| Message ID | 20210212153953.4582-4-andrew.cooper3@citrix.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | tools: Support to use abi-dumper on libraries | expand |
Hi Andrew, On 12/02/2021 15:39, Andrew Cooper wrote: > Various version of gcc, when compiling with -Og, complain: > > xg_dom_arm.c: In function 'meminit': > xg_dom_arm.c:420:19: error: 'p2m_size' may be used uninitialized in this function [-Werror=maybe-uninitialized] > 420 | dom->p2m_size = p2m_size; > | ~~~~~~~~~~~~~~^~~~~~~~~~ > > Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com> This was reported nearly 3 years ago (see [1]) and it is pretty sad this was never merged :(. > --- > CC: Ian Jackson <iwj@xenproject.org> > CC: Wei Liu <wl@xen.org> > CC: Stefano Stabellini <sstabellini@kernel.org> > CC: Julien Grall <julien@xen.org> > > Julien/Stefano: I can't work out how this variable is supposed to work, and > the fact that it isn't a straight accumulation across the RAM banks looks > suspect. It looks buggy, but the P2M is never used on Arm. In fact, you sent a patch a year ago to drop it (see [2]). It would be nice to revive it. > --- > tools/libs/guest/xg_dom_arm.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/tools/libs/guest/xg_dom_arm.c b/tools/libs/guest/xg_dom_arm.c > index 94948d2b20..f1b8d06f75 100644 > --- a/tools/libs/guest/xg_dom_arm.c > +++ b/tools/libs/guest/xg_dom_arm.c > @@ -373,7 +373,7 @@ static int meminit(struct xc_dom_image *dom) > const uint64_t modsize = dtb_size + ramdisk_size; > const uint64_t ram128mb = bankbase[0] + (128<<20); > > - xen_pfn_t p2m_size; > + xen_pfn_t p2m_size = 0; > uint64_t bank0end; > > assert(dom->rambase_pfn << XC_PAGE_SHIFT == bankbase[0]); > If your original series is too risky for 4.15, I would consider to remote p2m_size completely and always 0 dom->p2m_size. Cheers, [1] https://lore.kernel.org/xen-devel/20180314123203.30646-1-wei.liu2@citrix.com/ [2] https://patchwork.kernel.org/project/xen-devel/patch/20191217201550.15864-3-andrew.cooper3@citrix.com/
On 12/02/2021 15:55, Julien Grall wrote: > Hi Andrew, > > On 12/02/2021 15:39, Andrew Cooper wrote: >> Various version of gcc, when compiling with -Og, complain: >> >> xg_dom_arm.c: In function 'meminit': >> xg_dom_arm.c:420:19: error: 'p2m_size' may be used uninitialized >> in this function [-Werror=maybe-uninitialized] >> 420 | dom->p2m_size = p2m_size; >> | ~~~~~~~~~~~~~~^~~~~~~~~~ >> >> Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com> > > This was reported nearly 3 years ago (see [1]) and it is pretty sad > this was never merged :(. :( We've got far too many patches which fall through the cracks like this. > >> --- >> CC: Ian Jackson <iwj@xenproject.org> >> CC: Wei Liu <wl@xen.org> >> CC: Stefano Stabellini <sstabellini@kernel.org> >> CC: Julien Grall <julien@xen.org> >> >> Julien/Stefano: I can't work out how this variable is supposed to >> work, and >> the fact that it isn't a straight accumulation across the RAM banks >> looks >> suspect. > > It looks buggy, but the P2M is never used on Arm. In fact, you sent a > patch a year ago to drop it (see [2]). It would be nice to revive it. That series was committed more than a year ago - ee21f10d70^..97e34ad22d - and tbh, I'd forgotten about it. In light of that, I think I'll just delete the p2m_size references here. It's easy to prove correctness via inspection, and removes a dubious construct entirely. ~Andrew
diff --git a/tools/libs/guest/xg_dom_arm.c b/tools/libs/guest/xg_dom_arm.c index 94948d2b20..f1b8d06f75 100644 --- a/tools/libs/guest/xg_dom_arm.c +++ b/tools/libs/guest/xg_dom_arm.c @@ -373,7 +373,7 @@ static int meminit(struct xc_dom_image *dom) const uint64_t modsize = dtb_size + ramdisk_size; const uint64_t ram128mb = bankbase[0] + (128<<20); - xen_pfn_t p2m_size; + xen_pfn_t p2m_size = 0; uint64_t bank0end; assert(dom->rambase_pfn << XC_PAGE_SHIFT == bankbase[0]);
Various version of gcc, when compiling with -Og, complain: xg_dom_arm.c: In function 'meminit': xg_dom_arm.c:420:19: error: 'p2m_size' may be used uninitialized in this function [-Werror=maybe-uninitialized] 420 | dom->p2m_size = p2m_size; | ~~~~~~~~~~~~~~^~~~~~~~~~ Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com> --- CC: Ian Jackson <iwj@xenproject.org> CC: Wei Liu <wl@xen.org> CC: Stefano Stabellini <sstabellini@kernel.org> CC: Julien Grall <julien@xen.org> Julien/Stefano: I can't work out how this variable is supposed to work, and the fact that it isn't a straight accumulation across the RAM banks looks suspect. --- tools/libs/guest/xg_dom_arm.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)