kernel/arch/arc, branch linux-5.10.y

arc: Fix fls() const-foldability via builtin_clzl()

2025-12-06T21:08:09Z

[ Upstream commit a3fecb9160482367365cc384c59dd220b162b066 ] While tracking down a problem where constant expressions used by BUILD_BUG_ON() suddenly stopped working[1], we found that an added static initializer was convincing the compiler that it couldn't track the state of the prior statically initialized value. Tracing this down found that ffs() was used in the initializer macro, but since it wasn't marked with __attribute__const__, the compiler had to assume the function might change variable states as a side-effect (which is not true for ffs(), which provides deterministic math results). For arc architecture with CONFIG_ISA_ARCV2=y, the __fls() function uses __builtin_arc_fls() which lacks GCC's const attribute, preventing compile-time constant folding, and KUnit testing of ffs/fls fails on arc[3]. A patch[2] to GCC to solve this has been sent. Add a fix for this by handling compile-time constants with the standard __builtin_clzl() builtin (which has const attribute) while preserving the optimized arc-specific builtin for runtime cases. This has the added benefit of skipping runtime calculation of compile-time constant values. Even with the GCC bug fixed (which is about "attribute const") this is a good change to avoid needless runtime costs, and should be done regardless of the state of GCC's bug. Build tested ARCH=arc allyesconfig with GCC arc-linux 15.2.0. Link: https://github.com/KSPP/linux/issues/364 [1] Link: https://gcc.gnu.org/pipermail/gcc-patches/2025-August/693273.html Reported-by: kernel test robot Closes: https://lore.kernel.org/oe-kbuild-all/202508031025.doWxtzzc-lkp@intel.com/ [3] Signed-off-by: Kees Cook Acked-by: Vineet Gupta Signed-off-by: Yury Norov (NVIDIA) Signed-off-by: Sasha Levin

ARC: build: Try to guess GCC variant of cross compiler

2025-01-09T12:25:05Z

[ Upstream commit 824927e88456331c7a999fdf5d9d27923b619590 ] ARC GCC compiler is packaged starting from Fedora 39i and the GCC variant of cross compile tools has arc-linux-gnu- prefix and not arc-linux-. This is causing that CROSS_COMPILE variable is left unset. This change allows builds without need to supply CROSS_COMPILE argument if distro package is used. Before this change: $ make -j 128 ARCH=arc W=1 drivers/infiniband/hw/mlx4/ gcc: warning: ‘-mcpu=’ is deprecated; use ‘-mtune=’ or ‘-march=’ instead gcc: error: unrecognized command-line option ‘-mmedium-calls’ gcc: error: unrecognized command-line option ‘-mlock’ gcc: error: unrecognized command-line option ‘-munaligned-access’ [1] https://packages.fedoraproject.org/pkgs/cross-gcc/gcc-arc-linux-gnu/index.html Signed-off-by: Leon Romanovsky Signed-off-by: Vineet Gupta Signed-off-by: Sasha Levin

ARC: [plat-hsdk]: Remove misplaced interrupt-cells property

2024-05-02T14:23:41Z

[ Upstream commit 61231eb8113ce47991f35024f9c20810b37996bf ] "gmac" node stands for just an ordinary Ethernet controller, which is by no means a provider of interrupts, i.e. it doesn't serve as an interrupt controller, thus "#interrupt-cells" property doesn't belong to it and so we remove it. Fixes: ------------>8------------ DTC arch/arc/boot/dts/hsdk.dtb arch/arc/boot/dts/hsdk.dts:207.23-235.5: Warning (interrupt_provider): /soc/ethernet@8000: '#interrupt-cells' found, but node is not an interrupt provider arch/arc/boot/dts/hsdk.dtb: Warning (interrupt_map): Failed prerequisite 'interrupt_provider' ------------>8------------ Reported-by: Vineet Gupta Signed-off-by: Alexey Brodkin Signed-off-by: Vineet Gupta Signed-off-by: Sasha Levin

ARC: fix spare error

2024-01-25T22:37:38Z

[ Upstream commit aca02d933f63ba8bc84258bf35f9ffaf6b664336 ] Reported-by: kernel test robot Closes: https://lore.kernel.org/oe-kbuild-all/202312082320.VDN5A9hb-lkp@intel.com/ Signed-off-by: Vineet Gupta Signed-off-by: Sasha Levin

ARC: define ASM_NL and __ALIGN(_STR) outside #ifdef ASSEMBLY guard

2023-07-27T06:44:00Z

[ Upstream commit 92e2921eeafdfca9acd9b83f07d2b7ca099bac24 ] ASM_NL is useful not only in *.S files but also in .c files for using inline assembler in C code. On ARC, however, ASM_NL is evaluated inconsistently. It is expanded to a backquote (`) in *.S files, but a semicolon (;) in *.c files because arch/arc/include/asm/linkage.h defines it inside #ifdef __ASSEMBLY__, so the definition for C code falls back to the default value defined in include/linux/linkage.h. If ASM_NL is used in inline assembler in .c files, it will result in wrong assembly code because a semicolon is not an instruction separator, but the start of a comment for ARC. Move ASM_NL (also __ALIGN and __ALIGN_STR) out of the #ifdef. Fixes: 9df62f054406 ("arch: use ASM_NL instead of ';' for assembler new line character in the macro") Fixes: 8d92e992a785 ("ARC: define __ALIGN_STR and __ALIGN symbols for ARC") Signed-off-by: Masahiro Yamada Signed-off-by: Sasha Levin

arch: setup PF_IO_WORKER threads like PF_KTHREAD

2023-01-04T10:39:22Z

[ Upstream commit 4727dc20e0422211a0e0c72b1ace4ed6096df8a6 ] PF_IO_WORKER are kernel threads too, but they aren't PF_KTHREAD in the sense that we don't assign ->set_child_tid with our own structure. Just ensure that every arch sets up the PF_IO_WORKER threads like kthreads in the arch implementation of copy_thread(). Signed-off-by: Jens Axboe Signed-off-by: Greg Kroah-Hartman

ARC: unbork 5.11 bootup: fix snafu in _TIF_NOTIFY_SIGNAL handling

2023-01-04T10:39:21Z

[ Upstream commit bb12433bf56e76789c6b08b36c546f745a6aa6e1 ] Linux 5.11.rcX was failing to boot on ARC HSDK board. Turns out we have a couple of issues, this being the first one, and I'm to blame as I didn't pay attention during review. TIF_NOTIFY_SIGNAL support requires checking multiple TIF_* bits in kernel return code path. Old code only needed to check a single bit so BBIT0 worked. New code needs to check multiple bits so AND instruction. So needs to use bit mask variant _TIF_SIGPENDING Cc: Jens Axboe Fixes: 53855e12588743ea128 ("arc: add support for TIF_NOTIFY_SIGNAL") Link: https://github.com/foss-for-synopsys-dwc-arc-processors/linux/issues/34 Signed-off-by: Vineet Gupta Signed-off-by: Greg Kroah-Hartman

arc: add support for TIF_NOTIFY_SIGNAL

2023-01-04T10:39:18Z

[ Upstream commit 53855e12588743ea128ee31f913d1c6e2f1d32c8 ] Wire up TIF_NOTIFY_SIGNAL handling for arc. Cc: linux-snps-arc@lists.infradead.org Acked-by: Vineet Gupta Signed-off-by: Jens Axboe Signed-off-by: Greg Kroah-Hartman

arc: iounmap() arg is volatile

2022-11-03T14:57:51Z

[ Upstream commit c44f15c1c09481d50fd33478ebb5b8284f8f5edb ] Add 'volatile' to iounmap()'s argument to prevent build warnings. This make it the same as other major architectures. Placates these warnings: (12 such warnings) ../drivers/video/fbdev/riva/fbdev.c: In function 'rivafb_probe': ../drivers/video/fbdev/riva/fbdev.c:2067:42: error: passing argument 1 of 'iounmap' discards 'volatile' qualifier from pointer target type [-Werror=discarded-qualifiers] 2067 | iounmap(default_par->riva.PRAMIN); Fixes: 1162b0701b14b ("ARC: I/O and DMA Mappings") Signed-off-by: Randy Dunlap Cc: Vineet Gupta Cc: linux-snps-arc@lists.infradead.org Cc: Arnd Bergmann Signed-off-by: Vineet Gupta Signed-off-by: Sasha Levin

ARC: entry: fix syscall_trace_exit argument

2022-04-27T11:53:55Z

commit b1c6ecfdd06907554518ec384ce8e99889d15193 upstream. Function syscall_trace_exit expects pointer to pt_regs. However r0 is also used to keep syscall return value. Restore pointer to pt_regs before calling syscall_trace_exit. Cc: Signed-off-by: Sergey Matyukevich Signed-off-by: Vineet Gupta Signed-off-by: Greg Kroah-Hartman