Re: [PATCH v2] arm64: jump_label: use constraints "Si" instead of "i"
From: Mark Rutland <mark.rutland@arm.com>
Date: 2024-02-19 18:22:31
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On Mon, Feb 19, 2024 at 06:06:19PM +0100, Arnd Bergmann wrote:
On Mon, Feb 19, 2024, at 16:41, Ard Biesheuvel wrote:quoted
On Mon, 19 Feb 2024 at 15:43, Geert Uytterhoeven [off-list ref] wrote:quoted
On Mon, Feb 19, 2024 at 11:57 AM Ard Biesheuvel [off-list ref] wrote:quoted
On Mon, 19 Feb 2024 at 11:56, Ard Biesheuvel [off-list ref] wrote:quoted
quoted
I could reproduce the issue on v6.8-rc5 using arm64 defconfig and x86_64-gcc-5.5.0-nolibc-aarch64-linux.tar.xz from https://cdn.kernel.org/pub/tools/crosstool/files/bin/x86_64/5.5.0/:OK, I managed to do so as well. And GCC 6.4 from the same source works correctly. Not sure whether there are any plans to bump the minimal GCC version any time soon (cc'ing Arnd), but we should probably drop this change until that happens.From what I can tell, we may as well formally raise the minimum gcc version to 8.1+ already, as that is a version that is actually used in distros, and we have been on 5.1+ for a few years already. Not sure if there are any other benefits to gcc-8 besides allowing minor cleanups.
Arguably a minor cleanup, but on arm64 that'd allow us to get rid of the old mcount-based ftrace implementation and rely on -fpatchable-function-entry. On its own that'd save ~130 lines of asm and ~70 lines of C, but it'd also remove some constraints on other features (e.g. the mcount-based form's graph tracer isn't compatible with pointer authentication), it would simplify a few things going forwards (e.g. the implementation of RELIABLE_STACKTRACE, since we could rely on having ftrace_regs and a single trampoline), and the remaining support would be better tested. I've wanted to remove the old ftrace implementation for a while, but on its own it was never important/urgent enough to justify bumping to GCC 8+. Mark. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel