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lmb: check if a region can be reserved by lmb_reserve()

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The logic used in lmb_alloc() takes into consideration the existing
reserved regions, and ensures that the allocated region does not
overlap with any existing allocated regions. The lmb_reserve()
function is not doing any such checks -- the requested region might
overlap with an existing region. This also shows up with
lmb_alloc_addr() as this function ends up calling lmb_reserve().

Add a function which checks if the region requested is overlapping
with an existing reserved region, and allow for the reservation to
happen only if both the regions have LMB_NONE flag, which allows
re-requesting of the region. In any other scenario of an overlap, have
lmb_reserve() return -EEXIST, implying that the requested region is
already reserved.

Add corresponding test cases which check for overlapping reservation
requests made through lmb_reserve() and lmb_alloc_addr(). And while
here, fix some of the comments in the test function being touched.

Signed-off-by: Sughosh Ganu <sughosh.ganu@linaro.org>
Reviewed-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
This commit is contained in:
Sughosh Ganu 2025-03-03 19:02:26 +05:30 • committed by Tom Rini
parent 9943015f1b
commit 56f186a68b
2 changed files with 146 additions and 4 deletions
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36
lib/lmb.c
View file

@ -561,6 +561,39 @@ static __maybe_unused void lmb_reserve_common_spl(void)
}
}
/**
* lmb_can_reserve_region() - check if the region can be reserved
* @base: base address of region to be reserved
* @size: size of region to be reserved
* @flags: flag of the region to be reserved
*
* Go through all the reserved regions and ensure that the requested
* region does not overlap with any existing regions. An overlap is
* allowed only when the flag of the request region and the existing
* region is LMB_NONE.
*
* Return: true if region can be reserved, false otherwise
*/
static bool lmb_can_reserve_region(phys_addr_t base, phys_size_t size,
u32 flags)
{
uint i;
struct lmb_region *lmb_reserved = lmb.used_mem.data;
for (i = 0; i < lmb.used_mem.count; i++) {
u32 rgnflags = lmb_reserved[i].flags;
phys_addr_t rgnbase = lmb_reserved[i].base;
phys_size_t rgnsize = lmb_reserved[i].size;
if (lmb_addrs_overlap(base, size, rgnbase, rgnsize)) {
if (flags != LMB_NONE || flags != rgnflags)
return false;
}
}
return true;
}
void lmb_add_memory(void)
{
int i;
@ -633,6 +666,9 @@ long lmb_reserve(phys_addr_t base, phys_size_t size, u32 flags)
long ret = 0;
struct alist *lmb_rgn_lst = &lmb.used_mem;
if (!lmb_can_reserve_region(base, size, flags))
return -EEXIST;
ret = lmb_add_region_flags(lmb_rgn_lst, base, size, flags);
if (ret)
return ret;

114
test/lib/lmb.c
View file

@ -471,17 +471,17 @@ static int lib_test_lmb_overlapping_reserve(struct unit_test_state *uts)
ASSERT_LMB(mem_lst, used_lst, ram, ram_size, 1, 0x40010000, 0x10000,
0, 0, 0, 0);
/* allocate overlapping region should return the coalesced count */
/* allocate overlapping region */
ret = lmb_reserve(0x40011000, 0x10000, LMB_NONE);
ut_asserteq(ret, 0);
ASSERT_LMB(mem_lst, used_lst, ram, ram_size, 1, 0x40010000, 0x11000,
0, 0, 0, 0);
/* allocate 3nd region */
/* allocate 2nd region */
ret = lmb_reserve(0x40030000, 0x10000, LMB_NONE);
ut_asserteq(ret, 0);
ASSERT_LMB(mem_lst, used_lst, ram, ram_size, 2, 0x40010000, 0x11000,
0x40030000, 0x10000, 0, 0);
/* allocate 2nd region , This should coalesced all region into one */
/* allocate 3rd region , This should coalesce all regions into one */
ret = lmb_reserve(0x40020000, 0x10000, LMB_NONE);
ut_assert(ret >= 0);
ASSERT_LMB(mem_lst, used_lst, ram, ram_size, 1, 0x40010000, 0x30000,
@ -499,6 +499,41 @@ static int lib_test_lmb_overlapping_reserve(struct unit_test_state *uts)
ASSERT_LMB(mem_lst, used_lst, ram, ram_size, 1, 0x40000000, 0x40000,
0, 0, 0, 0);
/* try to allocate overlapping region with a different flag, should fail */
ret = lmb_reserve(0x40008000, 0x1000, LMB_NOOVERWRITE);
ut_asserteq(ret, -EEXIST);
/* allocate another region at 0x40050000 with a different flag */
ret = lmb_reserve(0x40050000, 0x10000, LMB_NOOVERWRITE);
ut_asserteq(ret, 0);
ASSERT_LMB(mem_lst, used_lst, ram, ram_size, 2, 0x40000000, 0x40000,
0x40050000, 0x10000, 0, 0);
/*
* try to reserve a region adjacent to region 1 overlapping the 2nd region,
* should fail
*/
ret = lmb_reserve(0x40040000, 0x20000, LMB_NONE);
ut_asserteq(ret, -EEXIST);
/*
* try to reserve a region between the two regions, but without an overlap,
* should succeed. this added region coalesces with the region 1
*/
ret = lmb_reserve(0x40040000, 0x10000, LMB_NONE);
ut_asserteq(ret, 0);
ASSERT_LMB(mem_lst, used_lst, ram, ram_size, 2, 0x40000000, 0x50000,
0x40050000, 0x10000, 0, 0);
/*
* try to reserve a region which overlaps with both the regions,
* should fail as the flags do not match
*/
ret = lmb_reserve(0x40020000, 0x80000, LMB_NONE);
ut_asserteq(ret, -EEXIST);
ASSERT_LMB(mem_lst, used_lst, ram, ram_size, 2, 0x40000000, 0x50000,
0x40050000, 0x10000, 0, 0);
lmb_pop(&store);
return 0;
@ -549,6 +584,77 @@ static int test_alloc_addr(struct unit_test_state *uts, const phys_addr_t ram)
ret = lmb_free(alloc_addr_a, 0x1000);
ut_asserteq(ret, 0);
/*
* Add two regions with different flags, region1 and region2 with
* a gap between them.
* Try adding another region, adjacent to region 1 and overlapping
* region 2. Should fail.
*/
a = lmb_alloc_addr(alloc_addr_a, 0x1000, LMB_NONE);
ut_asserteq(a, alloc_addr_a);
b = lmb_alloc_addr(alloc_addr_a + 0x4000, 0x1000, LMB_NOOVERWRITE);
ut_asserteq(b, alloc_addr_a + 0x4000);
ASSERT_LMB(mem_lst, used_lst, ram, ram_size, 2, a, 0x1000,
b, 0x1000, 0, 0);
c = lmb_alloc_addr(alloc_addr_a + 0x1000, 0x5000, LMB_NONE);
ut_asserteq(c, 0);
ASSERT_LMB(mem_lst, used_lst, ram, ram_size, 2, a, 0x1000,
b, 0x1000, 0, 0);
ret = lmb_free(a, 0x1000);
ut_asserteq(ret, 0);
ret = lmb_free(b, 0x1000);
ut_asserteq(ret, 0);
/*
* Add two regions with same flags(LMB_NONE), region1 and region2
* with a gap between them.
* Try adding another region, adjacent to region 1 and overlapping
* region 2. Should succeed. All regions should coalesce into a
* single region.
*/
a = lmb_alloc_addr(alloc_addr_a, 0x1000, LMB_NONE);
ut_asserteq(a, alloc_addr_a);
b = lmb_alloc_addr(alloc_addr_a + 0x4000, 0x1000, LMB_NONE);
ut_asserteq(b, alloc_addr_a + 0x4000);
ASSERT_LMB(mem_lst, used_lst, ram, ram_size, 2, a, 0x1000,
b, 0x1000, 0, 0);
c = lmb_alloc_addr(alloc_addr_a + 0x1000, 0x5000, LMB_NONE);
ut_asserteq(c, alloc_addr_a + 0x1000);
ASSERT_LMB(mem_lst, used_lst, ram, ram_size, 1, a, 0x6000,
0, 0, 0, 0);
ret = lmb_free(a, 0x6000);
ut_asserteq(ret, 0);
/*
* Add two regions with same flags(LMB_NOOVERWRITE), region1 and
* region2 with a gap between them.
* Try adding another region, adjacent to region 1 and overlapping
* region 2. Should fail.
*/
a = lmb_alloc_addr(alloc_addr_a, 0x1000, LMB_NOOVERWRITE);
ut_asserteq(a, alloc_addr_a);
b = lmb_alloc_addr(alloc_addr_a + 0x4000, 0x1000, LMB_NOOVERWRITE);
ut_asserteq(b, alloc_addr_a + 0x4000);
ASSERT_LMB(mem_lst, used_lst, ram, ram_size, 2, a, 0x1000,
b, 0x1000, 0, 0);
c = lmb_alloc_addr(alloc_addr_a + 0x1000, 0x5000, LMB_NOOVERWRITE);
ut_asserteq(c, 0);
ASSERT_LMB(mem_lst, used_lst, ram, ram_size, 2, a, 0x1000,
b, 0x1000, 0, 0);
ret = lmb_free(a, 0x1000);
ut_asserteq(ret, 0);
ret = lmb_free(b, 0x1000);
ut_asserteq(ret, 0);
/* reserve 3 blocks */
ret = lmb_reserve(alloc_addr_a, 0x10000, LMB_NONE);
ut_asserteq(ret, 0);
@ -760,7 +866,7 @@ static int lib_test_lmb_flags(struct unit_test_state *uts)
/* reserve again, new flag */
ret = lmb_reserve(0x40010000, 0x10000, LMB_NONE);
ut_asserteq(ret, -1);
ut_asserteq(ret, -EEXIST);
ASSERT_LMB(mem_lst, used_lst, ram, ram_size, 1, 0x40010000, 0x10000,
0, 0, 0, 0);