linux-kernel - Re: [PATCH v2 3/4] x86/PCI: Tidy E820 removal messages

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20221209203428.GA1721600@bhelgaas>
Date:   Fri, 9 Dec 2022 14:34:28 -0600
From:   Bjorn Helgaas <helgaas@...nel.org>
To:     Andy Shevchenko <andriy.shevchenko@...el.com>
Cc:     linux-pci@...r.kernel.org, Hans de Goede <hdegoede@...hat.com>,
        Florent DELAHAYE <kernelorg@...ead.fr>,
        Konrad J Hambrick <kjhambrick@...il.com>,
        Matt Hansen <2lprbe78@...k.com>,
        Benoit Grégoire <benoitg@...us.ca>,
        Nicholas Johnson <nicholas.johnson-opensource@...look.com.au>,
        Mika Westerberg <mika.westerberg@...ux.intel.com>,
        Werner Sembach <wse@...edocomputers.com>,
        mumblingdrunkard@...tonmail.com, linux-kernel@...r.kernel.org,
        Bjorn Helgaas <bhelgaas@...gle.com>
Subject: Re: [PATCH v2 3/4] x86/PCI: Tidy E820 removal messages

On Fri, Dec 09, 2022 at 08:42:06PM +0200, Andy Shevchenko wrote:
> On Thu, Dec 08, 2022 at 01:03:40PM -0600, Bjorn Helgaas wrote:
> > From: Bjorn Helgaas <bhelgaas@...gle.com>
> > 
> > These messages:
> > 
> >   clipped [mem size 0x00000000 64bit] to [mem size 0xfffffffffffa0000 64bit] for e820 entry [mem 0x0009f000-0x000fffff]
> > 
> > aren't as useful as they could be because (a) the resource is often
> > IORESOURCE_UNSET, so we print the size instead of the start/end and (b) we
> > print the available resource even if it is empty after removing the E820
> > entry.
> > 
> > Print the available space by hand to avoid the IORESOURCE_UNSET problem and
> > only if it's non-empty.  No functional change intended.
> 
> ...
> 
> > +			if (avail->end > avail->start)
> > +				pr_info("resource: remaining [mem %#010llx-%#010llx] available\n",
> > +					(unsigned long long) avail->start,
> > +					(unsigned long long) avail->end);
> 
> Is there any point why we do not use %pa for resource_size_t parameters?

Only my ignorance :)  Thanks for pointing that out; I changed it to
this and added a comment about why:


--- a/arch/x86/kernel/resource.c
+++ b/arch/x86/kernel/resource.c
@@ -42,8 +42,16 @@ static void remove_e820_regions(struct resource *avail)
 
 		resource_clip(avail, e820_start, e820_end);
 		if (orig.start != avail->start || orig.end != avail->end) {
-			pr_info("clipped %pR to %pR for e820 entry [mem %#010Lx-%#010Lx]\n",
-				 &orig, avail, e820_start, e820_end);
+			pr_info("resource: avoiding allocation from e820 entry [mem %#010Lx-%#010Lx]\n",
+				e820_start, e820_end);
+			if (avail->end > avail->start)
+				/*
+				 * Use %pa instead of %pR because "avail"
+				 * is typically IORESOURCE_UNSET, so %pR
+				 * shows the size instead of addresses.
+				 */
+				pr_info("resource: remaining [mem %pa-%pa] available\n",
+					&avail->start, &avail->end);
 			orig = *avail;
 		}
 	}