kernel.git/arch/arm/include/asm/assembler.h, branch linux-5.16.y

ARM: fix co-processor register typo

2022-03-11T11:42:08Z

commit 33970b031dc4653cc9dc80f2886976706c4c8ef1 upstream. In the recent Spectre BHB patches, there was a typo that is only exposed in certain configurations: mcr p15,0,XX,c7,r5,4 should have been mcr p15,0,XX,c7,c5,4 Reported-by: kernel test robot Fixes: b9baf5c8c5c3 ("ARM: Spectre-BHB workaround") Signed-off-by: Russell King (Oracle) Acked-by: Catalin Marinas Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

ARM: Spectre-BHB workaround

2022-03-11T11:42:06Z

commit b9baf5c8c5c356757f4f9d8180b5e9d234065bc3 upstream. Workaround the Spectre BHB issues for Cortex-A15, Cortex-A57, Cortex-A72, Cortex-A73 and Cortex-A75. We also include Brahma B15 as well to be safe, which is affected by Spectre V2 in the same ways as Cortex-A15. Reviewed-by: Catalin Marinas Signed-off-by: Russell King (Oracle) Signed-off-by: Greg Kroah-Hartman

ARM: 9180/1: Thumb2: align ALT_UP() sections in modules sufficiently

2022-02-01T16:29:00Z

commit 9f80ccda53b9417236945bc7ece4b519037df74d upstream. When building for Thumb2, the .alt.smp.init sections that are emitted by the ALT_UP() patching code may not be 32-bit aligned, even though the fixup_smp_on_up() routine expects that. This results in alignment faults at module load time, which need to be fixed up by the fault handler. So let's align those sections explicitly, and prevent this from occurring. Cc: Signed-off-by: Ard Biesheuvel Signed-off-by: Russell King (Oracle) Signed-off-by: Greg Kroah-Hartman

ARM: smp: Enable THREAD_INFO_IN_TASK

2021-09-27T14:54:02Z

Now that we no longer rely on thread_info living at the base of the task stack to be able to access the 'current' pointer, we can wire up the generic support for moving thread_info into the task struct itself. Note that this requires us to update the cpu field in thread_info explicitly, now that the core code no longer does so. Ideally, we would switch the percpu code to access the cpu field in task_struct instead, but this unleashes #include circular dependency hell. Co-developed-by: Keith Packard Signed-off-by: Keith Packard Signed-off-by: Ard Biesheuvel Reviewed-by: Linus Walleij Tested-by: Amit Daniel Kachhap

ARM: smp: Store current pointer in TPIDRURO register if available

2021-09-27T14:54:02Z

Now that the user space TLS register is assigned on every return to user space, we can use it to keep the 'current' pointer while running in the kernel. This removes the need to access it via thread_info, which is located at the base of the stack, but will be moved out of there in a subsequent patch. Use the __builtin_thread_pointer() helper when available - this will help GCC understand that reloading the value within the same function is not necessary, even when using the per-task stack protector (which also generates accesses via the TLS register). For example, the generated code below loads TPIDRURO only once, and uses it to access both the stack canary and the preempt_count fields. : e92d 41f0 stmdb sp!, {r4, r5, r6, r7, r8, lr} ee1d 4f70 mrc 15, 0, r4, cr13, cr0, {3} 4606 mov r6, r0 b094 sub sp, #80 ; 0x50 f8d4 34e8 ldr.w r3, [r4, #1256] ; 0x4e8 <- stack canary 9313 str r3, [sp, #76] ; 0x4c f8d4 8004 ldr.w r8, [r4, #4] <- preempt count Co-developed-by: Keith Packard Signed-off-by: Keith Packard Signed-off-by: Ard Biesheuvel Reviewed-by: Linus Walleij Tested-by: Amit Daniel Kachhap

ARM: 9039/1: assembler: generalize byte swapping macro into rev_l

2021-02-01T19:41:30Z

Take the 4 instruction byte swapping sequence from the decompressor's head.S, and turn it into a rev_l GAS macro for general use. While at it, make it use the 'rev' instruction when compiling for v6 or later. Reviewed-by: Geert Uytterhoeven Tested-by: Geert Uytterhoeven Reviewed-by: Nicolas Pitre Signed-off-by: Ard Biesheuvel Signed-off-by: Russell King

ARM: kernel: use relative references for UP/SMP alternatives

2020-10-28T16:05:39Z

Currently, the .alt.smp.init section contains the virtual addresses of the patch sites. Since patching may occur both before and after switching into virtual mode, this requires some manual handling of the address when applying the UP alternative. Let's simplify this by using relative offsets in the table entries: this allows us to simply add each entry's address to its contents, regardless of whether we are running in virtual mode or not. Reviewed-by: Nicolas Pitre Signed-off-by: Ard Biesheuvel

ARM: assembler: introduce adr_l, ldr_l and str_l macros

2020-10-28T15:59:43Z

Like arm64, ARM supports position independent code sequences that produce symbol references with a greater reach than the ordinary adr/ldr instructions. Since on ARM, the adrl pseudo-instruction is only supported in ARM mode (and not at all when using Clang), having a adr_l macro like we do on arm64 is useful, and increases symmetry as well. Currently, we use open coded instruction sequences involving literals and arithmetic operations. Instead, we can use movw/movt pairs on v7 CPUs, circumventing the D-cache entirely. E.g., on v7+ CPUs, we can emit a PC-relative reference as follows: movw , #:lower16: - (1f + 8) movt , #:upper16: - (1f + 8) 1: add , , pc For older CPUs, we can emit the literal into a subsection, allowing it to be emitted out of line while retaining the ability to perform arithmetic on label offsets. E.g., on pre-v7 CPUs, we can emit a PC-relative reference as follows: ldr , 2f 1: add , , pc .subsection 1 2: .long - (1b + 8) .previous This is allowed by the assembler because, unlike ordinary sections, subsections are combined into a single section in the object file, and so the label references are not true cross-section references that are visible as relocations. (Subsections have been available in binutils since 2004 at least, so they should not cause any issues with older toolchains.) So use the above to implement the macros mov_l, adr_l, ldr_l and str_l, all of which will use movw/movt pairs on v7 and later CPUs, and use PC-relative literals otherwise. Reviewed-by: Nicolas Pitre Reviewed-by: Linus Walleij Signed-off-by: Ard Biesheuvel

Merge tag 'for-linus' of git://git.armlinux.org.uk/~rmk/linux-arm

2020-06-01T22:36:32Z

Pull ARM updates from Russell King: - remove a now unnecessary usage of the KERNEL_DS for sys_oabi_epoll_ctl() - update my email address in a number of drivers - decompressor EFI updates from Ard Biesheuvel - module unwind section handling updates - sparsemem Kconfig cleanups - make act_mm macro respect THREAD_SIZE * tag 'for-linus' of git://git.armlinux.org.uk/~rmk/linux-arm: ARM: 8980/1: Allow either FLATMEM or SPARSEMEM on the multiplatform build ARM: 8979/1: Remove redundant ARCH_SPARSEMEM_DEFAULT setting ARM: 8978/1: mm: make act_mm() respect THREAD_SIZE ARM: decompressor: run decompressor in place if loaded via UEFI ARM: decompressor: move GOT into .data for EFI enabled builds ARM: decompressor: defer loading of the contents of the LC0 structure ARM: decompressor: split off _edata and stack base into separate object ARM: decompressor: move headroom variable out of LC0 ARM: 8976/1: module: allow arch overrides for .init section names ARM: 8975/1: module: fix handling of unwind init sections ARM: 8974/1: use SPARSMEM_STATIC when SPARSEMEM is enabled ARM: 8971/1: replace the sole use of a symbol with its definition ARM: 8969/1: decompressor: simplify libfdt builds Update rmk's email address in various drivers ARM: compat: remove KERNEL_DS usage in sys_oabi_epoll_ctl()

ARM: uaccess: consolidate uaccess asm to asm/uaccess-asm.h

2020-05-03T16:30:24Z

Consolidate the user access assembly code to asm/uaccess-asm.h. This moves the csdb, check_uaccess, uaccess_mask_range_ptr, uaccess_enable, uaccess_disable, uaccess_save, uaccess_restore macros, and creates two new ones for exception entry and exit - uaccess_entry and uaccess_exit. This makes the uaccess_save and uaccess_restore macros private to asm/uaccess-asm.h. Signed-off-by: Russell King