1. 07 Nov, 2017 1 commit
    • Chris Wilson's avatar
      drm/i915: Deconstruct struct sgt_dma initialiser · 5684514b
      Chris Wilson authored
      gcc-4.4 complains about:
      
      	struct sgt_dma iter = {
      		.sg = vma->pages->sgl,
      		.dma = sg_dma_address(iter.sg),
      		.max = iter.dma + iter.sg->length,
      	};
      
      drivers/gpu/drm/i915/i915_gem_gtt.c: In function ‘gen8_ppgtt_insert_4lvl’:
      drivers/gpu/drm/i915/i915_gem_gtt.c:938: error: ‘iter.sg’ is used uninitialized in this function
      drivers/gpu/drm/i915/i915_gem_gtt.c:939: error: ‘iter.dma’ is used uninitialized in this function
      
      and worse generates invalid code that triggers a GPF:
      
      BUG: unable to handle kernel NULL pointer dereference at 0000000000000010
      IP: gen8_ppgtt_insert_4lvl+0x1b/0x1e0 [i915]
      PGD 0
      Oops: 0000 [#1] SMP
      Modules linked in: snd_aloop nf_conntrack_ipv6 nf_defrag_ipv6 nf_log_ipv6 ip6table_filter ip6_tables ctr ccm xt_state nf_log_ipv4
      nf_log_common xt_LOG xt_limit xt_recent xt_owner xt_addrtype iptable_filter ipt_MASQUERADE nf_nat_masquerade_ipv4 iptable_nat
      nf_conntrack_ipv4 nf_defrag_ipv4 nf_nat_ipv4 nf_nat nf_conntrack libcrc32c ip_tables dm_mod vhost_net macvtap macvlan vhost tun kvm_intel kvm
      irqbypass uas usb_storage hid_multitouch btusb btrtl uvcvideo videobuf2_v4l2 videobuf2_core videodev media videobuf2_vmalloc videobuf2_memops
      sg ppdev dell_wmi sparse_keymap mei_wdt sd_mod iTCO_wdt iTCO_vendor_support rtsx_pci_ms memstick rtsx_pci_sdmmc mmc_core dell_smm_hwmon hwmon
      dell_laptop dell_smbios dcdbas joydev input_leds hci_uart btintel btqca btbcm bluetooth parport_pc parport i2c_hid
        intel_lpss_acpi intel_lpss pcspkr wmi int3400_thermal acpi_thermal_rel dell_rbtn mei_me mei snd_hda_codec_hdmi snd_hda_codec_realtek
      snd_hda_codec_generic ahci libahci acpi_pad xhci_pci xhci_hcd snd_hda_intel snd_hda_codec snd_hda_core snd_hwdep snd_seq snd_seq_device
      snd_pcm snd_timer snd soundcore int3403_thermal arc4 e1000e ptp pps_core i2c_i801 iwlmvm mac80211 rtsx_pci iwlwifi cfg80211 rfkill
      intel_pch_thermal processor_thermal_device int340x_thermal_zone intel_soc_dts_iosf i915 video fjes
      CPU: 2 PID: 2408 Comm: X Not tainted 4.10.0-rc5+ #1
      Hardware name: Dell Inc. Latitude E7470/0T6HHJ, BIOS 1.11.3 11/09/2016
      task: ffff880219fe4740 task.stack: ffffc90005f98000
      RIP: 0010:gen8_ppgtt_insert_4lvl+0x1b/0x1e0 [i915]
      RSP: 0018:ffffc90005f9b8c8 EFLAGS: 00010246
      RAX: 0000000000000000 RBX: ffff8802167d8000 RCX: 0000000000000001
      RDX: 00000000ffff7000 RSI: ffff880219f94140 RDI: ffff880228444000
      RBP: ffffc90005f9b948 R08: 0000000000000000 R09: 0000000000000000
      R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000080
      R13: 0000000000000001 R14: ffffc90005f9bcd7 R15: ffff88020c9a83c0
      FS:  00007fb53e1ee920(0000) GS:ffff88024dd00000(0000) knlGS:0000000000000000
      CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
      CR2: 0000000000000010 CR3: 000000022ef95000 CR4: 00000000003406e0
      DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
      DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
      Call Trace:
        ppgtt_bind_vma+0x40/0x50 [i915]
        i915_vma_bind+0xcb/0x1c0 [i915]
        __i915_vma_do_pin+0x6e/0xd0 [i915]
        i915_gem_execbuffer_reserve_vma+0x162/0x1d0 [i915]
        i915_gem_execbuffer_reserve+0x4fc/0x510 [i915]
        ? __kmalloc+0x134/0x250
        ? i915_gem_wait_for_error+0x25/0x100 [i915]
        ? i915_gem_wait_for_error+0x25/0x100 [i915]
        i915_gem_do_execbuffer+0x2df/0xa00 [i915]
        ? drm_malloc_gfp.clone.0+0x42/0x80 [i915]
        ? path_put+0x22/0x30
        ? __check_object_size+0x62/0x1f0
        ? terminate_walk+0x44/0x90
        i915_gem_execbuffer2+0x95/0x1e0 [i915]
        drm_ioctl+0x243/0x490
        ? handle_pte_fault+0x1d7/0x220
        ? i915_gem_do_execbuffer+0xa00/0xa00 [i915]
        ? handle_mm_fault+0x10d/0x2a0
        vfs_ioctl+0x18/0x30
        do_vfs_ioctl+0x14b/0x3f0
        SyS_ioctl+0x92/0xa0
        entry_SYSCALL_64_fastpath+0x1a/0xa9
      RIP: 0033:0x7fb53b4fcb77
      RSP: 002b:00007ffe0c572898 EFLAGS: 00003246 ORIG_RAX: 0000000000000010
      RAX: ffffffffffffffda RBX: 00007fb53e17c038 RCX: 00007fb53b4fcb77
      RDX: 00007ffe0c572900 RSI: 0000000040406469 RDI: 000000000000000b
      RBP: 00007fb5376d67e0 R08: 0000000000000000 R09: 0000000000000000
      R10: 0000000000000028 R11: 0000000000003246 R12: 0000000000000000
      R13: 0000000000000000 R14: 000055eecb314d00 R15: 000055eecb315460
      Code: 0f 84 5d ff ff ff eb a2 0f 1f 84 00 00 00 00 00 55 48 89 e5 41 57 41 56 41 55 41 54 53 48 83 ec 58 0f 1f 44 00 00 31 c0 89 4d b0 <4c>
      8b 60 10 44 8b 70 0c 48 89 d0 4c 8b 2e 48 c1 e8 27 25 ff 01
      RIP: gen8_ppgtt_insert_4lvl+0x1b/0x1e0 [i915] RSP: ffffc90005f9b8c8
      CR2: 0000000000000010
      
      Recent gccs, such as 4.9, 6.3 or 7.2, do not generate the warning nor do
      they explode on use. If we manually create the struct using locals from
      the stack, this should eliminate this issue, and does not alter code
      generation with gcc-7.2.
      
      Fixes: 894ccebe ("drm/i915: Micro-optimise gen8_ppgtt_insert_entries()")
      Reported-by: default avatarKelly French <kfrench@federalhill.net>
      Signed-off-by: default avatarChris Wilson <chris@chris-wilson.co.uk>
      Cc: Kelly French <kfrench@federalhill.net>
      Cc: Mika Kuoppala <mika.kuoppala@intel.com>
      Link: https://patchwork.freedesktop.org/patch/msgid/20171106211128.12538-1-chris@chris-wilson.co.ukTested-by: default avatarKelly French <kfrench@federalhill.net>
      Reviewed-by: default avatarTvrtko Ursulin <tvrtko.ursulin@intel.com>
      5684514b
  2. 06 Nov, 2017 8 commits
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