On Wed, Feb 08, 2017 at 10:12:50AM +0100, Peter Zijlstra wrote:
> Something like:
>
> #define EX_REG_HANDLER(_reg) \
> bool ex_handler_value_##_reg(const struct exception_table_entry *fixup, \
> struct pt_regs *regs, int trapnr) \
> { \
> void (*handler)(unsigned long) = \
> (void *)((unsigned long)&fixup->to + fixup->to); \
> \
> if (trapnr != X86_TRAP_UD) \
> return false; \
> \
> regs->ip += 2; /* size of UD2 instruction */ \
> handler(regs->_reg); \
> return true; \
> }
>
> EX_REG_HANDLER(bx);
> EX_REG_HANDLER(cx);
> ...
> EX_REG_HANDLER(ss);
>
>
> asm (
> " .macro reg_to_handler r\n"
> " .irp rs,bx,cx,...,ss\n"
> " .ifc \\r, %\\rs\n"
> " ex_handler_value_\\rs\n"
> " .endif\n"
" .ifc \\r, %e\\rs\n"
" ex_handler_value_\\rs\n"
" .endif\n"
" .ifc \\r, %r\\rs\n"
" ex_handler_value_\\rs\n"
" .endif\n"
> " .endr\n"
> " .endm\n"
> );
to match the 16, 32 and 64 bit names of the same registers. The byte
registers will need additional magic :/
> #define EXCEPTION_VALUE(val, handler) \
> asm volatile ("1: ud2" \
> _ASM_EXTABLE_HANDLE(1b, handler, \
> reg_to_handler %0) \
> : : "r" (val))
>
>
> Where the generic version can simply be:
>
> #define EXCEPTION_VALUE(val, handler) handler((unsigned long)val)
>
>
> Makes sense?
