linux-dev/arch/arm/kernel/asm-offsets.c, branch linus/master

ARM: implement THREAD_INFO_IN_TASK for uniprocessor systems

2021-12-06T11:49:17Z

On UP systems, only a single task can be 'current' at the same time, which means we can use a global variable to track it. This means we can also enable THREAD_INFO_IN_TASK for those systems, as in that case, thread_info is accessed via current rather than the other way around, removing the need to store thread_info at the base of the task stack. This, in turn, permits us to enable IRQ stacks and vmap'ed stacks on UP systems as well. To partially mitigate the performance overhead of this arrangement, use a ADD/ADD/LDR sequence with the appropriate PC-relative group relocations to load the value of current when needed. This means that accessing current will still only require a single load as before, avoiding the need for a literal to carry the address of the global variable in each function. However, accessing thread_info will now require this load as well. Acked-by: Linus Walleij Acked-by: Nicolas Pitre Signed-off-by: Ard Biesheuvel Tested-by: Marc Zyngier Tested-by: Vladimir Murzin # ARMv7M

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

gcc-plugins: arm-ssp: Prepare for THREAD_INFO_IN_TASK support

2021-09-27T14:54:01Z

We will be enabling THREAD_INFO_IN_TASK support for ARM, which means that we can no longer load the stack canary value by masking the stack pointer and taking the copy that lives in thread_info. Instead, we will be able to load it from the task_struct directly, by using the TPIDRURO register which will hold the current task pointer when THREAD_INFO_IN_TASK is in effect. This is much more straight-forward, and allows us to declutter this code a bit while at it. Note that this means that ARMv6 (non-v6K) SMP systems can no longer use this feature, but those are quite rare to begin with, so this is a reasonable trade off. Reviewed-by: Kees Cook Signed-off-by: Ard Biesheuvel Reviewed-by: Linus Walleij Tested-by: Amit Daniel Kachhap

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

2021-09-09T20:25:49Z

Pull ARM development updates from Russell King: - Rename "mod_init" and "mod_exit" so that initcall debug output is actually useful (Randy Dunlap) - Update maintainers entries for linux-arm-kernel to indicate it is moderated for non-subscribers (Randy Dunlap) - Move install rules to arch/arm/Makefile (Masahiro Yamada) - Drop unnecessary ARCH_NR_GPIOS definition (Linus Walleij) - Don't warn about atags_to_fdt() stack size (David Heidelberg) - Speed up unaligned copy_{from,to}_kernel_nofault (Arnd Bergmann) - Get rid of set_fs() usage (Arnd Bergmann) - Remove checks for GCC prior to v4.6 (Geert Uytterhoeven) * tag 'for-linus' of git://git.armlinux.org.uk/~rmk/linux-arm: ARM: 9118/1: div64: Remove always-true __div64_const32_is_OK() duplicate ARM: 9117/1: asm-generic: div64: Remove always-true __div64_const32_is_OK() ARM: 9116/1: unified: Remove check for gcc < 4 ARM: 9110/1: oabi-compat: fix oabi epoll sparse warning ARM: 9113/1: uaccess: remove set_fs() implementation ARM: 9112/1: uaccess: add __{get,put}_kernel_nofault ARM: 9111/1: oabi-compat: rework fcntl64() emulation ARM: 9114/1: oabi-compat: rework sys_semtimedop emulation ARM: 9108/1: oabi-compat: rework epoll_wait/epoll_pwait emulation ARM: 9107/1: syscall: always store thread_info->abi_syscall ARM: 9109/1: oabi-compat: add epoll_pwait handler ARM: 9106/1: traps: use get_kernel_nofault instead of set_fs() ARM: 9115/1: mm/maccess: fix unaligned copy_{from,to}_kernel_nofault ARM: 9105/1: atags_to_fdt: don't warn about stack size ARM: 9103/1: Drop ARCH_NR_GPIOS definition ARM: 9102/1: move theinstall rules to arch/arm/Makefile ARM: 9100/1: MAINTAINERS: mark all linux-arm-kernel@infradead list as moderated ARM: 9099/1: crypto: rename 'mod_init' & 'mod_exit' functions to be module-specific

ARM: 9113/1: uaccess: remove set_fs() implementation

2021-08-20T10:39:27Z

There are no remaining callers of set_fs(), so just remove it along with all associated code that operates on thread_info->addr_limit. There are still further optimizations that can be done: - In get_user(), the address check could be moved entirely into the out of line code, rather than passing a constant as an argument, - I assume the DACR handling can be simplified as we now only change it during user access when CONFIG_CPU_SW_DOMAIN_PAN is set, but not during set_fs(). Acked-by: Christoph Hellwig Signed-off-by: Arnd Bergmann Signed-off-by: Russell King (Oracle)

ARM: 9107/1: syscall: always store thread_info->abi_syscall

2021-08-20T10:39:26Z

The system call number is used in a a couple of places, in particular ptrace, seccomp and /proc//syscall. The last one apparently never worked reliably on ARM for tasks that are not currently getting traced. Storing the syscall number in the normal entry path makes it work, as well as allowing us to see if the current system call is for OABI compat mode, which is the next thing I want to hook into. Since the thread_info->syscall field is not just the number any more, it is now renamed to abi_syscall. In kernels that enable both OABI and EABI, the upper bits of this field encode 0x900000 (__NR_OABI_SYSCALL_BASE) for OABI tasks, while normal EABI tasks do not set the upper bits. This makes it possible to implement the in_oabi_syscall() helper later. All other users of thread_info->syscall go through the syscall_get_nr() helper, which in turn filters out the ABI bits. Note that the ABI information is lost with PTRACE_SET_SYSCALL, so one cannot set the internal number to a particular version, but this was already the case. We could change it to let gdb encode the ABI type along with the syscall in a CONFIG_OABI_COMPAT-enabled kernel, but that itself would be a (backwards-compatible) ABI change, so I don't do it here. Acked-by: Christoph Hellwig Signed-off-by: Arnd Bergmann Signed-off-by: Russell King (Oracle)

ARM: ep93xx: remove MaverickCrunch support

2021-08-04T11:30:04Z

The MaverickCrunch support for ep93xx never made it into glibc and was removed from gcc in its 4.8 release in 2012. It is now one of the last parts of arch/arm/ that fails to build with the clang integrated assembler, which is unlikely to ever want to support it. The two alternatives are to force the use of binutils/gas when building the crunch support, or to remove it entirely. According to Hartley Sweeten: "Martin Guy did a lot of work trying to get the maverick crunch working but I was never able to successfully use it for anything. It "kind" of works but depending on the EP93xx silicon revision there are still a number of hardware bugs that either give imprecise or garbage results. I have no problem with removing the kernel support for the maverick crunch." Unless someone else comes up with a good reason to keep it around, remove it now. This touches mostly the ep93xx platform, but removes a bit of code from ARM common ptrace and signal frame handling as well. If there are remaining users of MaverickCrunch, they can use LTS kernels for at least another five years before kernel support ends. Link: https://lore.kernel.org/linux-arm-kernel/20210802141245.1146772-1-arnd@kernel.org/ Link: https://lore.kernel.org/linux-arm-kernel/20210226164345.3889993-1-arnd@kernel.org/ Link: https://github.com/ClangBuiltLinux/linux/issues/1272 Link: https://gcc.gnu.org/legacy-ml/gcc/2008-03/msg01063.html Cc: "Martin Guy" Signed-off-by: Arnd Bergmann

ARM: 9075/1: kernel: Fix interrupted SMC calls

2021-04-18T18:15:14Z

On Qualcomm ARM32 platforms, the SMC call can return before it has completed. If this occurs, the call can be restarted, but it requires using the returned session ID value from the interrupted SMC call. The ARM32 SMCC code already has the provision to add platform specific quirks for things like this. So let's make use of it and add the Qualcomm specific quirk (ARM_SMCCC_QUIRK_QCOM_A6) used by the QCOM_SCM driver. This change is similar to the below one added for ARM64 a while ago: commit 82bcd087029f ("firmware: qcom: scm: Fix interrupted SCM calls") Without this change, the Qualcomm ARM32 platforms like SDX55 will return -EINVAL for SMC calls used for modem firmware loading and validation. Signed-off-by: Manivannan Sadhasivam Reviewed-by: Bjorn Andersson Signed-off-by: Russell King

ARM: kexec: fix oops after TLB are invalidated

2021-02-05T10:23:29Z

Giancarlo Ferrari reports the following oops while trying to use kexec: Unable to handle kernel paging request at virtual address 80112f38 pgd = fd7ef03e [80112f38] *pgd=0001141e(bad) Internal error: Oops: 80d [#1] PREEMPT SMP ARM ... This is caused by machine_kexec() trying to set the kernel text to be read/write, so it can poke values into the relocation code before copying it - and an interrupt occuring which changes the page tables. The subsequent writes then hit read-only sections that trigger a data abort resulting in the above oops. Fix this by copying the relocation code, and then writing the variables into the destination, thereby avoiding the need to make the kernel text read/write. Reported-by: Giancarlo Ferrari Tested-by: Giancarlo Ferrari Signed-off-by: Russell King

Raise gcc version requirement to 4.9

2020-07-08T17:48:35Z

I realize that we fairly recently raised it to 4.8, but the fact is, 4.9 is a much better minimum version to target. We have a number of workarounds for actual bugs in pre-4.9 gcc versions (including things like internal compiler errors on ARM), but we also have some syntactic workarounds for lacking features. In particular, raising the minimum to 4.9 means that we can now just assume _Generic() exists, which is likely the much better replacement for a lot of very convoluted built-time magic with conditionals on sizeof and/or __builtin_choose_expr() with same_type() etc. Using _Generic also means that you will need to have a very recent version of 'sparse', but thats easy to build yourself, and much less of a hassle than some old gcc version can be. The latest (in a long string) of reasons for minimum compiler version upgrades was commit 5435f73d5c4a ("efi/x86: Fix build with gcc 4"). Ard points out that RHEL 7 uses gcc-4.8, but the people who stay back on old RHEL versions persumably also don't build their own kernels anyway. And maybe they should cross-built or just have a little side affair with a newer compiler? Acked-by: Ard Biesheuvel Acked-by: Peter Zijlstra Signed-off-by: Linus Torvalds