Messages in this thread | | | Date | Thu, 19 Oct 2023 15:27:52 +0100 | From | Mark Rutland <> | Subject | Re: [PATCH 2/4] arm64/process: Make loading of 32bit processes depend on aarch32_enabled() |
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On Thu, Oct 19, 2023 at 02:38:32PM +0200, Andrea della Porta wrote: > On 13:52 Wed 18 Oct , Mark Rutland wrote: > > On Wed, Oct 18, 2023 at 01:13:20PM +0200, Andrea della Porta wrote: > > > Major aspect of Aarch32 emulation is the ability to load 32bit > > > processes. > > > That's currently decided (among others) by compat_elf_check_arch(). > > > > > > Make the macro use aarch32_enabled() to decide if Aarch32 compat is > > > enabled before loading a 32bit process. > > > > > > Signed-off-by: Andrea della Porta <andrea.porta@suse.com> > > > > Why can't you make system_supports_32bit_el0() take the option into account > > instead? > > > > I may be wrong here, but it seems to me that system_supports_32bit_el0() > answers teh question "can this system supports compat execution?" rather than > "do I want this system to run any compat execution?". That's the point of > aarch32_enabled(), to state whether we want teh system to run A32 code or not, > regardless of the system supporting it (of course, if the system does not > support A32 in EL0, this is a no-no, but that's another story).
That's what the implementation does today, but we're really using it as a "do we intend for 32-bit EL0 to work?" predicate, and generally the system_supports_${FEATURE}() helpers are affected by the combination of actual HW support, kernel config options, *and* kernel command line options. For example, system_supports_sve() is affected by both CONFIG_ARM64_SVE and the "arm64.nosve" command line option.
Thanks, Mark.
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