| Message ID | 7h38g0e643.fsf@paris.lan (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Fri, May 23, 2014 at 11:51 AM, Kevin Hilman <khilman@linaro.org> wrote: > Hi Bjorn, > > Bjorn Helgaas <bhelgaas@google.com> writes: > >> On Mon, May 19, 2014 at 02:03:14PM +0100, Alan wrote: >>> From: Alan <alan@linux.intel.com> >>> >>> This is needed for some of the Xeon Phi type systems. >>> >>> Signed-off-by: Alan Cox <alan@linux.intel.com> >> >> I applied this to my pci/resource branch for v3.16. Nikhil >> posted essentially the same patch a couple years ago, so I added >> his signed-off-by and adopted his use of ARRAY_SIZE() to connect the >> "order > 13" test with the aligns[] declaration. > > This patch (with the ARRAY_SIZE changes) has hit next-20140253 (in the > form of commit 272c5a886c57) and according to my bisect, is the cause of > a new boot failure on a 32-bit ARM platform (Marvell Armada 370, > Mirabox, boot log excerpt down below[2].) > > While debugging, I found that Alan's original patch (without the > ARRAY_SIZE change) booted just fine so I started looking closely at the > ARRAY_SIZE() change. After some high-tech printk debugging, I noticed > that order was negative when doing the compare, and found that this hack > got things booting again: > > diff --git a/drivers/pci/setup-bus.c b/drivers/pci/setup-bus.c > index 47482b27fa12..792db3477fd5 100644 > --- a/drivers/pci/setup-bus.c > +++ b/drivers/pci/setup-bus.c > @@ -966,7 +966,7 @@ static int pbus_size_mem(struct pci_bus *bus, unsigned long mask, > /* For bridges size != alignment */ > align = pci_resource_alignment(dev, r); > order = __ffs(align) - 20; > - if (order >= ARRAY_SIZE(aligns)) { > + if (order >= (int)ARRAY_SIZE(aligns)) { > dev_warn(&dev->dev, "disabling BAR %d: %pR " > "(bad alignment %#llx)\n", i, r, > (unsigned long long) align); > > which led me to realize that the ARRAY_SIZE() change converted the >= > into an unsigned compare where before it was a signed one, and as an > unsigned compare, it was always true, resulting in those BARs being > disabled. > > Below is a patch[1] which fixes the problem for me, and attempts a more > detailed description of the problem in the changelog. > > Kevin > > [1] > From 386d39a22e586fc1b060ad18c79247a50f2c0f8c Mon Sep 17 00:00:00 2001 > From: Kevin Hilman <khilman@linaro.org> > Date: Fri, 23 May 2014 10:24:40 -0700 > Subject: [PATCH] PCI: pbus_mem_size(): don't disable small BAR windows > > Since commit 272c5a886c57 (PCI: Support BAR sizes up to 8GB), small > BAR windows get disabled. > > For small BAR sizes, order (as computed by __ffs(align) - 20) may be > negative. If order is negative, when checking if it's >= > ARRAY_SIZE(aligns) will always be true (since the result of > ARRAY_SIZE() is unsigned) and so those BARs will be disabled. > > It doesn't make sense for order to be negative, and the code already > converts it to non-negative later on, so to fix this bug, ensure that > order is non-negative before comapring with ARRAY_SIZE(). > > NOTE: Before commit 272c5a886c57, this worked just fine because order > wasn't compared with ARRAY_SIZE() but with a hard-coded int, so > the resulting signed compare worked fine. > > Signed-off-by: Kevin Hilman <khilman@linaro.org> Ouch, sorry about that. Thanks for your detailed analysis and fix. I folded it into the patch and added a comment in the code. Bjorn > --- > drivers/pci/setup-bus.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/drivers/pci/setup-bus.c b/drivers/pci/setup-bus.c > index 47482b27fa12..a4152566f531 100644 > --- a/drivers/pci/setup-bus.c > +++ b/drivers/pci/setup-bus.c > @@ -966,6 +966,8 @@ static int pbus_size_mem(struct pci_bus *bus, unsigned long mask, > /* For bridges size != alignment */ > align = pci_resource_alignment(dev, r); > order = __ffs(align) - 20; > + if (order < 0) > + order = 0; > if (order >= ARRAY_SIZE(aligns)) { > dev_warn(&dev->dev, "disabling BAR %d: %pR " > "(bad alignment %#llx)\n", i, r, > @@ -974,8 +976,6 @@ static int pbus_size_mem(struct pci_bus *bus, unsigned long mask, > continue; > } > size += r_size; > - if (order < 0) > - order = 0; > /* Exclude ranges with size > align from > calculation of the alignment. */ > if (r_size == align) > -- > 1.9.2 > > > > [2] > [...] > mvebu-pcie pcie-controller.3: PCI host bridge to bus 0000:00 > pci_bus 0000:00: root bus resource [io 0x1000-0xfffff] > pci_bus 0000:00: root bus resource [mem 0xf8000000-0xffdfffff] > pci_bus 0000:00: root bus resource [bus 00-ff] > pci 0000:00:01.0: [11ab:6710] type 01 class 0x060400 > pci 0000:00:02.0: [11ab:6710] type 01 class 0x060400 > PCI: bus0: Fast back to back transfers disabled > pci 0000:00:01.0: bridge configuration invalid ([bus 00-00]), reconfiguring > pci 0000:00:02.0: bridge configuration invalid ([bus 00-00]), reconfiguring > PCI: bus1: Fast back to back transfers enabled > pci_bus 0000:01: busn_res: [bus 01-ff] end is updated to 01 > pci 0000:02:00.0: [1b73:1009] type 00 class 0x0c0330 > pci 0000:02:00.0: reg 0x10: [mem 0x42000000-0x4200ffff 64bit] > pci 0000:02:00.0: reg 0x18: [mem 0x42010000-0x42010fff 64bit] > pci 0000:02:00.0: reg 0x20: [mem 0x42011000-0x42011fff 64bit] > pci 0000:02:00.0: supports D1 > pci 0000:02:00.0: PME# supported from D0 D1 D3hot > PCI: bus2: Fast back to back transfers disabled > pci_bus 0000:02: busn_res: [bus 02-ff] end is updated to 02 > pci 0000:02:00.0: disabling BAR 0: [mem 0x42000000-0x4200ffff 64bit] (bad alignment 0x10000) > pci 0000:02:00.0: disabling BAR 2: [mem 0x42010000-0x42010fff 64bit] (bad alignment 0x1000) > pci 0000:02:00.0: disabling BAR 4: [mem 0x42011000-0x42011fff 64bit] (bad alignment 0x1000) > pci 0000:00:01.0: PCI bridge to [bus 01] > pci 0000:00:02.0: PCI bridge to [bus 02] > Unhandled fault: external abort on non-linefetch (0x1008) at 0xf0080010 > Internal error: : 1008 [#1] SMP ARM > Modules linked in: > CPU: 0 PID: 1 Comm: swapper/0 Not tainted 3.15.0-rc6-next-20140523-08540-gefd7e9bf5d99 #45 > task: ee81ab80 ti: ee83a000 task.ti: ee83a000 > PC is at quirk_usb_early_handoff+0x348/0x7dc > LR is at ioremap_page_range+0xfc/0x1b4 > pc : [<c0297f54>] lr : [<c01886d8>] psr: a0000153 > sp : ee83bd48 ip : c0019a20 fp : c0620964 > r10: 00000100 r9 : ee83bdd0 r8 : 00010000 > r7 : f0080000 r6 : c0607e20 r5 : eeb7a800 r4 : eeb7a800 > r3 : 00000146 r2 : 00000000 r1 : f0090000 r0 : f0080000 > Flags: NzCv IRQs on FIQs off Mode SVC_32 ISA ARM Segment kernel > Control: 10c5387d Table: 00004019 DAC: 00000015 > Process swapper/0 (pid: 1, stack limit = 0xee83a248) > Stack: (0xee83bd48 to 0xee83c000) > bd40: c04428d4 ee83bd80 c062ae30 c053ab4c eeb7a800 c0607e20 > bd60: c053ab4c 0000ffff ee83bdd0 00000100 c0620964 c01bc3a0 00000000 c01eda18 > bd80: eeb7a800 eeb78814 eeb78800 00000001 00010000 c01ab390 eeb7a800 c01ab534 > bda0: eeb7ac00 eeb78e14 eeb78e00 c01ab57c eeb77f80 eeb78e00 ee83be28 c0012d98 > bdc0: f0074000 c0007fc8 feef0000 00000000 eeb77f80 eeb77f80 ee8e3410 c0303450 > bde0: c01be984 c01be9cc ee83be24 00010100 00000002 00000021 00000000 c01bfb68 > be00: eea1a0b8 000007cb 00000065 00000000 eeff2cb4 ee8e3410 ee83be24 10624dd3 > be20: 00000000 eea18210 c05e69c8 00000001 ee83be24 c01be9cc c01be984 00000000 > be40: 00000000 00000000 c0303450 c01bf794 c01be818 00000000 00000000 ee8e3410 > be60: c05e6984 00000000 c05e6984 00000000 00000000 ee83a000 00000000 c01f05b0 > be80: c01f0598 ee8e3410 c062c548 c01ef280 ee8e3410 c05e6984 ee8e3444 00000000 > bea0: c059f558 c01ef434 00000000 c05e6984 c01ef3a8 c01eda80 ee80965c ee8d47b4 > bec0: c05e6984 eeb1a000 c05edcc8 c01eea48 c0505490 c05c6de8 c05e6984 c05e6984 > bee0: c05d5198 eeb70f40 c0607e00 c01efa74 00000000 c05d5198 c05d5198 c0008984 > bf00: c0610304 ee82bc00 c042e950 00000010 c0607e00 c0563398 00000000 c00f5a90 > bf20: 00000000 c05d84a4 60000153 00000001 ef7fce1b c04403d0 000000a2 c00366c0 > bf40: c0562978 00000006 ef7fce26 00000006 c05d8474 c05c6de8 00000006 c05b5f30 > bf60: c0607e00 000000a2 c05b5f3c c058b5a4 00000000 c058bd14 00000006 00000006 > bf80: c058b5a4 00000000 00000000 c0422ffc 00000000 00000000 00000000 00000000 > bfa0: 00000000 c0423004 00000000 c000e5b8 00000000 00000000 00000000 00000000 > bfc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 > bfe0: 00000000 00000000 00000000 00000000 00000013 00000000 00000000 00000000 > [<c0297f54>] (quirk_usb_early_handoff) from [<c01bc3a0>] (pci_fixup_device+0xd4/0x184) > [<c01bc3a0>] (pci_fixup_device) from [<c01ab390>] (pci_bus_add_device+0x14/0x64) > [<c01ab390>] (pci_bus_add_device) from [<c01ab534>] (pci_bus_add_devices+0x3c/0x9c) > [<c01ab534>] (pci_bus_add_devices) from [<c01ab57c>] (pci_bus_add_devices+0x84/0x9c) > [<c01ab57c>] (pci_bus_add_devices) from [<c0012d98>] (pci_common_init_dev+0x184/0x2dc) > [<c0012d98>] (pci_common_init_dev) from [<c01bfb68>] (mvebu_pcie_probe+0x3ac/0x604) > [<c01bfb68>] (mvebu_pcie_probe) from [<c01f05b0>] (platform_drv_probe+0x18/0x48) > [<c01f05b0>] (platform_drv_probe) from [<c01ef280>] (driver_probe_device+0x100/0x228) > [<c01ef280>] (driver_probe_device) from [<c01ef434>] (__driver_attach+0x8c/0x90) > [<c01ef434>] (__driver_attach) from [<c01eda80>] (bus_for_each_dev+0x54/0x88) > [<c01eda80>] (bus_for_each_dev) from [<c01eea48>] (bus_add_driver+0xd4/0x1d0) > [<c01eea48>] (bus_add_driver) from [<c01efa74>] (driver_register+0x78/0xf4) > [<c01efa74>] (driver_register) from [<c0008984>] (do_one_initcall+0x80/0x1b8) > [<c0008984>] (do_one_initcall) from [<c058bd14>] (kernel_init_freeable+0xfc/0x1c8) > [<c058bd14>] (kernel_init_freeable) from [<c0423004>] (kernel_init+0x8/0xec) > [<c0423004>] (kernel_init) from [<c000e5b8>] (ret_from_fork+0x14/0x3c) > Code: e3a02000 ebf5fd27 e2507000 0affff59 (e5973010) > ---[ end trace 20c08b6c6486c9b6 ]--- > Kernel panic - not syncing: Attempted to kill init! exitcode=0x0000000b
diff --git a/drivers/pci/setup-bus.c b/drivers/pci/setup-bus.c index 47482b27fa12..792db3477fd5 100644 --- a/drivers/pci/setup-bus.c +++ b/drivers/pci/setup-bus.c @@ -966,7 +966,7 @@ static int pbus_size_mem(struct pci_bus *bus, unsigned long mask, /* For bridges size != alignment */ align = pci_resource_alignment(dev, r); order = __ffs(align) - 20; - if (order >= ARRAY_SIZE(aligns)) { + if (order >= (int)ARRAY_SIZE(aligns)) { dev_warn(&dev->dev, "disabling BAR %d: %pR " "(bad alignment %#llx)\n", i, r, (unsigned long long) align); which led me to realize that the ARRAY_SIZE() change converted the >= into an unsigned compare where before it was a signed one, and as an unsigned compare, it was always true, resulting in those BARs being disabled. Below is a patch[1] which fixes the problem for me, and attempts a more detailed description of the problem in the changelog. Kevin [1] From 386d39a22e586fc1b060ad18c79247a50f2c0f8c Mon Sep 17 00:00:00 2001 From: Kevin Hilman <khilman@linaro.org> Date: Fri, 23 May 2014 10:24:40 -0700 Subject: [PATCH] PCI: pbus_mem_size(): don't disable small BAR windows Since commit 272c5a886c57 (PCI: Support BAR sizes up to 8GB), small BAR windows get disabled. For small BAR sizes, order (as computed by __ffs(align) - 20) may be negative. If order is negative, when checking if it's >= ARRAY_SIZE(aligns) will always be true (since the result of ARRAY_SIZE() is unsigned) and so those BARs will be disabled. It doesn't make sense for order to be negative, and the code already converts it to non-negative later on, so to fix this bug, ensure that order is non-negative before comapring with ARRAY_SIZE(). NOTE: Before commit 272c5a886c57, this worked just fine because order wasn't compared with ARRAY_SIZE() but with a hard-coded int, so the resulting signed compare worked fine. Signed-off-by: Kevin Hilman <khilman@linaro.org> --- drivers/pci/setup-bus.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/pci/setup-bus.c b/drivers/pci/setup-bus.c index 47482b27fa12..a4152566f531 100644 --- a/drivers/pci/setup-bus.c +++ b/drivers/pci/setup-bus.c @@ -966,6 +966,8 @@ static int pbus_size_mem(struct pci_bus *bus, unsigned long mask, /* For bridges size != alignment */ align = pci_resource_alignment(dev, r); order = __ffs(align) - 20; + if (order < 0) + order = 0; if (order >= ARRAY_SIZE(aligns)) { dev_warn(&dev->dev, "disabling BAR %d: %pR " "(bad alignment %#llx)\n", i, r, @@ -974,8 +976,6 @@ static int pbus_size_mem(struct pci_bus *bus, unsigned long mask, continue; } size += r_size; - if (order < 0) - order = 0; /* Exclude ranges with size > align from calculation of the alignment. */ if (r_size == align)