Can we adopt -Wframe-larger-than=1024 and mark it fatal?
This option is supported by GCC and Clang.
On 31.05.2020 15:55, Jaromír Doleček wrote:
> I think it would make sense to add -Wstack-usage=X to kernel builds.
>
> Either 2KB or 1KB seems to be good limit, not too many offenders
> between 1KB and 2KB so maybe worth it to use 1KB and change them.
>
> I'm sure there would be something similar for LLVM too.
>
> Jaromir
>
> Le dim. 31 mai 2020 à 15:39, Simon Burge <simonb%netbsd.org@localhost> a écrit :
>>
>> matthew green wrote:
>>
>>> glad to see this effort and the clean up already!
>>>
>>> ideally, we can break the kernel build if large stack consumers
>>> are added to the kernel. i'd be OK with it being default on,
>>> with of course a way to skip it, and if necessary it can have
>>> a whitelist of "OK large users."
>>
>> I started to look at -fstack-usage which gives a nice MI way of getting
>> the data instead of parsing MD objdump output, but didn't get any
>> further than the below patch. The find(1) command referenced in the
>> patch gives the following
>>
>> 1008 nfs_serv.c:2181:1:nfsrv_link
>> 1056 procfs_linux.c:422:1:procfs_do_pid_stat
>> 1056 vfs_subr.c:1521:1:vfs_buf_print
>> 1072 dl_print.c:80:1:sdl_print
>> 1104 core_elf32.c:300:1:coredump_getseghdrs_elf32
>> 1104 core_elf32.c:300:1:coredump_getseghdrs_elf64
>> 1104 sys_ptrace_common.c:1595:1:proc_regio
>> 1120 subr_bufq.c:131:1:bufq_alloc
>> 1136 db_lwp.c:64:1:db_lwp_whatis
>> 1152 kern_ktrace.c:1269:1:ktrwrite
>> 1168 uvm_swap.c:768:1:uvm_swap_stats.part.1
>> 1312 nfs_serv.c:1905:1:nfsrv_rename
>> 2112 tty_60.c:68:1:compat_60_ptmget_ioctl
>> 2144 memmem.c:83:14:twoway_memmem
>>
>> Anyone else want to run with adding a bit more to this to do some build
>> failure as mrg@ suggests and documenting for options(4)?
>>
>> Cheers,
>> Simon.
>> --
>> Index: Makefile.kern.inc
>> ===================================================================
>> RCS file: /cvsroot/src/sys/conf/Makefile.kern.inc,v
>> retrieving revision 1.270
>> diff -d -p -u -r1.270 Makefile.kern.inc
>> --- Makefile.kern.inc 21 May 2020 18:44:19 -0000 1.270
>> +++ Makefile.kern.inc 31 May 2020 13:34:13 -0000
>> @@ -104,6 +104,11 @@ CFLAGS+= -ffreestanding -fno-zero-initia
>> CFLAGS+= ${${ACTIVE_CC} == "gcc":? -fno-delete-null-pointer-checks :}
>> CFLAGS+= ${DEBUG} ${COPTS}
>> AFLAGS+= -D_LOCORE -Wa,--fatal-warnings
>> +.if defined(KERN_STACK_USAGE)
>> +# example usage to find largest stack users in kernel compile directory:
>> +# find . -name \*.su | xargs awk '{ printf "%6d %s\n", $2, $1 }' | sort +1n
>> +CFLAGS+= -fstack-usage
>> +.endif
>>
>> # XXX
>> .if defined(HAVE_GCC) || defined(HAVE_LLVM)
>> @@ -338,8 +343,8 @@ ${_s:T:R}.o: ${_s}
>> .if !target(__CLEANKERNEL)
>> __CLEANKERNEL: .USE
>> ${_MKMSG} "${.TARGET}ing the kernel objects"
>> - rm -f ${KERNELS} *.map eddep tags *.[io] *.ko *.ln [a-z]*.s vers.c \
>> - [Ee]rrs linterrs makelinks assym.h.tmp assym.h \
>> + rm -f ${KERNELS} *.map *.[io] *.ko *.ln [a-z]*.s *.su vers.c \
>> + eddep tags [Ee]rrs linterrs makelinks assym.h.tmp assym.h \
>> ${EXTRA_KERNELS} ${EXTRA_CLEAN}
>> .endif
>>
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