[PATCH 1/4] lmb: check if a region can be reserved by lmb_reserve()

[Heinrich Schuchardt]

On 13.02.25 14:11, Sughosh Ganu wrote:
> 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.
> 
> Also add corresponding test cases which checks for overlapping
> reservation requests made through lmb_reserve() and lmb_alloc_addr().
> 
> Signed-off-by: Sughosh Ganu <sughosh.ganu at linaro.org>
> ---
>   lib/lmb.c      |  23 ++++++++++++
>   test/lib/lmb.c | 100 ++++++++++++++++++++++++++++++++++++++++++++++++-
>   2 files changed, 122 insertions(+), 1 deletion(-)
> 
> diff --git a/lib/lmb.c b/lib/lmb.c
> index 7ca44591e1d..aeaf120f57d 100644
> --- a/lib/lmb.c
> +++ b/lib/lmb.c
> @@ -595,6 +595,26 @@ static __maybe_unused void lmb_reserve_common_spl(void)
>   	}
>   }
>   

Every new function should get a Sphinx style description.

> +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;
> +}
> +

This seems to duplicate code in lmb_resize_regions(). Can we reduce the 
code size by using a common function?

Best regards

Heinrich

>   void lmb_add_memory(void)
>   {
>   	int i;
> @@ -667,6 +687,9 @@ 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;
> diff --git a/test/lib/lmb.c b/test/lib/lmb.c
> index fcb5f1af532..6b995c976dd 100644
> --- a/test/lib/lmb.c
> +++ b/test/lib/lmb.c
> @@ -499,6 +499,32 @@ 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 allocate 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 allocate 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);
> +
>   	lmb_pop(&store);
>   
>   	return 0;
> @@ -549,6 +575,78 @@ 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 +858,7 @@ 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);
>