY, > vnet_disc_init, NULL); > ``` > > I suspect the relocation is not done correctly for DYN elf kmod on amd64. > > My local patch to kmod.mk: > > ``` > diff --git a/sys/conf/kmod.mk b/sys/conf/kmod.mk > index 134b150af1d9..1fc5386204a5 100644 > --- a/sys/conf/kmod.mk > +++ b/sys/conf/kmod.mk > @@ -84,6 +84,7 @@ __KLD_SHARED=yes > .else > __KLD_SHARED=no > .endif > +__KLD_SHARED=yes > > .if !empty(CFLAGS:M-O[23s]) && empty(CFLAGS:M-fno-strict-aliasing) > CFLAGS+= -fno-strict-aliasing > @@ -167,6 +168,7 @@ CFLAGS+= -fno-omit-frame-pointer -mno-omit-leaf-frame-pointer > ${MACHINE_CPUARCH} == "powerpc" > CFLAGS+= -fPIC > .endif > +CFLAGS+= -fPIC > > # Temporary workaround for PR 196407, which contains the fascinating details. > # Don't allow clang to use fpu instructions or registers in kernel modules. > ``` > > > As for https://reviews.freebsd.org/D39638 <https://reviews.freebsd.org/D39638>, for other platform such as arm, I think the `link_elf_propagate_vnets()` should work if `parse_vnet()` works. > > I'll appreciate if someone can test it on platforms those have DYN type kernel modules. Good news on this! I've managed to test the change for `link_elf.c` on QEMU RISCV . It works as expected and solid ! > >> >> >>>> >>> >>> Hi, >>> >>> I don't have an answer for you either, but I have seen in the past, loading >>> kernel modules behaves a bit like libraries, in the following regard: >>> >>> If two kernel modules define the same global symbol, then no warning is >>> given and the first loaded symbol definition (I think) is used to resolve >>> that symbol for all kernel modules, regardless of the prototype. Probably we >>> should not allow this. That's why building LINT is a good thing, to avoid >>> this issue. >> No, in-kernel linker does not behave this way. >> Modules need to contain explicit reference to all modules they depend upon, >> using the MODULE_DEPEND() macro. Only symbols from the dependencies are >> resolved. >> >> All modules get an implicit reference to kernel. >> >>> >>> Even if we don't have C++ support in the FreeBSD kernel, defining symbol >>> names the way C++ does for C could be nice for the kernel too, also with >>> regards to debugging systems. >>> >>> Many times when I don't know what is going on, I do like this: >>> >>> #include <sys/kdb.h> >>> >>> .... >>> >>> if (not too fast or my sysctl debug) { >>> printf("My tracer\n"); >>> kdb_backtrace(); >>> } >>> >>> Dtrace can also do this, but not during boot. Just track who is calling >>> those functions, and you'll probably find the answer to your question! >>> >>> --HPS >>> >>>> >>>> Best regards, >>>> Zhenlei [-- Attachment #2 --] <html><head><meta http-equiv="Content-Type" content="text/html; charset=us-ascii"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;" class=""><br class=""><div><br class=""><blockquote type="cite" class=""><div class="">On Apr 28, 2023, at 12:32 AM, Zhenlei Huang <<a href="mailto:zlei@FreeBSD.org" class="">zlei@FreeBSD.org</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><meta charset="UTF-8" class=""><br class="Apple-interchange-newline"><br class="" style="caret-color: rgb(0, 0, 0); font-family: Helvetica; font-size: 13px; font-style: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none;"><blockquote type="cite" class="" style="font-family: Helvetica; font-size: 13px; font-style: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; text-decoration: none;"><div class="">On Apr 26, 2023, at 7:12 PM, Konstantin Belousov <<a href="mailto:kostikbel@gmail.com" class="">kostikbel@gmail.com</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><span class="" style="caret-color: rgb(0, 0, 0); font-family: Menlo-Regular; font-size: 13px; font-style: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none; float: none; display: inline !important;">On Wed, Apr 26, 2023 at 12:55:02PM +0200, Hans Petter Selasky wrote:</span><br class="" style="caret-color: rgb(0, 0, 0); font-family: Menlo-Regular; font-size: 13px; font-style: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none;"><blockquote type="cite" class="" style="font-family: Menlo-Regular; font-size: 13px; font-style: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none;">On 4/26/23 12:36, Zhenlei Huang wrote:<br class=""><blockquote type="cite" class="">Hi,<br class=""><br class="">I'm recently working on<span class="Apple-converted-space"> </span><a href="https://reviews.freebsd.org/D39638" class="">https://reviews.freebsd.org/D39638</a><span class="Apple-converted-space"> </span>(sysctl(9): Enable vnet sysctl variables be loader tunable),<br class="">the changes to `sys/kern/link_elf_obj.c` are runtime tested, but not those to `sys/kern/link_elf.c` .<br class=""><br class="">After some hacking I realized that `link_elf.c` is for EXEC (Executable file) or DYN (Shared object file), and `link_elf_obj.c` is<br class="">for REL (Relocatable file).<br class=""><br class="">```<br class="">/* link_elf.c */<br class="">static int<br class="">link_elf_load_file(linker_class_t cls, const char* filename,<br class=""> linker_file_t* result)<br class="">{<br class="">...<br class=""><span class="Apple-tab-span" style="white-space: pre;"> </span>if (hdr->e_type != ET_EXEC && hdr->e_type != ET_DYN) {<br class=""><span class="Apple-tab-span" style="white-space: pre;"> </span><span class="Apple-tab-span" style="white-space: pre;"> </span>error = ENOSYS;<br class=""><span class="Apple-tab-span" style="white-space: pre;"> </span><span class="Apple-tab-span" style="white-space: pre;"> </span>goto out;<br class=""><span class="Apple-tab-span" style="white-space: pre;"> </span>}<br class="">...<br class="">}<br class=""><br class=""><br class="">/* link_elf_obj.c */<br class="">static int<br class="">link_elf_load_file(linker_class_t cls, const char *filename,<br class=""> linker_file_t *result)<br class="">{<br class="">...<br class=""><span class="Apple-tab-span" style="white-space: pre;"> </span>if (hdr->e_type != ET_REL) {<br class=""><span class="Apple-tab-span" style="white-space: pre;"> </span><span class="Apple-tab-span" style="white-space: pre;"> </span>error = ENOSYS;<br class=""><span class="Apple-tab-span" style="white-space: pre;"> </span><span class="Apple-tab-span" style="white-space: pre;"> </span>goto out;<br class=""><span class="Apple-tab-span" style="white-space: pre;"> </span>}<br class="">...<br class="">}<br class="">```<br class=""><br class="">Run the following snip:<br class="">```<br class=""># find /boot/kernel -type f -name "*.ko" -exec readelf -h {} \; | grep Type<br class="">```<br class="">shows that all the kernel modules' types are `REL (Relocatable file)`.<br class=""><br class="">I guess if some module such as if_bridge is linked to DYN type, then I can do runtime for the changes to `sys/kern/link_elf.c`.<br class=""><br class="">I'm not familiar with elf and linkers, is that ( compile module and link it to DYN type ) possible ?<br class=""></blockquote></blockquote><br class="" style="caret-color: rgb(0, 0, 0); font-family: Menlo-Regular; font-size: 13px; font-style: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none;"><span class="" style="caret-color: rgb(0, 0, 0); font-family: Menlo-Regular; font-size: 13px; font-style: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none; float: none; display: inline !important;">Module file type (shared object vs. object file) depends on architecture.</span><br class="" style="caret-color: rgb(0, 0, 0); font-family: Menlo-Regular; font-size: 13px; font-style: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none;"><span class="" style="caret-color: rgb(0, 0, 0); font-family: Menlo-Regular; font-size: 13px; font-style: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none; float: none; display: inline !important;">For amd64 modules are objects, while kernel is shared library.</span><br class="" style="caret-color: rgb(0, 0, 0); font-family: Menlo-Regular; font-size: 13px; font-style: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none;"><span class="" style="caret-color: rgb(0, 0, 0); font-family: Menlo-Regular; font-size: 13px; font-style: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none; float: none; display: inline !important;">For arm64 (and all other arches, I believe) modules and kernels are shared</span><br class="" style="caret-color: rgb(0, 0, 0); font-family: Menlo-Regular; font-size: 13px; font-style: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none;"><span class="" style="caret-color: rgb(0, 0, 0); font-family: Menlo-Regular; font-size: 13px; font-style: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none; float: none; display: inline !important;">libraries.</span></div></blockquote><blockquote type="cite" class="" style="font-family: Helvetica; font-size: 13px; font-style: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; text-decoration: none;"><div class=""><br class="" style="caret-color: rgb(0, 0, 0); font-family: Menlo-Regular; font-size: 13px; font-style: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none;"><span class="" style="caret-color: rgb(0, 0, 0); font-family: Menlo-Regular; font-size: 13px; font-style: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none; float: none; display: inline !important;">I think you can link amd64 module as shared object, but this require enough</span><br class="" style="caret-color: rgb(0, 0, 0); font-family: Menlo-Regular; font-size: 13px; font-style: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none;"><span class="" style="caret-color: rgb(0, 0, 0); font-family: Menlo-Regular; font-size: 13px; font-style: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none; float: none; display: inline !important;">hacking of the build infrastructure. At least I am not aware of a simple</span><br class="" style="caret-color: rgb(0, 0, 0); font-family: Menlo-Regular; font-size: 13px; font-style: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none;"><span class="" style="caret-color: rgb(0, 0, 0); font-family: Menlo-Regular; font-size: 13px; font-style: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none; float: none; display: inline !important;">knob to switch the produced type.</span><br class="" style="caret-color: rgb(0, 0, 0); font-family: Menlo-Regular; font-size: 13px; font-style: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none;"></div></blockquote><div style="caret-color: rgb(0, 0, 0); font-family: Helvetica; font-size: 13px; font-style: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none;" class=""><br class=""></div><div style="caret-color: rgb(0, 0, 0); font-family: Helvetica; font-size: 13px; font-style: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none;" class=""><div style="caret-color: rgb(0, 0, 0);" class="">I did some hack on `sys/conf/kmod.mk` and finally produced DYN kernel modules.</div><div style="caret-color: rgb(0, 0, 0);" class="">The good news is I do some basic sysctl tests, but the bad news is the module does not function correctly.</div><div style="caret-color: rgb(0, 0, 0);" class=""><br class=""></div><div style="caret-color: rgb(0, 0, 0);" class="">For exampe the if_disc.c</div><div style="caret-color: rgb(0, 0, 0);" class=""><br class=""></div><div style="caret-color: rgb(0, 0, 0);" class="">```</div><div class=""><div class=""><font class=""><span class="" style="caret-color: rgb(0, 0, 0);">static void</span></font></div><div class=""><font class=""><span class="" style="caret-color: rgb(0, 0, 0);">vnet_disc_init(const void *unused __unused)</span></font></div><div class=""><font class=""><span class="" style="caret-color: rgb(0, 0, 0);">{</span></font></div><div class=""><span class="Apple-tab-span" style="caret-color: rgb(0, 0, 0); white-space: pre;"> </span>/* Reference V_disc_cloner will immediately trigger page fault panic */</div><div class=""><font class=""><span class="" style="caret-color: rgb(0, 0, 0);"><span class="Apple-tab-span" style="white-space: pre;"> </span>V_disc_cloner = if_clone_simple(discname, disc_clone_create,</span></font></div><div class=""><font class=""><span class="" style="caret-color: rgb(0, 0, 0);"><span class="Apple-tab-span" style="white-space: pre;"> </span><span class="Apple-converted-space"> </span> disc_clone_destroy, 0);</span></font></div><div class=""><font class=""><span class="" style="caret-color: rgb(0, 0, 0);">}</span></font></div><div class=""><font class=""><span class="" style="caret-color: rgb(0, 0, 0);">VNET_SYSINIT(vnet_disc_init, SI_SUB_PSEUDO, SI_ORDER_ANY,</span></font></div><div class=""><font class=""><span class="" style="caret-color: rgb(0, 0, 0);"> vnet_disc_init, NULL);</span></font></div></div><div style="caret-color: rgb(0, 0, 0);" class="">```</div><div style="caret-color: rgb(0, 0, 0);" class=""><br class=""></div></div><div style="caret-color: rgb(0, 0, 0); font-family: Helvetica; font-size: 13px; font-style: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none;" class="">I suspect the relocation is not done correctly for <span class="" style="caret-color: rgb(0, 0, 0);">DYN elf kmod on amd64.</span></div><div style="caret-color: rgb(0, 0, 0); font-family: Helvetica; font-size: 13px; font-style: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none;" class=""><span class="" style="caret-color: rgb(0, 0, 0);"><br class=""></span></div><div style="caret-color: rgb(0, 0, 0); font-family: Helvetica; font-size: 13px; font-style: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none;" class=""><span class="" style="caret-color: rgb(0, 0, 0);">My local patch to kmod.mk:</span></div><div style="caret-color: rgb(0, 0, 0); font-family: Helvetica; font-size: 13px; font-style: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none;" class=""><span class="" style="caret-color: rgb(0, 0, 0);"><br class=""></span></div><div style="caret-color: rgb(0, 0, 0); font-family: Helvetica; font-size: 13px; font-style: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none;" class=""><span class="" style="caret-color: rgb(0, 0, 0);">```</span></div><div style="caret-color: rgb(0, 0, 0); font-family: Helvetica; font-size: 13px; font-style: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none;" class=""><div class=""><font class=""><span class="" style="caret-color: rgb(0, 0, 0);">diff --git a/sys/conf/kmod.mk b/sys/conf/kmod.mk</span></font></div><div class=""><font class=""><span class="" style="caret-color: rgb(0, 0, 0);">index 134b150af1d9..1fc5386204a5 100644</span></font></div><div class=""><font class=""><span class="" style="caret-color: rgb(0, 0, 0);">--- a/sys/conf/kmod.mk</span></font></div><div class=""><font class=""><span class="" style="caret-color: rgb(0, 0, 0);">+++ b/sys/conf/kmod.mk</span></font></div><div class=""><font class=""><span class="" style="caret-color: rgb(0, 0, 0);">@@ -84,6 +84,7 @@ __KLD_SHARED=yes</span></font></div><div class=""><font class=""><span class="" style="caret-color: rgb(0, 0, 0);"> .else</span></font></div><div class=""><font class=""><span class="" style="caret-color: rgb(0, 0, 0);"> __KLD_SHARED=no</span></font></div><div class=""><font class=""><span class="" style="caret-color: rgb(0, 0, 0);"> .endif</span></font></div><div class=""><font class=""><span class="" style="caret-color: rgb(0, 0, 0);">+__KLD_SHARED=yes</span></font></div><div class=""><font class=""><span class="" style="caret-color: rgb(0, 0, 0);"> </span></font></div><div class=""><font class=""><span class="" style="caret-color: rgb(0, 0, 0);"> .if !empty(CFLAGS:M-O[23s]) && empty(CFLAGS:M-fno-strict-aliasing)</span></font></div><div class=""><font class=""><span class="" style="caret-color: rgb(0, 0, 0);"> CFLAGS+= -fno-strict-aliasing</span></font></div><div class=""><font class=""><span class="" style="caret-color: rgb(0, 0, 0);">@@ -167,6 +168,7 @@ CFLAGS+= -fno-omit-frame-pointer -mno-omit-leaf-frame-pointer</span></font></div><div class=""><font class=""><span class="" style="caret-color: rgb(0, 0, 0);"> ${MACHINE_CPUARCH} == "powerpc"</span></font></div><div class=""><font class=""><span class="" style="caret-color: rgb(0, 0, 0);"> CFLAGS+= -fPIC</span></font></div><div class=""><font class=""><span class="" style="caret-color: rgb(0, 0, 0);"> .endif</span></font></div><div class=""><font class=""><span class="" style="caret-color: rgb(0, 0, 0);">+CFLAGS+= -fPIC</span></font></div><div class=""><font class=""><span class="" style="caret-color: rgb(0, 0, 0);"> </span></font></div><div class=""><font class=""><span class="" style="caret-color: rgb(0, 0, 0);"> # Temporary workaround for PR 196407, which contains the fascinating details.</span></font></div><div class=""><font class=""><span class="" style="caret-color: rgb(0, 0, 0);"> # Don't allow clang to use fpu instructions or registers in kernel modules.</span></font></div></div><div style="caret-color: rgb(0, 0, 0); font-family: Helvetica; font-size: 13px; font-style: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none;" class=""><span class="" style="caret-color: rgb(0, 0, 0);">```</span></div><div style="caret-color: rgb(0, 0, 0); font-family: Helvetica; font-size: 13px; font-style: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none;" class=""><br class=""></div><div style="caret-color: rgb(0, 0, 0); font-family: Helvetica; font-size: 13px; font-style: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none;" class=""><br class=""></div><div style="caret-color: rgb(0, 0, 0); font-family: Helvetica; font-size: 13px; font-style: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none;" class="">As for <a href="https://reviews.freebsd.org/D39638" class="">https://reviews.freebsd.org/D39638</a>, for other platform such as arm, I think the `link_elf_propagate_vnets()` should work if `parse_vnet()` works.</div><div style="caret-color: rgb(0, 0, 0); font-family: Helvetica; font-size: 13px; font-style: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none;" class=""><br class=""></div><div style="caret-color: rgb(0, 0, 0); font-family: Helvetica; font-size: 13px; font-style: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none;" class="">I'll appreciate if someone can test it on platforms those have DYN type kernel modules. </div></div></blockquote><div><br class=""></div><div>Good news on this!</div><div><br class=""></div><div>I've managed to test the change for `link_elf.c` on QEMU RISCV . It works as expected and solid !</div><div><br class=""></div><br class=""><blockquote type="cite" class=""><div class=""><br class="" style="caret-color: rgb(0, 0, 0); font-family: Helvetica; font-size: 13px; font-style: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none;"><blockquote type="cite" class="" style="font-family: Helvetica; font-size: 13px; font-style: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; text-decoration: none;"><div class=""><br class="" style="caret-color: rgb(0, 0, 0); font-family: Menlo-Regular; font-size: 13px; font-style: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none;"><br class="" style="caret-color: rgb(0, 0, 0); font-family: Menlo-Regular; font-size: 13px; font-style: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none;"><blockquote type="cite" class="" style="font-family: Menlo-Regular; font-size: 13px; font-style: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none;"><blockquote type="cite" class=""><br class=""></blockquote><br class="">Hi,<br class=""><br class="">I don't have an answer for you either, but I have seen in the past, loading<br class="">kernel modules behaves a bit like libraries, in the following regard:<br class=""><br class="">If two kernel modules define the same global symbol, then no warning is<br class="">given and the first loaded symbol definition (I think) is used to resolve<br class="">that symbol for all kernel modules, regardless of the prototype. Probably we<br class="">should not allow this. That's why building LINT is a good thing, to avoid<br class="">this issue.<br class=""></blockquote><span class="" style="caret-color: rgb(0, 0, 0); font-family: Menlo-Regular; font-size: 13px; font-style: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none; float: none; display: inline !important;">No, in-kernel linker does not behave this way.</span><br class="" style="caret-color: rgb(0, 0, 0); font-family: Menlo-Regular; font-size: 13px; font-style: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none;"><span class="" style="caret-color: rgb(0, 0, 0); font-family: Menlo-Regular; font-size: 13px; font-style: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none; float: none; display: inline !important;">Modules need to contain explicit reference to all modules they depend upon,</span><br class="" style="caret-color: rgb(0, 0, 0); font-family: Menlo-Regular; font-size: 13px; font-style: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none;"><span class="" style="caret-color: rgb(0, 0, 0); font-family: Menlo-Regular; font-size: 13px; font-style: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none; float: none; display: inline !important;">using the MODULE_DEPEND() macro. Only symbols from the dependencies are</span><br class="" style="caret-color: rgb(0, 0, 0); font-family: Menlo-Regular; font-size: 13px; font-style: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none;"><span class="" style="caret-color: rgb(0, 0, 0); font-family: Menlo-Regular; font-size: 13px; font-style: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none; float: none; display: inline !important;">resolved.</span><br class="" style="caret-color: rgb(0, 0, 0); font-family: Menlo-Regular; font-size: 13px; font-style: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none;"><br class="" style="caret-color: rgb(0, 0, 0); font-family: Menlo-Regular; font-size: 13px; font-style: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none;"><span class="" style="caret-color: rgb(0, 0, 0); font-family: Menlo-Regular; font-size: 13px; font-style: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none; float: none; display: inline !important;">All modules get an implicit reference to kernel.</span><br class="" style="caret-color: rgb(0, 0, 0); font-family: Menlo-Regular; font-size: 13px; font-style: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none;"><br class="" style="caret-color: rgb(0, 0, 0); font-family: Menlo-Regular; font-size: 13px; font-style: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none;"><blockquote type="cite" class="" style="font-family: Menlo-Regular; font-size: 13px; font-style: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none;"><br class="">Even if we don't have C++ support in the FreeBSD kernel, defining symbol<br class="">names the way C++ does for C could be nice for the kernel too, also with<br class="">regards to debugging systems.<br class=""><br class="">Many times when I don't know what is going on, I do like this:<br class=""><br class="">#include <sys/kdb.h><br class=""><br class="">....<br class=""><br class="">if (not too fast or my sysctl debug) {<br class=""> printf("My tracer\n");<br class=""> kdb_backtrace();<br class="">}<br class=""><br class="">Dtrace can also do this, but not during boot. Just track who is calling<br class="">those functions, and you'll probably find the answer to your question!<br class=""><br class="">--HPS<br class=""><br class=""><blockquote type="cite" class=""><br class="">Best regards,<br class="">Zhenlei</blockquote></blockquote></div></blockquote></div></blockquote></div><div class=""><div><br class=""></div></div></body></html>home | help
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