kernel/linux.git/arch/mips/include/asm/dec, branch v7.2-rc1

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

2026-05-26T14:35:36+00:00

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

MIPS: DEC: Fix prototypes for halt/reset handlers

2026-05-26T14:35:36+00:00

Remove a bunch of compilation warnings for halt/reset handlers: arch/mips/dec/reset.c:22:17: warning: no previous prototype for 'dec_machine_restart' [-Wmissing-prototypes] 22 | void __noreturn dec_machine_restart(char *command) | ^~~~~~~~~~~~~~~~~~~ arch/mips/dec/reset.c:27:17: warning: no previous prototype for 'dec_machine_halt' [-Wmissing-prototypes] 27 | void __noreturn dec_machine_halt(void) | ^~~~~~~~~~~~~~~~ arch/mips/dec/reset.c:32:17: warning: no previous prototype for 'dec_machine_power_off' [-Wmissing-prototypes] 32 | void __noreturn dec_machine_power_off(void) | ^~~~~~~~~~~~~~~~~~~~~ arch/mips/dec/reset.c:38:13: warning: no previous prototype for 'dec_intr_halt' [-Wmissing-prototypes] 38 | irqreturn_t dec_intr_halt(int irq, void *dev_id) | ^~~~~~~~~~~~~ (which get promoted to compilation errors with CONFIG_WERROR), by moving the local prototypes from arch/mips/dec/setup.c to a dedicated header for arch/mips/dec/reset.c to use as well. No functional change. Signed-off-by: Maciej W. Rozycki Signed-off-by: Thomas Bogendoerfer

mips: Replace ASSEMBLY with ASSEMBLER in the mips headers

2025-08-29T20:34:29+00:00

While the GCC and Clang compilers already define __ASSEMBLER__ automatically when compiling assembler code, __ASSEMBLY__ is a macro that only gets defined by the Makefiles in the kernel. Defining such a macro was necessary in the early days of the kernel, since GCC only started providing __ASSEMBLER__ since version 3.0 in 2000 (see https://gcc.gnu.org/git/?p=gcc.git;a=commitdiff;h=f8f769ea4e69 ). However, having two macros can be very confusing nowadays for the developers when switching between userspace and kernelspace coding, or when dealing with uapi headers that should use __ASSEMBLER__ instead. So let's now standardize on the __ASSEMBLER__ macro that is provided by the compilers. This is almost a completely mechanical patch (done with a simple "sed -i" statement), with just one comment tweaked manually in arch/mips/include/asm/cpu.h (that was missing some underscores). Cc: Thomas Bogendoerfer Cc: linux-mips@vger.kernel.org Reviewed-by: Philippe Mathieu-Daudé Reviewed-by: Maciej W. Rozycki Signed-off-by: Thomas Huth Signed-off-by: Thomas Bogendoerfer

MIPS: dec: prom: Remove unused unregister_prom_console() declaration

2024-08-29T08:44:08+00:00

The unregister_prom_console() has been removed since commit 36a885306fdf ("[MIPS] Fix and cleanup the mess that a dozen prom_printf variants are."), so remove it. Signed-off-by: Gaosheng Cui Acked-by: Maciej W. Rozycki Signed-off-by: Thomas Bogendoerfer

MIPS: dec: prom: Address -Warray-bounds warning

2023-06-23T13:00:29+00:00

Zero-length arrays are deprecated, and we are replacing them with flexible array members instead. So, replace zero-length array with flexible-array member in struct memmap. Address the following warning found after building (with GCC-13) mips64 with decstation_64_defconfig: In function 'rex_setup_memory_region', inlined from 'prom_meminit' at arch/mips/dec/prom/memory.c:91:3: arch/mips/dec/prom/memory.c:72:31: error: array subscript i is outside array bounds of 'unsigned char[0]' [-Werror=array-bounds=] 72 | if (bm->bitmap[i] == 0xff) | ~~~~~~~~~~^~~ In file included from arch/mips/dec/prom/memory.c:16: ./arch/mips/include/asm/dec/prom.h: In function 'prom_meminit': ./arch/mips/include/asm/dec/prom.h:73:23: note: while referencing 'bitmap' 73 | unsigned char bitmap[0]; This helps with the ongoing efforts to globally enable -Warray-bounds. This results in no differences in binary output. Link: https://github.com/KSPP/linux/issues/79 Link: https://github.com/KSPP/linux/issues/323 Signed-off-by: Gustavo A. R. Silva Signed-off-by: Thomas Bogendoerfer

DEC: Limit PMAX memory probing to R3k systems

2022-03-07T12:10:44+00:00

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

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152

2019-05-30T18:26:32+00:00

Based on 1 normalized pattern(s): this program is free software you can redistribute it and or modify it under the terms of the gnu general public license as published by the free software foundation either version 2 of the license or at your option any later version extracted by the scancode license scanner the SPDX license identifier GPL-2.0-or-later has been chosen to replace the boilerplate/reference in 3029 file(s). Signed-off-by: Thomas Gleixner Reviewed-by: Allison Randal Cc: linux-spdx@vger.kernel.org Link: https://lkml.kernel.org/r/20190527070032.746973796@linutronix.de Signed-off-by: Greg Kroah-Hartman

DEC: Document the R4k MB ASIC mini interrupt controller

2014-06-04T20:50:41+00:00

There's an alternative 5-line mini interrupt controller in the R4k MB ASIC used on the KN04 and KN05 CPU daughtercards. The controller is cascaded from the CPU interrupt input that would be used for the Halt button on the corresponding R3k systems. This change documents the findings so far. Signed-off-by: Maciej W. Rozycki Cc: linux-mips@linux-mips.org Patchwork: http://patchwork.linux-mips.org/patch/6706/ Signed-off-by: Ralf Baechle

MIPS: DEC/SNI: O32 wrapper stack switching fixes

2014-05-12T22:29:35+00:00

Commit 231a35d37293ab88d325a9cb94e5474c156282c0 [[MIPS] RM: Collected changes] broke DECstation support by introducing an incompatible copy of arch/mips/dec/prom/call_o32.S in arch/mips/fw/lib/, built unconditionally. The copy happens to land earlier of the two among the modules used in the link and is therefore chosen for the DECstation rather than the intended original. As a result random kernel data is corrupted because a pointer to the "%s" formatted output template is used as a temporary stack pointer rather than being passed down to prom_printf. This also explains why prom_printf still works, up to a point -- the next argument is the actual string to output so it works just fine as the output template until enough kernel data has been corrupted to cause a crash. This change adjusts the modified wrapper in arch/mips/fw/lib/call_o32.S to let callers request no stack switching by passing a null temporary stack pointer in $a1, reworks the DECstation callers to work with the updated interface and removes the old copy from arch/mips/dec/prom/call_o32.S. A few minor readability adjustments are included as well, most importantly O32_SZREG is now used throughout where applicable rather than hardcoded multiplies of 4 and $fp is used to access the argument save area as a more usual register to operate the stack with rather than $s0. Finally an update is made to the temporary stack space used by the SNI platform to guarantee 8-byte alignment as per o32 requirements. Signed-off-by: Maciej W. Rozycki Cc: Thomas Bogendoerfer Cc: linux-mips@linux-mips.org Patchwork: https://patchwork.linux-mips.org/patch/6668/ Signed-off-by: Ralf Baechle

DEC: Whitespace cleanup

2013-10-29T20:24:44+00:00

Commit 7034228792cc561e79ff8600f02884bd4c80e287 [MIPS: Whitespace cleanup.] did a lot of good and a little damage. Revert the damage. Signed-off-by: Maciej W. Rozycki Cc: linux-mips@linux-mips.org Patchwork: https://patchwork.linux-mips.org/patch/5875/ Signed-off-by: Ralf Baechle