kernel.git/arch/arm/kernel/iwmmxt.S, branch linux-rolling-stable

ARM: 9352/1: iwmmxt: Remove support for PJ4/PJ4B cores

2024-04-03T13:32:33Z

[ Upstream commit b9920fdd5a751df129808e7fa512e9928223ee05 ] PJ4 is a v7 core that incorporates a iWMMXt coprocessor. However, GCC does not support this combination (its iWMMXt configuration always implies v5te), and so there is no v6/v7 user space that actually makes use of this, beyond generic support for things like setjmp() that preserve/restore the iWMMXt register file using generic LDC/STC instructions emitted in assembler. As [0] appears to imply, this logic is triggered for the init process at boot, and so most user threads will have a iWMMXt register context associated with it, even though it is never used. At this point, it is highly unlikely that such GCC support will ever materialize (and Clang does not implement support for iWMMXt to begin with). This means that advertising iWMMXt support on these cores results in context switch overhead without any associated benefit, and so it is better to simply ignore the iWMMXt unit on these systems. So rip out the support. Doing so also fixes the issue reported in [0] related to UNDEF handling of co-processor #0/#1 instructions issued from user space running in Thumb2 mode. The PJ4 cores are used in four platforms: Armada 370/xp, Dove (Cubox, d2plug), MMP2 (xo-1.75) and Berlin (Google TV). Out of these, only the first is still widely used, but that one actually doesn't have iWMMXt but instead has only VFPV3-D16, and so it is not impacted by this change. Closes: https://bugzilla.kernel.org/show_bug.cgi?id=218427 [0] Fixes: 8bcba70cb5c22 ("ARM: entry: Disregard Thumb undef exception ...") Acked-by: Linus Walleij Acked-by: Arnd Bergmann Acked-by: Nicolas Pitre Reviewed-by: Jisheng Zhang Signed-off-by: Ard Biesheuvel Signed-off-by: Russell King (Oracle) Signed-off-by: Sasha Levin

ARM: iwmmxt: Use undef hook to enable coprocessor for task

2023-05-17T13:08:22Z

Define a undef hook to deal with undef exceptions triggered by iwmmxt instructions that were issued with the coprocessor disabled. This removes the dependency on the coprocessor dispatch code in entry-armv.S, which will be made NWFPE-only in a subsequent patch. Reviewed-by: Linus Walleij Signed-off-by: Ard Biesheuvel

ARM: 9029/1: Make iwmmxt.S support Clang's integrated assembler

2020-12-08T10:14:59Z

This patch replaces 6 IWMMXT instructions Clang's integrated assembler does not support in iwmmxt.S using macros, while making sure GNU assembler still emit the same instructions. This should be easier than providing full IWMMXT support in Clang. This is one of the last bits of kernel code that could be compiled but not assembled with clang. Once all of it works with IAS, we no longer need to special-case 32-bit Arm in Kbuild, or turn off CONFIG_IWMMXT when build-testing. "Intel Wireless MMX Technology - Developer Guide - August, 2002" should be referenced for the encoding schemes of these extensions. Link: https://github.com/ClangBuiltLinux/linux/issues/975 Suggested-by: Nick Desaulniers Suggested-by: Ard Biesheuvel Acked-by: Ard Biesheuvel Reviewed-by: Nick Desaulniers Tested-by: Nick Desaulniers Signed-off-by: Jian Cai Signed-off-by: Russell King

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500

2019-06-19T15:09:55Z

Based on 2 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 version 2 as published by the free software foundation this program is free software you can redistribute it and or modify it under the terms of the gnu general public license version 2 as published by the free software foundation # extracted by the scancode license scanner the SPDX license identifier GPL-2.0-only has been chosen to replace the boilerplate/reference in 4122 file(s). Signed-off-by: Thomas Gleixner Reviewed-by: Enrico Weigelt Reviewed-by: Kate Stewart Reviewed-by: Allison Randal Cc: linux-spdx@vger.kernel.org Link: https://lkml.kernel.org/r/20190604081206.933168790@linutronix.de Signed-off-by: Greg Kroah-Hartman

ARM: align .data section

2017-08-14T15:22:55Z

Robert Jarzmik reports that his PXA25x system fails to boot with 4.12, failing at __flush_whole_cache in arch/arm/mm/proc-xscale.S:215: 0xc0019e20 <+0>: ldr r1, [pc, #788] 0xc0019e24 <+4>: ldr r0, [r1] <== here with r1 containing 0xc06f82cd, which is the address of "clean_addr". Examination of the System.map shows: c06f22c8 D user_pmd_table c06f22cc d __warned.19178 c06f22cd d clean_addr indicating that a .data.unlikely section has appeared just before the .data section from proc-xscale.S. According to objdump -h, it appears that our assembly files default their .data alignment to 2**0, which is bad news if the preceding .data section size is not power-of-2 aligned at link time. Add the appropriate .align directives to all assembly files in arch/arm that are missing them where we require an appropriate alignment. Reported-by: Robert Jarzmik Tested-by: Robert Jarzmik Signed-off-by: Russell King

ARM: 8221/1: PJ4: allow building in Thumb-2 mode

2014-12-03T16:08:00Z

Two files that get included when building the multi_v7_defconfig target fail to build when selecting THUMB2_KERNEL for this configuration. In both cases, we can just build the file as ARM code, as none of its symbols are exported to modules, so there are no interworking concerns. In the iwmmxt.S case, add ENDPROC() declarations so the symbols are annotated as functions, resulting in the linker to emit the appropriate mode switches. Acked-by: Nicolas Pitre Tested-by: Olof Johansson Signed-off-by: Ard Biesheuvel Signed-off-by: Russell King

Merge branches 'fixes' and 'misc' into for-next

2014-08-05T09:27:13Z

Conflicts: arch/arm/kernel/iwmmxt.S arch/arm/mm/cache-l2x0.c arch/arm/mm/mmu.c

ARM: 8100/1: Fix preemption disable in iwmmxt_task_enable()

2014-07-18T11:30:14Z

commit 431a84b1a4f7d1a0085d5b91330c5053cc8e8b12 ("ARM: 8034/1: Disable preemption in iwmmxt_task_enable()") introduced macros {inc,dec}_preempt_count to iwmmxt_task_enable to make it run with preemption disabled. Unfortunately, other functions in iwmmxt.S also use concan_{save,dump,load} sections located in iwmmxt_task_enable() to deal with iWMMXt coprocessor. This causes an unbalanced preempt_count due to excessive dec_preempt_count and destroyed return addresses in callers of concan_ labels due to a register collision: Linux version 3.16.0-rc3-00062-gd92a333-dirty (jef@armhf) (gcc version 4.8.3 (Debian 4.8.3-4) ) #5 PREEMPT Thu Jul 3 19:46:39 CEST 2014 CPU: ARMv7 Processor [560f5815] revision 5 (ARMv7), cr=10c5387d CPU: PIPT / VIPT nonaliasing data cache, PIPT instruction cache Machine model: SolidRun CuBox ... PJ4 iWMMXt v2 coprocessor enabled. ... Unable to handle kernel paging request at virtual address fffffffe pgd = bb25c000 [fffffffe] *pgd=3bfde821, *pte=00000000, *ppte=00000000 Internal error: Oops: 80000007 [#1] PREEMPT ARM Modules linked in: CPU: 0 PID: 62 Comm: startpar Not tainted 3.16.0-rc3-00062-gd92a333-dirty #5 task: bb230b80 ti: bb256000 task.ti: bb256000 PC is at 0xfffffffe LR is at iwmmxt_task_copy+0x44/0x4c pc : [] lr : [<800130ac>] psr: 40000033 sp : bb257de8 ip : 00000013 fp : bb257ea4 r10: bb256000 r9 : fffffdfe r8 : 76e898e6 r7 : bb257ec8 r6 : bb256000 r5 : 7ea12760 r4 : 000000a0 r3 : ffffffff r2 : 00000003 r1 : bb257df8 r0 : 00000000 Flags: nZcv IRQs on FIQs on Mode SVC_32 ISA Thumb Segment user Control: 10c5387d Table: 3b25c019 DAC: 00000015 Process startpar (pid: 62, stack limit = 0xbb256248) This patch fixes the issue by moving concan_{save,dump,load} into separate code sections and make iwmmxt_task_enable() call them in the same way the other functions use concan_ symbols. The test for valid ownership is moved to concan_save and is safe for the other user of it, iwmmxt_task_disable(). The register collision is also resolved by moving concan_ symbols as {inc,dec}_preempt_count are now local to iwmmxt_task_enable(). Fixes: 431a84b1a4f7 ("ARM: 8034/1: Disable preemption in iwmmxt_task_enable()") Signed-off-by: Sebastian Hesselbarth Acked-by: Catalin Marinas Reported-by: Jean-Francois Moine Signed-off-by: Russell King

ARM: convert all "mov.* pc, reg" to "bx reg" for ARMv6+

2014-07-18T11:29:04Z

ARMv6 and greater introduced a new instruction ("bx") which can be used to return from function calls. Recent CPUs perform better when the "bx lr" instruction is used rather than the "mov pc, lr" instruction, and this sequence is strongly recommended to be used by the ARM architecture manual (section A.4.1.1). We provide a new macro "ret" with all its variants for the condition code which will resolve to the appropriate instruction. Rather than doing this piecemeal, and miss some instances, change all the "mov pc" instances to use the new macro, with the exception of the "movs" instruction and the kprobes code. This allows us to detect the "mov pc, lr" case and fix it up - and also gives us the possibility of deploying this for other registers depending on the CPU selection. Reported-by: Will Deacon Tested-by: Stephen Warren # Tegra Jetson TK1 Tested-by: Robert Jarzmik # mioa701_bootresume.S Tested-by: Andrew Lunn # Kirkwood Tested-by: Shawn Guo Tested-by: Tony Lindgren # OMAPs Tested-by: Gregory CLEMENT # Armada XP, 375, 385 Acked-by: Sekhar Nori # DaVinci Acked-by: Christoffer Dall # kvm/hyp Acked-by: Haojian Zhuang # PXA3xx Acked-by: Stefano Stabellini # Xen Tested-by: Uwe Kleine-König # ARMv7M Tested-by: Simon Horman # Shmobile Signed-off-by: Russell King

Merge branches 'alignment', 'fixes', 'l2c' (early part) and 'misc' into for-next

2014-06-05T11:35:52Z