[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [PATCH v6 1/3] xen/arm: add support for run_in_exception_handler()
On 21.01.21 08:55, Jan Beulich wrote: On 20.01.2021 19:20, Julien Grall wrote:On 16/01/2021 10:33, Juergen Gross wrote:Add support to run a function in an exception handler for Arm. Do it as on x86 via a bug_frame, but pass the function pointer via a register (this needs to be done that way, because inline asm support for 32-bit Arm lacks the needed functionality to reference an arbitrary function via the bugframe).I was going to commit the series, but then realized the commit message and comment needs some tweaking because technically GCC is supporting 'i' (I managed to get it working with -fno-pie). So how about: "This is needed to be done that way because GCC complains about invalid constraint when using a function pointer with "i" and PIE is enabled (default on most of GCC shipped with distro). Clang happily accepts it, so it may be a bug in GCC."May I ask why you think it's a bug in gcc? I'd rather consider it a bug in clang. Taking the address of a symbol doesn't yield a constant in PIC or PIE code, aiui. Maybe we should just not add the suspect of a bug in the compiler to either commit message or a comment. It could be a bug in gcc, or just a shortcoming (feature combination not supported). It could be a bug in clang, or clang is clever enough to produce correct code for "i" + PIE. Juergen Attachment:
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