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accel/tcg: Introduce page_find_range_empty

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Use the interval tree to locate an unused range in the VM.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20230707204054.8792-17-richard.henderson@linaro.org>
This commit is contained in:
Richard Henderson 2023-07-07 21:40:44 +01:00
parent 99982beb4d
commit f2bb7cf299
2 changed files with 56 additions and 0 deletions
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41
accel/tcg/user-exec.c
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@ -605,6 +605,47 @@ bool page_check_range_empty(target_ulong start, target_ulong last)
return pageflags_find(start, last) == NULL;
}
target_ulong page_find_range_empty(target_ulong min, target_ulong max,
target_ulong len, target_ulong align)
{
target_ulong len_m1, align_m1;
assert(min <= max);
assert(max <= GUEST_ADDR_MAX);
assert(len != 0);
assert(is_power_of_2(align));
assert_memory_lock();
len_m1 = len - 1;
align_m1 = align - 1;
/* Iteratively narrow the search region. */
while (1) {
PageFlagsNode *p;
/* Align min and double-check there's enough space remaining. */
min = (min + align_m1) & ~align_m1;
if (min > max) {
return -1;
}
if (len_m1 > max - min) {
return -1;
}
p = pageflags_find(min, min + len_m1);
if (p == NULL) {
/* Found! */
return min;
}
if (max <= p->itree.last) {
/* Existing allocation fills the remainder of the search region. */
return -1;
}
/* Skip across existing allocation. */
min = p->itree.last + 1;
}
}
void page_protect(tb_page_addr_t address)
{
PageFlagsNode *p;