kernel/linux.git/arch/mips/dec, branch v5.10.261

MIPS: DEC: Ensure 32-bit stack location for o32 prom_printf()

2026-07-24T13:49:11+00:00

commit 5ff79e8bdc75db51e30298a75939e2308e7658e0 upstream. In 64-bit configurations calling any firmware entry points from a kernel thread other than the initial one will result in a situation where the stack has been placed in the XKPHYS 64-bit memory segment. Consequently the stack pointer is no longer a 32-bit value and when the 32-bit firmware code called uses 32-bit ALU operations to manipulate the stack pointer, the calculated result is incorrect (in fact in the 64-bit MIPS ISA almost all 32-bit ALU operations will produce an unpredictable result when executed on 64-bit data) and control goes astray. This may happen when no final console driver has been enabled in the configuration and consequently the initial console continues being used late into bootstrap, or with an upcoming change that will switch the zs driver to use a platform device, which in turn will make the console handover happen only after other kernel threads have already been started, and the kernel will hang at: pid_max: default: 32768 minimum: 301 or somewhat later, but always before: cblist_init_generic: Setting adjustable number of callback queues. has been printed. It seems that only the prom_printf() entry point is affected. Of all the other entry points wired only rex_slot_address() and rex_gettcinfo() are called from a kernel thread other than the initial one, specifically kernel_init(), and they are leaf functions that do no business with the stack, having worked with no issue ever since 64-bit support was added for the platform back in 2002. To address this issue then, arrange for the stack to be switched in the o32 wrapper as required for prom_printf() only, by supplying call_o32() with a pointer to a chunk of initdata space, which is placed in the CKSEG0 32-bit compatibility segment, observing that prom_printf() is only called from console output handler and therefore with the console lock held, implying no need for this code to be reentrant. Other firmware entry points may be called with interrupts enabled and no lock held, and may therefore require that call_o32() be reentrant. They trigger no issue at this point and "if it ain't broke, don't fix it," so just leave them alone. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Maciej W. Rozycki Cc: stable@vger.kernel.org # v2.6.12+ Signed-off-by: Thomas Bogendoerfer Signed-off-by: Greg Kroah-Hartman

MIPS: DEC: Remove do_IRQ() call indirection

2026-07-24T13:48:57+00:00

[ Upstream commit 35554eadc1b127bb5294504a4ac8f3a5dd9e299d ] As from commit 8f99a1626535 ("MIPS: Tracing: Add IRQENTRY_EXIT section for MIPS") do_IRQ() is not a macro anymore and can be invoked directly from assembly code, as a tail call. Remove the dec_irq_dispatch() stub then and the indirection previously introduced with commit 187933f23679 ("[MIPS] do_IRQ cleanup"), improving performance by reducing the number of control flow changes and the overall instruction count, while fixing a compiler's complaint about a missing prototype for said stub: arch/mips/dec/setup.c:780:25: warning: no previous prototype for 'dec_irq_dispatch' [-Wmissing-prototypes] 780 | asmlinkage unsigned int dec_irq_dispatch(unsigned int irq) | ^~~~~~~~~~~~~~~~ (which gets promoted to a compilation error with CONFIG_WERROR). Fixes: 8f99a1626535 ("MIPS: Tracing: Add IRQENTRY_EXIT section for MIPS") Signed-off-by: Maciej W. Rozycki Signed-off-by: Thomas Bogendoerfer Signed-off-by: Sasha Levin

MIPS: DEC: Prevent initial console buffer from landing in XKPHYS

2026-07-04T11:38:40+00:00

commit 7fb13fd35110ebe95eb053faf79d018f51144d85 upstream. In 64-bit configurations calling the initial console output handler from a kernel thread other than the initial one will result in a situation where the stack has been placed in the XKPHYS 64-bit memory segment and consequently so has been the buffer allocated there that is used as the argument corresponding to the `%s' output conversion specifier for the firmware's printf() entry point. This 64-bit address will then be truncated by 32-bit firmware, resulting in an attempt to access the wrong memory location, which in turn will cause all kinds of unpredictable behaviour, such as a kernel crash: Console: colour dummy device 160x64 Calibrating delay loop... 49.36 BogoMIPS (lpj=192512) pid_max: default: 32768 minimum: 301 CPU 0 Unable to handle kernel paging request at virtual address 000000000203bd00, epc == ffffffffbfc08364, ra == ffffffffbfc08800 Oops[#1]: CPU: 0 PID: 0 Comm: swapper Not tainted 5.18.0-rc2-00254-gfb649bda6f56-dirty #121 $ 0 : 0000000000000000 0000000000000001 0000000000000023 ffffffff80684ba0 $ 4 : 000000000203bd00 ffffffffbfc0f3b4 ffffffffffffffff 0000000000000073 $ 8 : 0a303d7469000000 0000000000000000 0000000000000073 ffffffffbfc0f473 $12 : 0000000000000002 0000000000000000 ffffffff80684c1c 0000000000000000 $16 : 0000000000000000 ffffffff80596dc9 0000000000000000 ffffffffbfc09240 $20 : ffffffff80684c40 ffffffffbfc0f400 000000000000002d 000000000000002b $24 : ffffffffffffffbf 000000000203bd00 $28 : ffffffff805f0000 ffffffff80684b58 0000000000000030 ffffffffbfc08800 Hi : 0000000000000000 Lo : 0000000000000aa8 epc : ffffffffbfc08364 0xffffffffbfc08364 ra : ffffffffbfc08800 0xffffffffbfc08800 Status: 140120e2 KX SX UX KERNEL EXL Cause : 00000008 (ExcCode 02) BadVA : 000000000203bd00 PrId : 00000430 (R4000SC) Modules linked in: Process swapper (pid: 0, threadinfo=(____ptrval____), task=(____ptrval____), tls=0000000000000000) Stack : 0000000000000000 0000000000000000 0000000000000000 0000004d0000004d 80684cc0806a2a40 80596dc80000004d 8061000000000000 bfc0850c80684c38 0000000000000000 000000000203bd00 0000000000000000 0000000000000000 0000000000000000 00000000bfc0f3b4 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000002500000000 0000000000000000 0000000000000000 802c1a7400000000 0203bd0080596dc8 0203bd4d69000000 6c61632000000018 5f746567646e6172 6c616320625f6d6f 5f736e5f6d6f7266 206361323778302b 303d74696e726320 806a0a38806b0000 806a0a38806b0000 00000000806b0000 80683c58806b0000 ... Call Trace: Code: a082ffff 03e00008 00601021 <80820000> 00001821 10400005 24840001 80820000 24630001 ---[ end trace 0000000000000000 ]--- Kernel panic - not syncing: Fatal exception in interrupt KN04 V2.1k (PC: 0xa0026768, SP: 0x806848e8) >> In this case the pointer in $4 was truncated from 0x980000000203bd00 to 0x000000000203bd00. This may happen when no final console driver has been enabled in the configuration and consequently the initial console continues being used late into bootstrap or with an upcoming change that will switch the zs driver to use a platform device, which in turn will make the console handover happen only after other kernel threads have already been started. Fix the issue by making the buffer static and initdata, and therefore placed in the CKSEG0 32-bit compatibility segment, observing that the console output handler is called with the console lock held, implying no need for this code to be reentrant. Add an assertion to verify the buffer actually has been placed in a compatibility segment. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Maciej W. Rozycki Cc: stable@vger.kernel.org # v2.6.12+ Signed-off-by: Thomas Bogendoerfer Signed-off-by: Greg Kroah-Hartman

MIPS: dec: Declare which_prom() as static

2025-05-02T05:41:08+00:00

commit 55fa5868519bc48a7344a4c070efa2f4468f2167 upstream. Declare which_prom() as static to suppress gcc compiler warning that 'missing-prototypes'. This function is not intended to be called from other parts. Fix follow error with gcc-14 when -Werror: arch/mips/dec/prom/init.c:45:13: error: no previous prototype for ‘which_prom’ [-Werror=missing-prototypes] 45 | void __init which_prom(s32 magic, s32 *prom_vec) | ^~~~~~~~~~ cc1: all warnings being treated as errors make[6]: *** [scripts/Makefile.build:207: arch/mips/dec/prom/init.o] Error 1 make[5]: *** [scripts/Makefile.build:465: arch/mips/dec/prom] Error 2 make[5]: *** Waiting for unfinished jobs.... Signed-off-by: WangYuli Signed-off-by: Thomas Bogendoerfer Signed-off-by: Greg Kroah-Hartman

mips: DEC: honor CONFIG_MIPS_FP_SUPPORT=n

2022-04-08T12:40:20+00:00

[ Upstream commit 97bf0395c226907e1a9b908511a35192bf1e09bb ] Include the DECstation interrupt handler in opting out of FPU support. Fixes a linker error: mips-linux-ld: arch/mips/dec/int-handler.o: in function `fpu': (.text+0x148): undefined reference to `handle_fpe_int' Fixes: 183b40f992c8 ("MIPS: Allow FP support to be disabled") Signed-off-by: Randy Dunlap Reported-by: kernel test robot Cc: Paul Burton Cc: Thomas Bogendoerfer Cc: Maciej W. Rozycki Cc: linux-mips@vger.kernel.org Acked-by: Maciej W. Rozycki Signed-off-by: Thomas Bogendoerfer Signed-off-by: Sasha Levin

DEC: Limit PMAX memory probing to R3k systems

2022-04-08T12:39:57+00:00

commit 244eae91a94c6dab82b3232967d10eeb9dfa21c6 upstream. Recent tightening of the opcode table in binutils so as to consistently disallow the assembly or disassembly of CP0 instructions not supported by the processor architecture chosen has caused a regression like below: arch/mips/dec/prom/locore.S: Assembler messages: arch/mips/dec/prom/locore.S:29: Error: opcode not supported on this processor: r4600 (mips3) `rfe' in a piece of code used to probe for memory with PMAX DECstation models, which have non-REX firmware. Those computers always have an R2000 CPU and consequently the exception handler used in memory probing uses the RFE instruction, which those processors use. While adding 64-bit support this code was correctly excluded for 64-bit configurations, however it should have also been excluded for irrelevant 32-bit configurations. Do this now then, and only enable PMAX memory probing for R3k systems. Reported-by: Jan-Benedict Glaw Reported-by: Sudip Mukherjee Signed-off-by: Maciej W. Rozycki Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Cc: stable@vger.kernel.org # v2.6.12+ Signed-off-by: Thomas Bogendoerfer Signed-off-by: Greg Kroah-Hartman

MIPS: DEC: Restore bootmem reservation for firmware working memory area

2020-10-14T21:57:57+00:00

Fix a crash on DEC platforms starting with: VFS: Mounted root (nfs filesystem) on device 0:11. Freeing unused PROM memory: 124k freed BUG: Bad page state in process swapper pfn:00001 page:(ptrval) refcount:0 mapcount:-128 mapping:00000000 index:0x1 pfn:0x1 flags: 0x0() raw: 00000000 00000100 00000122 00000000 00000001 00000000 ffffff7f 00000000 page dumped because: nonzero mapcount Modules linked in: CPU: 0 PID: 1 Comm: swapper Not tainted 5.9.0-00858-g865c50e1d279 #1 Stack : 8065dc48 0000000b 8065d2b8 9bc27dcc 80645bfc 9bc259a4 806a1b97 80703124 80710000 8064a900 00000001 80099574 806b116c 1000ec00 9bc27d88 806a6f30 00000000 00000000 80645bfc 00000000 31232039 80706ba4 2e392e35 8039f348 2d383538 00000070 0000000a 35363867 00000000 806c2830 80710000 806b0000 80710000 8064a900 00000001 81000000 00000000 00000000 8035af2c 80700000 ... Call Trace: [<8004bc5c>] show_stack+0x34/0x104 [<8015675c>] bad_page+0xfc/0x128 [<80157714>] free_pcppages_bulk+0x1f4/0x5dc [<801591cc>] free_unref_page+0xc0/0x130 [<8015cb04>] free_reserved_area+0x144/0x1d8 [<805abd78>] kernel_init+0x20/0x100 [<80046070>] ret_from_kernel_thread+0x14/0x1c Disabling lock debugging due to kernel taint caused by an attempt to free bootmem space that as from commit b93ddc4f9156 ("mips: Reserve memory for the kernel image resources") has not been anymore reserved due to the removal of generic MIPS arch code that used to reserve all the memory from the beginning of RAM up to the kernel load address. This memory does need to be reserved on DEC platforms however as it is used by REX firmware as working area, as per the TURBOchannel firmware specification[1]: Table 2-2 REX Memory Regions ------------------------------------------------------------------------- Starting Ending Region Address Address Use ------------------------------------------------------------------------- 0 0xa0000000 0xa000ffff Restart block, exception vectors, REX stack and bss 1 0xa0010000 0xa0017fff Keyboard or tty drivers 2 0xa0018000 0xa001f3ff 1) CRT driver 3 0xa0020000 0xa002ffff boot, cnfg, init and t objects 4 0xa0020000 0xa002ffff 64KB scratch space ------------------------------------------------------------------------- 1) Note that the last 3 Kbytes of region 2 are reserved for backward compatibility with previous system software. ------------------------------------------------------------------------- (this table uses KSEG2 unmapped virtual addresses, which in the MIPS architecture are offset from physical addresses by a fixed value of 0xa0000000 and therefore the regions referred do correspond to the beginning of the physical address space) and we call into the firmware on several occasions throughout the bootstrap process. It is believed that pre-REX firmware used with non-TURBOchannel DEC platforms has the same requirements, as hinted by note #1 cited. Recreate the discarded reservation then, in DEC platform code, removing the crash. References: [1] "TURBOchannel Firmware Specification", On-line version, EK-TCAAD-FS-004, Digital Equipment Corporation, January 1993, Chapter 2 "System Module Firmware", p. 2-5 Signed-off-by: Maciej W. Rozycki Fixes: b93ddc4f9156 ("mips: Reserve memory for the kernel image resources") Cc: stable@vger.kernel.org # v5.2+ Signed-off-by: Thomas Bogendoerfer

MIPS: dec: fix section mismatch

2020-10-14T21:54:28+00:00

Drop inline for memory setup functions and mark them __init to fix section mismatch of pmax_setup_memory_region. Signed-off-by: Thomas Bogendoerfer Acked-by: Maciej W. Rozycki

MIPS: replace add_memory_region with memblock

2020-10-12T10:01:36+00:00

add_memory_region was the old interface for registering memory and was already changed to used memblock internaly. Replace it by directly calling memblock functions. Signed-off-by: Thomas Bogendoerfer

MIPS: Only include the platform file needed

2020-05-12T22:17:18+00:00

Instead of including all Platform files, we simply include the needed one and avoid clashes with makefile variables. Signed-off-by: Thomas Bogendoerfer