Remove feature(test) from most samples.
#175
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Signed-off-by: Miguel Ojeda <[email protected]>
alex
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Apr 11, 2021
ojeda
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If a relocatable kernel is loaded at a non-zero address and told not to relocate to zero (kdump or RELOCATABLE_TEST), the mapping of the interrupt code at zero is left with RWX permissions. That is a security weakness, and leads to a warning at boot if CONFIG_DEBUG_WX is enabled: powerpc/mm: Found insecure W+X mapping at address 00000000056435bc/0xc000000000000000 WARNING: CPU: 1 PID: 1 at arch/powerpc/mm/ptdump/ptdump.c:193 note_page+0x484/0x4c0 CPU: 1 PID: 1 Comm: swapper/0 Not tainted 6.2.0-rc1-00001-g8ae8e98aea82-dirty #175 Hardware name: IBM pSeries (emulated by qemu) POWER9 (raw) 0x4e1202 0xf000005 of:SLOF,git-dd0dca hv:linux,kvm pSeries NIP: c0000000004a1c34 LR: c0000000004a1c30 CTR: 0000000000000000 REGS: c000000003503770 TRAP: 0700 Not tainted (6.2.0-rc1-00001-g8ae8e98aea82-dirty) MSR: 8000000002029033 <SF,VEC,EE,ME,IR,DR,RI,LE> CR: 24000220 XER: 00000000 CFAR: c000000000545a58 IRQMASK: 0 ... NIP note_page+0x484/0x4c0 LR note_page+0x480/0x4c0 Call Trace: note_page+0x480/0x4c0 (unreliable) ptdump_pmd_entry+0xc8/0x100 walk_pgd_range+0x618/0xab0 walk_page_range_novma+0x74/0xc0 ptdump_walk_pgd+0x98/0x170 ptdump_check_wx+0x94/0x100 mark_rodata_ro+0x30/0x70 kernel_init+0x78/0x1a0 ret_from_kernel_thread+0x5c/0x64 The fix has two parts. Firstly the pages from zero up to the end of interrupts need to be marked read-only, so that they are left with R-X permissions. Secondly the mapping logic needs to be taught to ensure there is a page boundary at the end of the interrupt region, so that the permission change only applies to the interrupt text, and not the region following it. Fixes: c55d7b5 ("powerpc: Remove STRICT_KERNEL_RWX incompatibility with RELOCATABLE") Reported-by: Sachin Sant <[email protected]> Tested-by: Sachin Sant <[email protected]> Signed-off-by: Michael Ellerman <[email protected]> Link: https://lore.kernel.org/r/[email protected]
ojeda
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May 6, 2025
Commit <5518f239aff1> ("iommu/vt-d: Move scalable mode ATS enablement to
probe path") changed the PCI ATS enablement logic to run earlier,
specifically before the default domain attachment.
On some client platforms, this change resulted in boot failures, causing
the kernel to panic with the following message and call trace:
Kernel panic - not syncing: DMAR hardware is malfunctioning
CPU: 0 UID: 0 PID: 1 Comm: swapper/0 Not tainted 6.14.0-rc3+ #175
Call Trace:
<TASK>
dump_stack_lvl+0x6f/0xb0
dump_stack+0x10/0x16
panic+0x10a/0x2b7
iommu_enable_translation.cold+0xc/0xc
intel_iommu_init+0xe39/0xec0
? trace_hardirqs_on+0x1e/0xd0
? __pfx_pci_iommu_init+0x10/0x10
pci_iommu_init+0xd/0x40
do_one_initcall+0x5b/0x390
kernel_init_freeable+0x26d/0x2b0
? __pfx_kernel_init+0x10/0x10
kernel_init+0x15/0x120
ret_from_fork+0x35/0x60
? __pfx_kernel_init+0x10/0x10
ret_from_fork_asm+0x1a/0x30
RIP: 1f0f:0x0
Code: Unable to access opcode bytes at 0xffffffffffffffd6.
RSP: 0000:0000000000000000 EFLAGS: 841f0f2e66 ORIG_RAX:
1f0f2e6600000000
RAX: 0000000000000000 RBX: 1f0f2e6600000000 RCX:
2e66000000000084
RDX: 0000000000841f0f RSI: 000000841f0f2e66 RDI:
00841f0f2e660000
RBP: 00841f0f2e660000 R08: 00841f0f2e660000 R09:
000000841f0f2e66
R10: 0000000000841f0f R11: 2e66000000000084 R12:
000000841f0f2e66
R13: 0000000000841f0f R14: 2e66000000000084 R15:
1f0f2e6600000000
</TASK>
---[ end Kernel panic - not syncing: DMAR hardware is malfunctioning ]---
Fix this by reverting the timing change for ATS enablement introduced by
the offending commit and restoring the previous behavior.
Fixes: 5518f23 ("iommu/vt-d: Move scalable mode ATS enablement to probe path")
Reported-by: Jarkko Nikula <[email protected]>
Closes: https://lore.kernel.org/linux-iommu/[email protected]/
Signed-off-by: Lu Baolu <[email protected]>
Tested-by: Jarkko Nikula <[email protected]>
Reviewed-by: Kevin Tian <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Joerg Roedel <[email protected]>
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Signed-off-by: Miguel Ojeda [email protected]