On 03/07/15 12:34, Roger Pau Monne wrote:
> This is just a preparatory change to clean up the code in setup_guest.
> Should not introduce any functional changes.
>
> Signed-off-by: Roger Pau Monné <roger....@citrix.com>
> Cc: Ian Jackson <ian.jack...@eu.citrix.com>
> Cc: Stefano Stabellini <stefano.stabell...@eu.citrix.com>
> Cc: Ian Campbell <ian.campb...@citrix.com>
> Cc: Wei Liu <wei.l...@citrix.com>
Reviewed-by: Andrew Cooper <andrew.coop...@citrix.com>, with one note.
> @@ -576,6 +584,44 @@ static int setup_guest(xc_interface *xch,
> goto error_out;
> }
>
> + /* Insert JMP <rel32> instruction at address 0x0 to reach entry point. */
> + entry_eip = elf_uval(&elf, elf.ehdr, e_entry);
> + if ( entry_eip != 0 )
> + {
> + char *page0 = xc_map_foreign_range(
> + xch, dom, PAGE_SIZE, PROT_READ | PROT_WRITE, 0);
> + if ( page0 == NULL )
> + goto error_out;
> + page0[0] = 0xe9;
> + *(uint32_t *)&page0[1] = entry_eip - 5;
> + munmap(page0, PAGE_SIZE);
> + }
With this series eventually enabling DOMCTL_setvcpucontext properly for
HVM vcpus, this above juggling can be replaced by setting the starting
eip appropriately, which is neater than stuffing a hand-coded
instruction in at 0.
~Andrew
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