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| author | Zhenhua Huang <quic_zhenhuah@quicinc.com> | 2023-03-17 16:29:34 +0100 |
|---|---|---|
| committer | Will Deacon <will@kernel.org> | 2023-03-27 17:15:20 +0200 |
| commit | bfa7965b33ab79fc3b2f8adc14704075fe2416cd (patch) | |
| tree | 66be4bf82a2c68a159f9a997c7f7e2dc34174700 /arch/arm64/mm/pageattr.c | |
| parent | Linux 6.3-rc3 (diff) | |
| download | linux-bfa7965b33ab79fc3b2f8adc14704075fe2416cd.tar.xz linux-bfa7965b33ab79fc3b2f8adc14704075fe2416cd.zip | |
mm,kfence: decouple kfence from page granularity mapping judgement
Kfence only needs its pool to be mapped as page granularity, if it is
inited early. Previous judgement was a bit over protected. From [1], Mark
suggested to "just map the KFENCE region a page granularity". So I
decouple it from judgement and do page granularity mapping for kfence
pool only. Need to be noticed that late init of kfence pool still requires
page granularity mapping.
Page granularity mapping in theory cost more(2M per 1GB) memory on arm64
platform. Like what I've tested on QEMU(emulated 1GB RAM) with
gki_defconfig, also turning off rodata protection:
Before:
[root@liebao ]# cat /proc/meminfo
MemTotal: 999484 kB
After:
[root@liebao ]# cat /proc/meminfo
MemTotal: 1001480 kB
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.
LINK: [1] https://lore.kernel.org/linux-arm-kernel/Y+IsdrvDNILA59UN@FVFF77S0Q05N/
Suggested-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Zhenhua Huang <quic_zhenhuah@quicinc.com>
Reviewed-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Reviewed-by: Marco Elver <elver@google.com>
Link: https://lore.kernel.org/r/1679066974-690-1-git-send-email-quic_zhenhuah@quicinc.com
Signed-off-by: Will Deacon <will@kernel.org>
Diffstat (limited to 'arch/arm64/mm/pageattr.c')
| -rw-r--r-- | arch/arm64/mm/pageattr.c | 7 |
1 files changed, 5 insertions, 2 deletions
diff --git a/arch/arm64/mm/pageattr.c b/arch/arm64/mm/pageattr.c index 79dd201c59d8..8e2017ba5f1b 100644 --- a/arch/arm64/mm/pageattr.c +++ b/arch/arm64/mm/pageattr.c @@ -11,6 +11,7 @@ #include <asm/cacheflush.h> #include <asm/set_memory.h> #include <asm/tlbflush.h> +#include <asm/kfence.h> struct page_change_data { pgprot_t set_mask; @@ -22,12 +23,14 @@ bool rodata_full __ro_after_init = IS_ENABLED(CONFIG_RODATA_FULL_DEFAULT_ENABLED bool can_set_direct_map(void) { /* - * rodata_full, DEBUG_PAGEALLOC and KFENCE require linear map to be + * rodata_full and DEBUG_PAGEALLOC require linear map to be * mapped at page granularity, so that it is possible to * protect/unprotect single pages. + * + * KFENCE pool requires page-granular mapping if initialized late. */ return (rodata_enabled && rodata_full) || debug_pagealloc_enabled() || - IS_ENABLED(CONFIG_KFENCE); + arm64_kfence_can_set_direct_map(); } static int change_page_range(pte_t *ptep, unsigned long addr, void *data) |