linux.git/arch/powerpc/kernel, branch v6.6 Linux kernel source tree powerpc/mm: Fix boot crash with FLATMEM 2023-10-23T11:50:15+00:00 Michael Ellerman mpe@ellerman.id.au 2023-10-23T11:25:00+00:00 daa9ada2093ed23d52b4c1fe6e13cf78f55cc85f Erhard reported that his G5 was crashing with v6.6-rc kernels: mpic: Setting up HT PICs workarounds for U3/U4 BUG: Unable to handle kernel data access at 0xfeffbb62ffec65fe Faulting instruction address: 0xc00000000005dc40 Oops: Kernel access of bad area, sig: 11 [#1] BE PAGE_SIZE=4K MMU=Hash SMP NR_CPUS=2 PowerMac Modules linked in: CPU: 0 PID: 0 Comm: swapper/0 Tainted: G T 6.6.0-rc3-PMacGS #1 Hardware name: PowerMac11,2 PPC970MP 0x440101 PowerMac NIP: c00000000005dc40 LR: c000000000066660 CTR: c000000000007730 REGS: c0000000022bf510 TRAP: 0380 Tainted: G T (6.6.0-rc3-PMacGS) MSR: 9000000000001032 <SF,HV,ME,IR,DR,RI> CR: 44004242 XER: 00000000 IRQMASK: 3 GPR00: 0000000000000000 c0000000022bf7b0 c0000000010c0b00 00000000000001ac GPR04: 0000000003c80000 0000000000000300 c0000000f20001ae 0000000000000300 GPR08: 0000000000000006 feffbb62ffec65ff 0000000000000001 0000000000000000 GPR12: 9000000000001032 c000000002362000 c000000000f76b80 000000000349ecd8 GPR16: 0000000002367ba8 0000000002367f08 0000000000000006 0000000000000000 GPR20: 00000000000001ac c000000000f6f920 c0000000022cd985 000000000000000c GPR24: 0000000000000300 00000003b0a3691d c0003e008030000e 0000000000000000 GPR28: c00000000000000c c0000000f20001ee feffbb62ffec65fe 00000000000001ac NIP hash_page_do_lazy_icache+0x50/0x100 LR __hash_page_4K+0x420/0x590 Call Trace: hash_page_mm+0x364/0x6f0 do_hash_fault+0x114/0x2b0 data_access_common_virt+0x198/0x1f0 --- interrupt: 300 at mpic_init+0x4bc/0x10c4 NIP: c000000002020a5c LR: c000000002020a04 CTR: 0000000000000000 REGS: c0000000022bf9f0 TRAP: 0300 Tainted: G T (6.6.0-rc3-PMacGS) MSR: 9000000000001032 <SF,HV,ME,IR,DR,RI> CR: 24004248 XER: 00000000 DAR: c0003e008030000e DSISR: 40000000 IRQMASK: 1 ... NIP mpic_init+0x4bc/0x10c4 LR mpic_init+0x464/0x10c4 --- interrupt: 300 pmac_setup_one_mpic+0x258/0x2dc pmac_pic_init+0x28c/0x3d8 init_IRQ+0x90/0x140 start_kernel+0x57c/0x78c start_here_common+0x1c/0x20 A bisect pointed to the breakage beginning with commit 9fee28baa601 ("powerpc: implement the new page table range API"). Analysis of the oops pointed to a struct page with a corrupted compound_head being loaded via page_folio() -> _compound_head() in hash_page_do_lazy_icache(). The access by the mpic code is to an MMIO address, so the expectation is that the struct page for that address would be initialised by init_unavailable_range(), as pointed out by Aneesh. Instrumentation showed that was not the case, which eventually lead to the realisation that pfn_valid() was returning false for that address, causing the struct page to not be initialised. Because the system is using FLATMEM, the version of pfn_valid() in memory_model.h is used: static inline int pfn_valid(unsigned long pfn) { ... return pfn >= pfn_offset && (pfn - pfn_offset) < max_mapnr; } Which relies on max_mapnr being initialised. Early in boot max_mapnr is zero meaning no PFNs are valid. max_mapnr is initialised in mem_init() called via: start_kernel() mm_core_init() # init/main.c:928 mem_init() But that is too late for the usage in init_unavailable_range() called via: start_kernel() setup_arch() # init/main.c:893 paging_init() free_area_init() init_unavailable_range() Although max_mapnr is currently set in mem_init(), the value is actually already available much earlier, as soon as mem_topology_setup() has completed, which is also before paging_init() is called. So move the initialisation there, which causes paging_init() to correctly initialise the struct page and fixes the bug. This bug seems to have been lurking for years, but went unnoticed because the pre-folio code was inspecting the uninitialised page->flags but not dereferencing it. Thanks to Erhard and Aneesh for help debugging. Reported-by: Erhard Furtner <erhard_f@mailbox.org> Closes: https://lore.kernel.org/all/20230929132750.3cd98452@yea/ Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://msgid.link/20231023112500.1550208-1-mpe@ellerman.id.au 
Erhard reported that his G5 was crashing with v6.6-rc kernels:

  mpic: Setting up HT PICs workarounds for U3/U4
  BUG: Unable to handle kernel data access at 0xfeffbb62ffec65fe
  Faulting instruction address: 0xc00000000005dc40
  Oops: Kernel access of bad area, sig: 11 [#1]
  BE PAGE_SIZE=4K MMU=Hash SMP NR_CPUS=2 PowerMac
  Modules linked in:
  CPU: 0 PID: 0 Comm: swapper/0 Tainted: G                T  6.6.0-rc3-PMacGS #1
  Hardware name: PowerMac11,2 PPC970MP 0x440101 PowerMac
  NIP:  c00000000005dc40 LR: c000000000066660 CTR: c000000000007730
  REGS: c0000000022bf510 TRAP: 0380   Tainted: G                T (6.6.0-rc3-PMacGS)
  MSR:  9000000000001032 <SF,HV,ME,IR,DR,RI>  CR: 44004242  XER: 00000000
  IRQMASK: 3
  GPR00: 0000000000000000 c0000000022bf7b0 c0000000010c0b00 00000000000001ac
  GPR04: 0000000003c80000 0000000000000300 c0000000f20001ae 0000000000000300
  GPR08: 0000000000000006 feffbb62ffec65ff 0000000000000001 0000000000000000
  GPR12: 9000000000001032 c000000002362000 c000000000f76b80 000000000349ecd8
  GPR16: 0000000002367ba8 0000000002367f08 0000000000000006 0000000000000000
  GPR20: 00000000000001ac c000000000f6f920 c0000000022cd985 000000000000000c
  GPR24: 0000000000000300 00000003b0a3691d c0003e008030000e 0000000000000000
  GPR28: c00000000000000c c0000000f20001ee feffbb62ffec65fe 00000000000001ac
  NIP hash_page_do_lazy_icache+0x50/0x100
  LR  __hash_page_4K+0x420/0x590
  Call Trace:
    hash_page_mm+0x364/0x6f0
    do_hash_fault+0x114/0x2b0
    data_access_common_virt+0x198/0x1f0
  --- interrupt: 300 at mpic_init+0x4bc/0x10c4
  NIP:  c000000002020a5c LR: c000000002020a04 CTR: 0000000000000000
  REGS: c0000000022bf9f0 TRAP: 0300   Tainted: G                T (6.6.0-rc3-PMacGS)
  MSR:  9000000000001032 <SF,HV,ME,IR,DR,RI>  CR: 24004248  XER: 00000000
  DAR: c0003e008030000e DSISR: 40000000 IRQMASK: 1
  ...
  NIP mpic_init+0x4bc/0x10c4
  LR  mpic_init+0x464/0x10c4
  --- interrupt: 300
    pmac_setup_one_mpic+0x258/0x2dc
    pmac_pic_init+0x28c/0x3d8
    init_IRQ+0x90/0x140
    start_kernel+0x57c/0x78c
    start_here_common+0x1c/0x20

A bisect pointed to the breakage beginning with commit 9fee28baa601 ("powerpc:
implement the new page table range API").

Analysis of the oops pointed to a struct page with a corrupted
compound_head being loaded via page_folio() -> _compound_head() in
hash_page_do_lazy_icache().

The access by the mpic code is to an MMIO address, so the expectation
is that the struct page for that address would be initialised by
init_unavailable_range(), as pointed out by Aneesh.

Instrumentation showed that was not the case, which eventually lead to
the realisation that pfn_valid() was returning false for that address,
causing the struct page to not be initialised.

Because the system is using FLATMEM, the version of pfn_valid() in
memory_model.h is used:

static inline int pfn_valid(unsigned long pfn)
{
	...
	return pfn >= pfn_offset && (pfn - pfn_offset) < max_mapnr;
}

Which relies on max_mapnr being initialised. Early in boot max_mapnr is
zero meaning no PFNs are valid.

max_mapnr is initialised in mem_init() called via:

  start_kernel()
    mm_core_init()  # init/main.c:928
      mem_init()

But that is too late for the usage in init_unavailable_range() called via:

  start_kernel()
    setup_arch()    # init/main.c:893
      paging_init()
        free_area_init()
          init_unavailable_range()

Although max_mapnr is currently set in mem_init(), the value is actually
already available much earlier, as soon as mem_topology_setup() has
completed, which is also before paging_init() is called. So move the
initialisation there, which causes paging_init() to correctly initialise
the struct page and fixes the bug.

This bug seems to have been lurking for years, but went unnoticed
because the pre-folio code was inspecting the uninitialised page->flags
but not dereferencing it.

Thanks to Erhard and Aneesh for help debugging.

Reported-by: Erhard Furtner <erhard_f@mailbox.org>
Closes: https://lore.kernel.org/all/20230929132750.3cd98452@yea/
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20231023112500.1550208-1-mpe@ellerman.id.au
powerpc/47x: Fix 47x syscall return crash 2023-10-10T22:31:26+00:00 Michael Ellerman mpe@ellerman.id.au 2023-10-10T11:47:50+00:00 f0eee815babed70a749d2496a7678be5b45b4c14 Eddie reported that newer kernels were crashing during boot on his 476 FSP2 system: kernel tried to execute user page (b7ee2000) - exploit attempt? (uid: 0) BUG: Unable to handle kernel instruction fetch Faulting instruction address: 0xb7ee2000 Oops: Kernel access of bad area, sig: 11 [#1] BE PAGE_SIZE=4K FSP-2 Modules linked in: CPU: 0 PID: 61 Comm: mount Not tainted 6.1.55-d23900f.ppcnf-fsp2 #1 Hardware name: ibm,fsp2 476fpe 0x7ff520c0 FSP-2 NIP:  b7ee2000 LR: 8c008000 CTR: 00000000 REGS: bffebd83 TRAP: 0400   Not tainted (6.1.55-d23900f.ppcnf-fs p2) MSR:  00000030 <IR,DR>  CR: 00001000  XER: 20000000 GPR00: c00110ac bffebe63 bffebe7e bffebe88 8c008000 00001000 00000d12 b7ee2000 GPR08: 00000033 00000000 00000000 c139df10 48224824 1016c314 10160000 00000000 GPR16: 10160000 10160000 00000008 00000000 10160000 00000000 10160000 1017f5b0 GPR24: 1017fa50 1017f4f0 1017fa50 1017f740 1017f630 00000000 00000000 1017f4f0 NIP [b7ee2000] 0xb7ee2000 LR [8c008000] 0x8c008000 Call Trace: Instruction dump: XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX ---[ end trace 0000000000000000 ]--- The problem is in ret_from_syscall where the check for icache_44x_need_flush is done. When the flush is needed the code jumps out-of-line to do the flush, and then intends to jump back to continue the syscall return. However the branch back to label 1b doesn't return to the correct location, instead branching back just prior to the return to userspace, causing bogus register values to be used by the rfi. The breakage was introduced by commit 6f76a01173cc ("powerpc/syscall: implement system call entry/exit logic in C for PPC32") which inadvertently removed the "1" label and reused it elsewhere. Fix it by adding named local labels in the correct locations. Note that the return label needs to be outside the ifdef so that CONFIG_PPC_47x=n compiles. Fixes: 6f76a01173cc ("powerpc/syscall: implement system call entry/exit logic in C for PPC32") Cc: stable@vger.kernel.org # v5.12+ Reported-by: Eddie James <eajames@linux.ibm.com> Tested-by: Eddie James <eajames@linux.ibm.com> Link: https://lore.kernel.org/linuxppc-dev/fdaadc46-7476-9237-e104-1d2168526e72@linux.ibm.com/ Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu> Link: https://msgid.link/20231010114750.847794-1-mpe@ellerman.id.au 
Eddie reported that newer kernels were crashing during boot on his 476
FSP2 system:

  kernel tried to execute user page (b7ee2000) - exploit attempt? (uid: 0)
  BUG: Unable to handle kernel instruction fetch
  Faulting instruction address: 0xb7ee2000
  Oops: Kernel access of bad area, sig: 11 [#1]
  BE PAGE_SIZE=4K FSP-2
  Modules linked in:
  CPU: 0 PID: 61 Comm: mount Not tainted 6.1.55-d23900f.ppcnf-fsp2 #1
  Hardware name: ibm,fsp2 476fpe 0x7ff520c0 FSP-2
  NIP:  b7ee2000 LR: 8c008000 CTR: 00000000
  REGS: bffebd83 TRAP: 0400   Not tainted (6.1.55-d23900f.ppcnf-fs p2)
  MSR:  00000030 <IR,DR>  CR: 00001000  XER: 20000000
  GPR00: c00110ac bffebe63 bffebe7e bffebe88 8c008000 00001000 00000d12 b7ee2000
  GPR08: 00000033 00000000 00000000 c139df10 48224824 1016c314 10160000 00000000
  GPR16: 10160000 10160000 00000008 00000000 10160000 00000000 10160000 1017f5b0
  GPR24: 1017fa50 1017f4f0 1017fa50 1017f740 1017f630 00000000 00000000 1017f4f0
  NIP [b7ee2000] 0xb7ee2000
  LR [8c008000] 0x8c008000
  Call Trace:
  Instruction dump:
  XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX
  XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX
  ---[ end trace 0000000000000000 ]---

The problem is in ret_from_syscall where the check for
icache_44x_need_flush is done. When the flush is needed the code jumps
out-of-line to do the flush, and then intends to jump back to continue
the syscall return.

However the branch back to label 1b doesn't return to the correct
location, instead branching back just prior to the return to userspace,
causing bogus register values to be used by the rfi.

The breakage was introduced by commit 6f76a01173cc
("powerpc/syscall: implement system call entry/exit logic in C for PPC32") which
inadvertently removed the "1" label and reused it elsewhere.

Fix it by adding named local labels in the correct locations. Note that
the return label needs to be outside the ifdef so that CONFIG_PPC_47x=n
compiles.

Fixes: 6f76a01173cc ("powerpc/syscall: implement system call entry/exit logic in C for PPC32")
Cc: stable@vger.kernel.org # v5.12+
Reported-by: Eddie James <eajames@linux.ibm.com>
Tested-by: Eddie James <eajames@linux.ibm.com>
Link: https://lore.kernel.org/linuxppc-dev/fdaadc46-7476-9237-e104-1d2168526e72@linux.ibm.com/
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Link: https://msgid.link/20231010114750.847794-1-mpe@ellerman.id.au
powerpc/85xx: Fix math emulation exception 2023-10-10T10:32:40+00:00 Christophe Leroy christophe.leroy@csgroup.eu 2023-09-25T15:55:51+00:00 8e8a12ecbc86700b5e1a3596ce2b3c43dafad336 Booting mpc85xx_defconfig kernel on QEMU leads to: Bad trap at PC: fe9bab0, SR: 2d000, vector=800 awk[82]: unhandled trap (5) at 0 nip fe9bab0 lr fe9e01c code 5 in libc-2.27.so[fe5a000+17a000] awk[82]: code: 3aa00000 3a800010 4bffe03c 9421fff0 7ca62b78 38a00000 93c10008 83c10008 awk[82]: code: 38210010 4bffdec8 9421ffc0 7c0802a6 <fc00048e> d8010008 4815190d 93810030 Trace/breakpoint trap WARNING: no useful console This is because allthough CONFIG_MATH_EMULATION is selected, Exception 800 calls unknown_exception(). Call emulation_assist_interrupt() instead. Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://msgid.link/066caa6d9480365da9b8ed83692d7101e10ac5f8.1695657339.git.christophe.leroy@csgroup.eu 
Booting mpc85xx_defconfig kernel on QEMU leads to:

Bad trap at PC: fe9bab0, SR: 2d000, vector=800
awk[82]: unhandled trap (5) at 0 nip fe9bab0 lr fe9e01c code 5 in libc-2.27.so[fe5a000+17a000]
awk[82]: code: 3aa00000 3a800010 4bffe03c 9421fff0 7ca62b78 38a00000 93c10008 83c10008
awk[82]: code: 38210010 4bffdec8 9421ffc0 7c0802a6 <fc00048e> d8010008 4815190d 93810030
Trace/breakpoint trap
WARNING: no useful console

This is because allthough CONFIG_MATH_EMULATION is selected,
Exception 800 calls unknown_exception().

Call emulation_assist_interrupt() instead.

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/066caa6d9480365da9b8ed83692d7101e10ac5f8.1695657339.git.christophe.leroy@csgroup.eu
powerpc/stacktrace: Fix arch_stack_walk_reliable() 2023-09-22T10:29:27+00:00 Michael Ellerman mpe@ellerman.id.au 2023-09-21T23:24:41+00:00 c5cc3ca707bc916a3f326364751a41f25040aef3 The changes to copy_thread() made in commit eed7c420aac7 ("powerpc: copy_thread differentiate kthreads and user mode threads") inadvertently broke arch_stack_walk_reliable() because it has knowledge of the stack layout. Fix it by changing the condition to match the new logic in copy_thread(). The changes make the comments about the stack layout incorrect, rather than rephrasing them just refer the reader to copy_thread(). Also the comment about the stack backchain is no longer true, since commit edbd0387f324 ("powerpc: copy_thread add a back chain to the switch stack frame"), so remove that as well. Fixes: eed7c420aac7 ("powerpc: copy_thread differentiate kthreads and user mode threads") Reported-by: Joe Lawrence <joe.lawrence@redhat.com> Reviewed-by: Petr Mladek <pmladek@suse.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://msgid.link/20230921232441.1181843-1-mpe@ellerman.id.au 
The changes to copy_thread() made in commit eed7c420aac7 ("powerpc:
copy_thread differentiate kthreads and user mode threads") inadvertently
broke arch_stack_walk_reliable() because it has knowledge of the stack
layout.

Fix it by changing the condition to match the new logic in
copy_thread(). The changes make the comments about the stack layout
incorrect, rather than rephrasing them just refer the reader to
copy_thread().

Also the comment about the stack backchain is no longer true, since
commit edbd0387f324 ("powerpc: copy_thread add a back chain to the
switch stack frame"), so remove that as well.

Fixes: eed7c420aac7 ("powerpc: copy_thread differentiate kthreads and user mode threads")
Reported-by: Joe Lawrence <joe.lawrence@redhat.com>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20230921232441.1181843-1-mpe@ellerman.id.au
powerpc/dexcr: Move HASHCHK trap handler 2023-09-18T02:23:48+00:00 Benjamin Gray bgray@linux.ibm.com 2023-09-15T03:46:04+00:00 c3f4309693758b13fbb34b3741c2e2801ad28769 Syzkaller reported a sleep in atomic context bug relating to the HASHCHK handler logic: BUG: sleeping function called from invalid context at arch/powerpc/kernel/traps.c:1518 in_atomic(): 0, irqs_disabled(): 1, non_block: 0, pid: 25040, name: syz-executor preempt_count: 0, expected: 0 RCU nest depth: 0, expected: 0 no locks held by syz-executor/25040. irq event stamp: 34 hardirqs last enabled at (33): [<c000000000048b38>] prep_irq_for_enabled_exit arch/powerpc/kernel/interrupt.c:56 [inline] hardirqs last enabled at (33): [<c000000000048b38>] interrupt_exit_user_prepare_main+0x148/0x600 arch/powerpc/kernel/interrupt.c:230 hardirqs last disabled at (34): [<c00000000003e6a4>] interrupt_enter_prepare+0x144/0x4f0 arch/powerpc/include/asm/interrupt.h:176 softirqs last enabled at (0): [<c000000000281954>] copy_process+0x16e4/0x4750 kernel/fork.c:2436 softirqs last disabled at (0): [<0000000000000000>] 0x0 CPU: 15 PID: 25040 Comm: syz-executor Not tainted 6.5.0-rc5-00001-g3ccdff6bb06d #3 Hardware name: IBM,9105-22A POWER10 (raw) 0x800200 0xf000006 of:IBM,FW1040.00 (NL1040_021) hv:phyp pSeries Call Trace: [c0000000a8247ce0] [c00000000032b0e4] __might_resched+0x3b4/0x400 kernel/sched/core.c:10189 [c0000000a8247d80] [c0000000008c7dc8] __might_fault+0xa8/0x170 mm/memory.c:5853 [c0000000a8247dc0] [c00000000004160c] do_program_check+0x32c/0xb20 arch/powerpc/kernel/traps.c:1518 [c0000000a8247e50] [c000000000009b2c] program_check_common_virt+0x3bc/0x3c0 To determine if a trap was caused by a HASHCHK instruction, we inspect the user instruction that triggered the trap. However this may sleep if the page needs to be faulted in (get_user_instr() reaches __get_user(), which calls might_fault() and triggers the bug message). Move the HASHCHK handler logic to after we allow IRQs, which is fine because we are only interested in HASHCHK if it's a user space trap. Fixes: 5bcba4e6c13f ("powerpc/dexcr: Handle hashchk exception") Signed-off-by: Benjamin Gray <bgray@linux.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://msgid.link/20230915034604.45393-1-bgray@linux.ibm.com 
Syzkaller reported a sleep in atomic context bug relating to the HASHCHK
handler logic:

  BUG: sleeping function called from invalid context at arch/powerpc/kernel/traps.c:1518
  in_atomic(): 0, irqs_disabled(): 1, non_block: 0, pid: 25040, name: syz-executor
  preempt_count: 0, expected: 0
  RCU nest depth: 0, expected: 0
  no locks held by syz-executor/25040.
  irq event stamp: 34
  hardirqs last  enabled at (33): [<c000000000048b38>] prep_irq_for_enabled_exit arch/powerpc/kernel/interrupt.c:56 [inline]
  hardirqs last  enabled at (33): [<c000000000048b38>] interrupt_exit_user_prepare_main+0x148/0x600 arch/powerpc/kernel/interrupt.c:230
  hardirqs last disabled at (34): [<c00000000003e6a4>] interrupt_enter_prepare+0x144/0x4f0 arch/powerpc/include/asm/interrupt.h:176
  softirqs last  enabled at (0): [<c000000000281954>] copy_process+0x16e4/0x4750 kernel/fork.c:2436
  softirqs last disabled at (0): [<0000000000000000>] 0x0
  CPU: 15 PID: 25040 Comm: syz-executor Not tainted 6.5.0-rc5-00001-g3ccdff6bb06d #3
  Hardware name: IBM,9105-22A POWER10 (raw) 0x800200 0xf000006 of:IBM,FW1040.00 (NL1040_021) hv:phyp pSeries
  Call Trace:
  [c0000000a8247ce0] [c00000000032b0e4] __might_resched+0x3b4/0x400 kernel/sched/core.c:10189
  [c0000000a8247d80] [c0000000008c7dc8] __might_fault+0xa8/0x170 mm/memory.c:5853
  [c0000000a8247dc0] [c00000000004160c] do_program_check+0x32c/0xb20 arch/powerpc/kernel/traps.c:1518
  [c0000000a8247e50] [c000000000009b2c] program_check_common_virt+0x3bc/0x3c0

To determine if a trap was caused by a HASHCHK instruction, we inspect
the user instruction that triggered the trap. However this may sleep
if the page needs to be faulted in (get_user_instr() reaches
__get_user(), which calls might_fault() and triggers the bug message).

Move the HASHCHK handler logic to after we allow IRQs, which is fine
because we are only interested in HASHCHK if it's a user space trap.

Fixes: 5bcba4e6c13f ("powerpc/dexcr: Handle hashchk exception")
Signed-off-by: Benjamin Gray <bgray@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20230915034604.45393-1-bgray@linux.ibm.com
powerpc/watchpoints: Annotate atomic context in more places 2023-09-18T02:23:47+00:00 Benjamin Gray bgray@linux.ibm.com 2023-08-29T06:34:57+00:00 27646b2e02b096a6936b3e3b6ba334ae20763eab It can be easy to miss that the notifier mechanism invokes the callbacks in an atomic context, so add some comments to that effect on the two handlers we register here. Signed-off-by: Benjamin Gray <bgray@linux.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://msgid.link/20230829063457.54157-4-bgray@linux.ibm.com 
It can be easy to miss that the notifier mechanism invokes the callbacks
in an atomic context, so add some comments to that effect on the two
handlers we register here.

Signed-off-by: Benjamin Gray <bgray@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20230829063457.54157-4-bgray@linux.ibm.com
powerpc/watchpoint: Disable pagefaults when getting user instruction 2023-09-18T02:23:47+00:00 Benjamin Gray bgray@linux.ibm.com 2023-08-29T06:34:56+00:00 3241f260eb830d27d09cc604690ec24533fdb433 This is called in an atomic context, so is not allowed to sleep if a user page needs to be faulted in and has nowhere it can be deferred to. The pagefault_disabled() function is documented as preventing user access methods from sleeping. In practice the page will be mapped in nearly always because we are reading the instruction that just triggered the watchpoint trap. Signed-off-by: Benjamin Gray <bgray@linux.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://msgid.link/20230829063457.54157-3-bgray@linux.ibm.com 
This is called in an atomic context, so is not allowed to sleep if a
user page needs to be faulted in and has nowhere it can be deferred to.
The pagefault_disabled() function is documented as preventing user
access methods from sleeping.

In practice the page will be mapped in nearly always because we are
reading the instruction that just triggered the watchpoint trap.

Signed-off-by: Benjamin Gray <bgray@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20230829063457.54157-3-bgray@linux.ibm.com
powerpc/watchpoints: Disable preemption in thread_change_pc() 2023-09-18T02:23:47+00:00 Benjamin Gray bgray@linux.ibm.com 2023-08-29T06:34:55+00:00 cc879ab3ce39bc39f9b1d238b283f43a5f6f957d thread_change_pc() uses CPU local data, so must be protected from swapping CPUs while it is reading the breakpoint struct. The error is more noticeable after 1e60f3564bad ("powerpc/watchpoints: Track perf single step directly on the breakpoint"), which added an unconditional __this_cpu_read() call in thread_change_pc(). However the existing __this_cpu_read() that runs if a breakpoint does need to be re-inserted has the same issue. Signed-off-by: Benjamin Gray <bgray@linux.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://msgid.link/20230829063457.54157-2-bgray@linux.ibm.com 
thread_change_pc() uses CPU local data, so must be protected from
swapping CPUs while it is reading the breakpoint struct.

The error is more noticeable after 1e60f3564bad ("powerpc/watchpoints:
Track perf single step directly on the breakpoint"), which added an
unconditional __this_cpu_read() call in thread_change_pc(). However the
existing __this_cpu_read() that runs if a breakpoint does need to be
re-inserted has the same issue.

Signed-off-by: Benjamin Gray <bgray@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20230829063457.54157-2-bgray@linux.ibm.com
Merge tag 'powerpc-6.6-1' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux 2023-08-31T19:43:10+00:00 Linus Torvalds torvalds@linux-foundation.org 2023-08-31T19:43:10+00:00 4ad0a4c2343d3981e92df2b39fa262be62a9091a Pull powerpc updates from Michael Ellerman: - Add HOTPLUG_SMT support (/sys/devices/system/cpu/smt) and honour the configured SMT state when hotplugging CPUs into the system - Combine final TLB flush and lazy TLB mm shootdown IPIs when using the Radix MMU to avoid a broadcast TLBIE flush on exit - Drop the exclusion between ptrace/perf watchpoints, and drop the now unused associated arch hooks - Add support for the "nohlt" command line option to disable CPU idle - Add support for -fpatchable-function-entry for ftrace, with GCC >= 13.1 - Rework memory block size determination, and support 256MB size on systems with GPUs that have hotpluggable memory - Various other small features and fixes Thanks to Andrew Donnellan, Aneesh Kumar K.V, Arnd Bergmann, Athira Rajeev, Benjamin Gray, Christophe Leroy, Frederic Barrat, Gautam Menghani, Geoff Levand, Hari Bathini, Immad Mir, Jialin Zhang, Joel Stanley, Jordan Niethe, Justin Stitt, Kajol Jain, Kees Cook, Krzysztof Kozlowski, Laurent Dufour, Liang He, Linus Walleij, Mahesh Salgaonkar, Masahiro Yamada, Michal Suchanek, Nageswara R Sastry, Nathan Chancellor, Nathan Lynch, Naveen N Rao, Nicholas Piggin, Nick Desaulniers, Omar Sandoval, Randy Dunlap, Reza Arbab, Rob Herring, Russell Currey, Sourabh Jain, Thomas Gleixner, Trevor Woerner, Uwe Kleine-König, Vaibhav Jain, Xiongfeng Wang, Yuan Tan, Zhang Rui, and Zheng Zengkai. * tag 'powerpc-6.6-1' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux: (135 commits) macintosh/ams: linux/platform_device.h is needed powerpc/xmon: Reapply "Relax frame size for clang" powerpc/mm/book3s64: Use 256M as the upper limit with coherent device memory attached powerpc/mm/book3s64: Fix build error with SPARSEMEM disabled powerpc/iommu: Fix notifiers being shared by PCI and VIO buses powerpc/mpc5xxx: Add missing fwnode_handle_put() powerpc/config: Disable SLAB_DEBUG_ON in skiroot powerpc/pseries: Remove unused hcall tracing instruction powerpc/pseries: Fix hcall tracepoints with JUMP_LABEL=n powerpc: dts: add missing space before { powerpc/eeh: Use pci_dev_id() to simplify the code powerpc/64s: Move CPU -mtune options into Kconfig powerpc/powermac: Fix unused function warning powerpc/pseries: Rework lppaca_shared_proc() to avoid DEBUG_PREEMPT powerpc: Don't include lppaca.h in paca.h powerpc/pseries: Move hcall_vphn() prototype into vphn.h powerpc/pseries: Move VPHN constants into vphn.h cxl: Drop unused detach_spa() powerpc: Drop zalloc_maybe_bootmem() powerpc/powernv: Use struct opal_prd_msg in more places ... 
Pull powerpc updates from Michael Ellerman:

 - Add HOTPLUG_SMT support (/sys/devices/system/cpu/smt) and honour the
   configured SMT state when hotplugging CPUs into the system

 - Combine final TLB flush and lazy TLB mm shootdown IPIs when using the
   Radix MMU to avoid a broadcast TLBIE flush on exit

 - Drop the exclusion between ptrace/perf watchpoints, and drop the now
   unused associated arch hooks

 - Add support for the "nohlt" command line option to disable CPU idle

 - Add support for -fpatchable-function-entry for ftrace, with GCC >=
   13.1

 - Rework memory block size determination, and support 256MB size on
   systems with GPUs that have hotpluggable memory

 - Various other small features and fixes

Thanks to Andrew Donnellan, Aneesh Kumar K.V, Arnd Bergmann, Athira
Rajeev, Benjamin Gray, Christophe Leroy, Frederic Barrat, Gautam
Menghani, Geoff Levand, Hari Bathini, Immad Mir, Jialin Zhang, Joel
Stanley, Jordan Niethe, Justin Stitt, Kajol Jain, Kees Cook, Krzysztof
Kozlowski, Laurent Dufour, Liang He, Linus Walleij, Mahesh Salgaonkar,
Masahiro Yamada, Michal Suchanek, Nageswara R Sastry, Nathan Chancellor,
Nathan Lynch, Naveen N Rao, Nicholas Piggin, Nick Desaulniers, Omar
Sandoval, Randy Dunlap, Reza Arbab, Rob Herring, Russell Currey, Sourabh
Jain, Thomas Gleixner, Trevor Woerner, Uwe Kleine-König, Vaibhav Jain,
Xiongfeng Wang, Yuan Tan, Zhang Rui, and Zheng Zengkai.

* tag 'powerpc-6.6-1' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux: (135 commits)
  macintosh/ams: linux/platform_device.h is needed
  powerpc/xmon: Reapply "Relax frame size for clang"
  powerpc/mm/book3s64: Use 256M as the upper limit with coherent device memory attached
  powerpc/mm/book3s64: Fix build error with SPARSEMEM disabled
  powerpc/iommu: Fix notifiers being shared by PCI and VIO buses
  powerpc/mpc5xxx: Add missing fwnode_handle_put()
  powerpc/config: Disable SLAB_DEBUG_ON in skiroot
  powerpc/pseries: Remove unused hcall tracing instruction
  powerpc/pseries: Fix hcall tracepoints with JUMP_LABEL=n
  powerpc: dts: add missing space before {
  powerpc/eeh: Use pci_dev_id() to simplify the code
  powerpc/64s: Move CPU -mtune options into Kconfig
  powerpc/powermac: Fix unused function warning
  powerpc/pseries: Rework lppaca_shared_proc() to avoid DEBUG_PREEMPT
  powerpc: Don't include lppaca.h in paca.h
  powerpc/pseries: Move hcall_vphn() prototype into vphn.h
  powerpc/pseries: Move VPHN constants into vphn.h
  cxl: Drop unused detach_spa()
  powerpc: Drop zalloc_maybe_bootmem()
  powerpc/powernv: Use struct opal_prd_msg in more places
  ...
Merge tag 'integrity-v6.6' of git://git.kernel.org/pub/scm/linux/kernel/git/zohar/linux-integrity 2023-08-30T16:16:56+00:00 Linus Torvalds torvalds@linux-foundation.org 2023-08-30T16:16:56+00:00 1a35914f738c564060a14388f52a06669b09e0b3 Pull integrity subsystem updates from Mimi Zohar: - With commit 099f26f22f58 ("integrity: machine keyring CA configuration") certificates may be loaded onto the IMA keyring, directly or indirectly signed by keys on either the "builtin" or the "machine" keyrings. With the ability for the system/machine owner to sign the IMA policy itself without needing to recompile the kernel, update the IMA architecture specific policy rules to require the IMA policy itself be signed. [ As commit 099f26f22f58 was upstreamed in linux-6.4, updating the IMA architecture specific policy now to require signed IMA policies may break userspace expectations. ] - IMA only checked the file data hash was not on the system blacklist keyring for files with an appended signature (e.g. kernel modules, Power kernel image). Check all file data hashes regardless of how it was signed - Code cleanup, and a kernel-doc update * tag 'integrity-v6.6' of git://git.kernel.org/pub/scm/linux/kernel/git/zohar/linux-integrity: kexec_lock: Replace kexec_mutex() by kexec_lock() in two comments ima: require signed IMA policy when UEFI secure boot is enabled integrity: Always reference the blacklist keyring with appraisal ima: Remove deprecated IMA_TRUSTED_KEYRING Kconfig 
Pull integrity subsystem updates from Mimi Zohar:

 - With commit 099f26f22f58 ("integrity: machine keyring CA
   configuration") certificates may be loaded onto the IMA keyring,
   directly or indirectly signed by keys on either the "builtin" or the
   "machine" keyrings.

   With the ability for the system/machine owner to sign the IMA policy
   itself without needing to recompile the kernel, update the IMA
   architecture specific policy rules to require the IMA policy itself
   be signed.

   [ As commit 099f26f22f58 was upstreamed in linux-6.4, updating the
     IMA architecture specific policy now to require signed IMA policies
     may break userspace expectations. ]

 - IMA only checked the file data hash was not on the system blacklist
   keyring for files with an appended signature (e.g. kernel modules,
   Power kernel image).

   Check all file data hashes regardless of how it was signed

 - Code cleanup, and a kernel-doc update

* tag 'integrity-v6.6' of git://git.kernel.org/pub/scm/linux/kernel/git/zohar/linux-integrity:
  kexec_lock: Replace kexec_mutex() by kexec_lock() in two comments
  ima: require signed IMA policy when UEFI secure boot is enabled
  integrity: Always reference the blacklist keyring with appraisal
  ima: Remove deprecated IMA_TRUSTED_KEYRING Kconfig