Hi Zhenhua,
On 2023/3/10 10:02, Zhenhua Huang wrote:
Kfence only needs its pool to be mapped as page granularity, previous
judgement was a bit over protected. Decouple it from judgement and do
page granularity mapping for kfence pool only [1].
To implement this, also relocate the kfence pool allocation before the
linear mapping setting up, arm64_kfence_alloc_pool is to allocate phys
addr, __kfence_pool is to be set after linear mapping set up.
We do the same way in our 5.10 kernel, a minor comment below,
LINK: [1] https://lore.kernel.org/linux-arm-kernel/1675750519-1064-1-git-send-email-quic_zhenhuah@xxxxxxxxxxx/T/
Suggested-by: Mark Rutland <mark.rutland@xxxxxxx>
Signed-off-by: Zhenhua Huang <quic_zhenhuah@xxxxxxxxxxx>
---
arch/arm64/mm/mmu.c | 44 ++++++++++++++++++++++++++++++++++++++++++++
arch/arm64/mm/pageattr.c | 5 ++---
include/linux/kfence.h | 8 ++++++++
mm/kfence/core.c | 9 +++++++++
4 files changed, 63 insertions(+), 3 deletions(-)
diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
index 6f9d889..9f06a29e 100644
--- a/arch/arm64/mm/mmu.c
+++ b/arch/arm64/mm/mmu.c
@@ -24,6 +24,7 @@
#include <linux/mm.h>
#include <linux/vmalloc.h>
#include <linux/set_memory.h>
+#include <linux/kfence.h>
#include <asm/barrier.h>
#include <asm/cputype.h>
@@ -525,6 +526,33 @@ static int __init enable_crash_mem_map(char *arg)
}
early_param("crashkernel", enable_crash_mem_map);
+#ifdef CONFIG_KFENCE
+
+static phys_addr_t arm64_kfence_alloc_pool(void)
+{
+ phys_addr_t kfence_pool = 0;
The kfence_pool is no need to be initialized.
+
+ if (!kfence_sample_interval)
+ return (phys_addr_t)NULL;
And one more missing case, kfence support late int, see commit
b33f778bba5e ("kfence: alloc kfence_pool after system startup"),
this changes will break this feature, we add a new cmdline to alloc
kfence_pool regardless of kfence_sample_interval value, maybe there some
other way to deal with this issue.
+
+ kfence_pool = memblock_phys_alloc(KFENCE_POOL_SIZE, PAGE_SIZE);
+ if (!kfence_pool) {
+ pr_err("failed to allocate kfence pool\n");
+ return (phys_addr_t)NULL;
no need this return;
+ }
+
+ return kfence_pool;
+}
+
+#else
+
+static phys_addr_t arm64_kfence_alloc_pool(void)
+{
+ return (phys_addr_t)NULL;
+}
+
+#endif
+
I like all of '(phys_addr_t)NULL' to 0
static void __init map_mem(pgd_t *pgdp)
{
static const u64 direct_map_end = _PAGE_END(VA_BITS_MIN);
@@ -532,6 +560,7 @@ static void __init map_mem(pgd_t *pgdp)
phys_addr_t kernel_end = __pa_symbol(__init_begin);
phys_addr_t start, end;
int flags = NO_EXEC_MAPPINGS;
+ phys_addr_t kfence_pool = 0;
it's no need to be initialized too.
u64 i;
/*
@@ -564,6 +593,10 @@ static void __init map_mem(pgd_t *pgdp)
}
#endif
+ kfence_pool = arm64_kfence_alloc_pool();
+ if (kfence_pool)
+ memblock_mark_nomap(kfence_pool, KFENCE_POOL_SIZE);
+
/* map all the memory banks */
for_each_mem_range(i, &start, &end) {
if (start >= end)
@@ -608,6 +641,17 @@ static void __init map_mem(pgd_t *pgdp)
}
}
#endif
+
+ /* Kfence pool needs page-level mapping */
+ if (kfence_pool) {
+ __map_memblock(pgdp, kfence_pool,
+ kfence_pool + KFENCE_POOL_SIZE,
+ pgprot_tagged(PAGE_KERNEL),
+ NO_BLOCK_MAPPINGS | NO_CONT_MAPPINGS);
+ memblock_clear_nomap(kfence_pool, KFENCE_POOL_SIZE);
+ /* kfence_pool really mapped now */
+ kfence_set_pool(kfence_pool);
+ }
}
