[PATCH v3 1/4] mm: modify pte format for Svnapot
panqinglin2020 at iscas.ac.cn
panqinglin2020 at iscas.ac.cn
Mon Aug 22 05:59:01 PDT 2022
From: Qinglin Pan <panqinglin2020 at iscas.ac.cn>
This commit adds two erratas to enable/disable svnapot support, patches code
dynamicly when "svnapot" is in the "riscv,isa" field of fdt and SVNAPOT compile
option is set. It will influence the behavior of has_svnapot function and
pte_pfn function. All code dependent on svnapot should make sure that has_svnapot
return true firstly.
Also, this commit modifies PTE definition for Svnapot, and creates some functions in
pgtable.h to mark a PTE as napot and check if it is a Svnapot PTE.
Until now, only 64KB napot size is supported in draft spec, so some macros
has only 64KB version.
Signed-off-by: Qinglin Pan <panqinglin2020 at iscas.ac.cn>
diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index ed66c31e4655..c43708ae7f38 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -432,6 +432,13 @@ config FPU
If you don't know what to do here, say Y.
+config SVNAPOT
+ bool "Svnapot support"
+ default n
+ help
+ Select if your CPU supports Svnapot and you want to enable it when
+ kernel is booting.
+
endmenu # "Platform type"
menu "Kernel features"
diff --git a/arch/riscv/include/asm/errata_list.h b/arch/riscv/include/asm/errata_list.h
index 19a771085781..f22723174cd9 100644
--- a/arch/riscv/include/asm/errata_list.h
+++ b/arch/riscv/include/asm/errata_list.h
@@ -22,7 +22,8 @@
#define CPUFEATURE_SVPBMT 0
#define CPUFEATURE_ZICBOM 1
-#define CPUFEATURE_NUMBER 2
+#define CPUFEATURE_SVNAPOT 2
+#define CPUFEATURE_NUMBER 3
#ifdef __ASSEMBLY__
@@ -142,6 +143,27 @@ asm volatile(ALTERNATIVE_2( \
"r"((unsigned long)(_start) + (_size)) \
: "a0")
+#define ALT_SVNAPOT(_val) \
+asm(ALTERNATIVE("li %0, 0", "li %0, 1", 0, \
+ CPUFEATURE_SVNAPOT, CONFIG_SVNAPOT) \
+ : "=r"(_val) :)
+
+#define ALT_SVNAPOT_PTE_PFN(_val, _napot_shift, _pfn_mask, _pfn_shift) \
+asm(ALTERNATIVE("and %0, %1, %2\n\t" \
+ "srli %0, %0, %3\n\t" \
+ "nop\n\tnop\n\tnop", \
+ "srli t3, %1, %4\n\t" \
+ "and %0, %1, %2\n\t" \
+ "srli %0, %0, %3\n\t" \
+ "sub t4, %0, t3\n\t" \
+ "and %0, %0, t4", \
+ 0, CPUFEATURE_SVNAPOT, CONFIG_SVNAPOT) \
+ : "+r"(_val) \
+ : "r"(_val), \
+ "r"(_pfn_mask), \
+ "i"(_pfn_shift), \
+ "i"(_napot_shift))
+
#endif /* __ASSEMBLY__ */
#endif
diff --git a/arch/riscv/include/asm/hwcap.h b/arch/riscv/include/asm/hwcap.h
index 6f59ec64175e..e4c7ce5a7e1a 100644
--- a/arch/riscv/include/asm/hwcap.h
+++ b/arch/riscv/include/asm/hwcap.h
@@ -58,6 +58,7 @@ enum riscv_isa_ext_id {
RISCV_ISA_EXT_ZICBOM,
RISCV_ISA_EXT_ZIHINTPAUSE,
RISCV_ISA_EXT_SSTC,
+ RISCV_ISA_EXT_SVNAPOT,
RISCV_ISA_EXT_ID_MAX = RISCV_ISA_EXT_MAX,
};
diff --git a/arch/riscv/include/asm/pgtable-64.h b/arch/riscv/include/asm/pgtable-64.h
index dc42375c2357..a23b71cf5979 100644
--- a/arch/riscv/include/asm/pgtable-64.h
+++ b/arch/riscv/include/asm/pgtable-64.h
@@ -74,6 +74,20 @@ typedef struct {
*/
#define _PAGE_PFN_MASK GENMASK(53, 10)
+/*
+ * [63] Svnapot definitions:
+ * 0 Svnapot disabled
+ * 1 Svnapot enabled
+ */
+#define _PAGE_NAPOT_SHIFT 63
+#define _PAGE_NAPOT (1UL << _PAGE_NAPOT_SHIFT)
+#define NAPOT_CONT64KB_ORDER 4UL
+#define NAPOT_CONT64KB_SHIFT (NAPOT_CONT64KB_ORDER + PAGE_SHIFT)
+#define NAPOT_CONT64KB_SIZE (1UL << NAPOT_CONT64KB_SHIFT)
+#define NAPOT_CONT64KB_MASK (NAPOT_CONT64KB_SIZE - 1)
+#define NAPOT_64KB_PTE_NUM (1UL << NAPOT_CONT64KB_ORDER)
+#define NAPOT_64KB_MASK (7UL << _PAGE_PFN_SHIFT)
+
/*
* [62:61] Svpbmt Memory Type definitions:
*
diff --git a/arch/riscv/include/asm/pgtable.h b/arch/riscv/include/asm/pgtable.h
index 7ec936910a96..8be197edaac8 100644
--- a/arch/riscv/include/asm/pgtable.h
+++ b/arch/riscv/include/asm/pgtable.h
@@ -264,10 +264,38 @@ static inline pte_t pud_pte(pud_t pud)
return __pte(pud_val(pud));
}
+static inline bool has_svnapot(void) {
+ u64 _val;
+ ALT_SVNAPOT(_val);
+ return _val;
+}
+
+#ifdef CONFIG_SVNAPOT
+
+static inline unsigned long pte_napot(pte_t pte)
+{
+ return pte_val(pte) & _PAGE_NAPOT;
+}
+
+static inline pte_t pte_mknapot(pte_t pte, unsigned int order)
+{
+ unsigned long napot_bits = (1UL << (order - 1)) << _PAGE_PFN_SHIFT;
+ unsigned long lower_prot =
+ pte_val(pte) & ((1UL << _PAGE_PFN_SHIFT) - 1UL);
+ unsigned long upper_prot = (pte_val(pte) >> _PAGE_PFN_SHIFT)
+ << _PAGE_PFN_SHIFT;
+
+ return __pte(upper_prot | napot_bits | lower_prot | _PAGE_NAPOT);
+}
+#endif /* CONFIG_SVNAPOT */
+
/* Yields the page frame number (PFN) of a page table entry */
static inline unsigned long pte_pfn(pte_t pte)
{
- return __page_val_to_pfn(pte_val(pte));
+ unsigned long _val = pte_val(pte);
+ ALT_SVNAPOT_PTE_PFN(_val, _PAGE_NAPOT_SHIFT,
+ _PAGE_PFN_MASK, _PAGE_PFN_SHIFT);
+ return _val;
}
#define pte_page(x) pfn_to_page(pte_pfn(x))
diff --git a/arch/riscv/kernel/cpu.c b/arch/riscv/kernel/cpu.c
index 0be8a2403212..d2a61122c595 100644
--- a/arch/riscv/kernel/cpu.c
+++ b/arch/riscv/kernel/cpu.c
@@ -96,6 +96,7 @@ static struct riscv_isa_ext_data isa_ext_arr[] = {
__RISCV_ISA_EXT_DATA(zicbom, RISCV_ISA_EXT_ZICBOM),
__RISCV_ISA_EXT_DATA(zihintpause, RISCV_ISA_EXT_ZIHINTPAUSE),
__RISCV_ISA_EXT_DATA(sstc, RISCV_ISA_EXT_SSTC),
+ __RISCV_ISA_EXT_DATA(svnapot, RISCV_ISA_EXT_SVNAPOT),
__RISCV_ISA_EXT_DATA("", RISCV_ISA_EXT_MAX),
};
diff --git a/arch/riscv/kernel/cpufeature.c b/arch/riscv/kernel/cpufeature.c
index 553d755483ed..3f20a5521acb 100644
--- a/arch/riscv/kernel/cpufeature.c
+++ b/arch/riscv/kernel/cpufeature.c
@@ -204,6 +204,7 @@ void __init riscv_fill_hwcap(void)
SET_ISA_EXT_MAP("zicbom", RISCV_ISA_EXT_ZICBOM);
SET_ISA_EXT_MAP("zihintpause", RISCV_ISA_EXT_ZIHINTPAUSE);
SET_ISA_EXT_MAP("sstc", RISCV_ISA_EXT_SSTC);
+ SET_ISA_EXT_MAP("svnapot", RISCV_ISA_EXT_SVNAPOT);
}
#undef SET_ISA_EXT_MAP
}
@@ -283,6 +284,19 @@ static bool __init_or_module cpufeature_probe_zicbom(unsigned int stage)
return false;
}
+static bool __init_or_module cpufeature_probe_svnapot(unsigned int stage)
+{
+#ifdef CONFIG_SVNAPOT
+ switch (stage) {
+ case RISCV_ALTERNATIVES_EARLY_BOOT:
+ return false;
+ default:
+ return riscv_isa_extension_available(NULL, SVNAPOT);
+ }
+#endif
+
+ return false;
+}
/*
* Probe presence of individual extensions.
@@ -301,6 +315,9 @@ static u32 __init_or_module cpufeature_probe(unsigned int stage)
if (cpufeature_probe_zicbom(stage))
cpu_req_feature |= (1U << CPUFEATURE_ZICBOM);
+ if (cpufeature_probe_svnapot(stage))
+ cpu_req_feature |= (1U << CPUFEATURE_SVNAPOT);
+
return cpu_req_feature;
}
--
2.35.1
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