Alex Bennée <alex.ben...@linaro.org> writes:
> This tries to simplify the init_guest_space code to be a little less
> convoluted and remove the brute force mapping algorithm that gets
> tripped up so badly by the sanitizers.
>
> We first try to do what is requested by the host. Failing that we try
> and satisfy the guest requested base address. If all those options
> fail we fall back to finding a space in the memory map using our
> recently written read_self_maps() helper.
>
> Less mind-binding gotos and hopefully clearer logic although perhaps
> more sloppy casting than I'm totally happy with.
>
> Signed-off-by: Alex Bennée <alex.ben...@linaro.org>
> ---
> linux-user/elfload.c | 279 +++++++++++++++++++------------------------
> 1 file changed, 125 insertions(+), 154 deletions(-)
Richard,
I think I overthought the magic alignment code as we can deal with it
all in advance and not have to add extra pages which might get in the
way:
1 file changed, 5 insertions(+), 7 deletions(-)
linux-user/elfload.c | 12 +++++-------
modified linux-user/elfload.c
@@ -2169,17 +2169,15 @@ unsigned long init_guest_space(unsigned long host_start,
* that will accept the initial mapping as well as being able to
* map the (ARM32 specific) commpage later.
*
- * We need to ensure the address is properly aligned. But this
- * does mean that there is a padding of < 1 page both before and
- * after the aligned range; the "after" could could cause problems
- * for aforementioned ARM32 emulation.
+ * We need to ensure the address is properly aligned but we can
+ * take that into account when looking for the gap.
*/
{
#if defined(TARGET_ARM) && !defined(TARGET_AARCH64)
uint64_t required_size =
(0xffff0f00 & qemu_host_page_mask) + qemu_host_page_size;
#else
- uint64_t required_size = host_size + align;
+ uint64_t required_size = host_size;
#endif
GSList *map_info = read_self_maps();
GSList *last, *next;
@@ -2211,10 +2209,10 @@ unsigned long init_guest_space(unsigned long host_start,
* From this point on it should be a formality but lets go through
* the steps anyway.
*/
- if (mmap(map_addr, host_size + align , PROT_NONE,
+ if (mmap(map_addr, host_size, PROT_NONE,
flags | MAP_FIXED, -1, 0) == map_addr) {
unsigned long addr = (unsigned long) map_addr;
- if (!check_commpage(addr, host_size + align)) {
+ if (!check_commpage(addr, host_size)) {
error_report("%s: commpage won't fit in guest_memory @ %p",
__func__, map_addr);
abort();
--
Alex Bennée
