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Message-Id: <20250611053625.352091-2-duanchenghao@kylinos.cn>
Date: Wed, 11 Jun 2025 13:36:21 +0800
From: Chenghao Duan <duanchenghao@...inos.cn>
To: loongarch@...ts.linux.dev,
linux-kernel@...r.kernel.org
Cc: George Guo <guodongtai@...inos.cn>,
Chenghao Duan <duanchenghao@...inos.cn>
Subject: [PATCH v1 1/5] LoongArch: Support fixmap
From: George Guo <guodongtai@...inos.cn>
Support fixmap for Loongarch.
In the functions patch_map and patch_unmap, __set_fixmap are used.
Therefore, remove the __init identifier from these functions.
Signed-off-by: Chenghao Duan <duanchenghao@...inos.cn>
Signed-off-by: George Guo <guodongtai@...inos.cn>
---
arch/loongarch/include/asm/fixmap.h | 2 +
arch/loongarch/kernel/setup.c | 1 +
arch/loongarch/mm/init.c | 111 ++++++++++++++++++++++++++--
3 files changed, 108 insertions(+), 6 deletions(-)
diff --git a/arch/loongarch/include/asm/fixmap.h b/arch/loongarch/include/asm/fixmap.h
index d2e55ae55..b579ad2be 100644
--- a/arch/loongarch/include/asm/fixmap.h
+++ b/arch/loongarch/include/asm/fixmap.h
@@ -13,6 +13,7 @@
enum fixed_addresses {
FIX_HOLE,
FIX_EARLYCON_MEM_BASE,
+ FIX_TEXT_POKE0,
__end_of_fixed_addresses
};
@@ -20,6 +21,7 @@ enum fixed_addresses {
#define FIXADDR_START (FIXADDR_TOP - FIXADDR_SIZE)
#define FIXMAP_PAGE_IO PAGE_KERNEL_SUC
+void __init early_fixmap_init(void);
extern void __set_fixmap(enum fixed_addresses idx,
phys_addr_t phys, pgprot_t flags);
diff --git a/arch/loongarch/kernel/setup.c b/arch/loongarch/kernel/setup.c
index 56934fe58..368786952 100644
--- a/arch/loongarch/kernel/setup.c
+++ b/arch/loongarch/kernel/setup.c
@@ -597,6 +597,7 @@ void __init setup_arch(char **cmdline_p)
memblock_init();
pagetable_init();
bootcmdline_init(cmdline_p);
+ early_fixmap_init();
parse_early_param();
reserve_initrd_mem();
diff --git a/arch/loongarch/mm/init.c b/arch/loongarch/mm/init.c
index 188b52bbb..68abb7bad 100644
--- a/arch/loongarch/mm/init.c
+++ b/arch/loongarch/mm/init.c
@@ -36,6 +36,109 @@
#include <asm/pgalloc.h>
#include <asm/tlb.h>
+#define SPAN_NR_ENTRIES(vstart, vend, shift) \
+ ((((vend) - 1) >> (shift)) - ((vstart) >> (shift)) + 1)
+
+#define NR_BM_PTE_TABLES \
+ SPAN_NR_ENTRIES(FIXADDR_START, FIXADDR_TOP, PMD_SHIFT)
+#define NR_BM_PMD_TABLES \
+ SPAN_NR_ENTRIES(FIXADDR_START, FIXADDR_TOP, PUD_SHIFT)
+
+static_assert(NR_BM_PMD_TABLES == 1);
+
+#define __BM_TABLE_IDX(addr, shift) \
+ (((addr) >> (shift)) - (FIXADDR_START >> (shift)))
+
+#define BM_PTE_TABLE_IDX(addr) __BM_TABLE_IDX(addr, PMD_SHIFT)
+
+static pte_t bm_pte[NR_BM_PTE_TABLES][PTRS_PER_PTE] __page_aligned_bss;
+static pmd_t bm_pmd[PTRS_PER_PMD] __page_aligned_bss __maybe_unused;
+static pud_t bm_pud[PTRS_PER_PUD] __page_aligned_bss __maybe_unused;
+
+static inline pte_t *fixmap_pte(unsigned long addr)
+{
+ return &bm_pte[BM_PTE_TABLE_IDX(addr)][pte_index(addr)];
+}
+
+static void __init early_fixmap_init_pte(pmd_t *pmdp, unsigned long addr)
+{
+ pmd_t pmd = READ_ONCE(*pmdp);
+ pte_t *ptep;
+
+ if (!pmd_present(pmd)) {
+ ptep = bm_pte[BM_PTE_TABLE_IDX(addr)];
+ pmd_populate_kernel(&init_mm, pmdp, ptep);
+ kernel_pte_init(ptep);
+ }
+}
+
+static void __init early_fixmap_init_pmd(pud_t *pudp, unsigned long addr,
+ unsigned long end)
+{
+ unsigned long next;
+ pud_t pud = READ_ONCE(*pudp);
+ pmd_t *pmdp;
+
+ if (pud_none(pud))
+ pud_populate(&init_mm, pudp, bm_pmd);
+
+ pmdp = pmd_offset(pudp, addr);
+
+#ifndef __PAGETABLE_PMD_FOLDED
+ pmd_init(pmdp);
+#endif
+ do {
+ next = pmd_addr_end(addr, end);
+ early_fixmap_init_pte(pmdp, addr);
+ } while (pmdp++, addr = next, addr != end);
+}
+
+static void __init early_fixmap_init_pud(p4d_t *p4dp, unsigned long addr,
+ unsigned long end)
+{
+ p4d_t p4d = READ_ONCE(*p4dp);
+ pud_t *pudp;
+
+#ifndef __PAGETABLE_PUD_FOLDED
+ if (CONFIG_PGTABLE_LEVELS > 3 && !p4d_none(p4d) &&
+ p4d_phys(p4d) != __pa_symbol(bm_pud)) {
+ /*
+ * We only end up here if the kernel mapping and the fixmap
+ * share the top level pgd entry, which should only happen on
+ * 16k/4 levels configurations.
+ */
+ BUG_ON(!IS_ENABLED(CONFIG_PAGE_SIZE_16KB));
+ }
+#endif
+
+ if (p4d_none(p4d))
+ p4d_populate(&init_mm, p4dp, bm_pud);
+
+ pudp = pud_offset(p4dp, addr);
+
+#ifndef __PAGETABLE_PUD_FOLDED
+ pud_init(pudp);
+#endif
+ early_fixmap_init_pmd(pudp, addr, end);
+}
+
+/*
+ * The p*d_populate functions call virt_to_phys implicitly so they can't be used
+ * directly on kernel symbols (bm_p*d). This function is called too early to use
+ * lm_alias so __p*d_populate functions must be used to populate with the
+ * physical address from __pa_symbol.
+ */
+void __init early_fixmap_init(void)
+{
+ unsigned long addr = FIXADDR_START;
+ unsigned long end = FIXADDR_TOP;
+
+ pgd_t *pgdp = pgd_offset_k(addr);
+ p4d_t *p4dp = p4d_offset(pgdp, addr);
+
+ early_fixmap_init_pud(p4dp, addr, end);
+}
+
unsigned long empty_zero_page[PAGE_SIZE / sizeof(unsigned long)] __page_aligned_bss;
EXPORT_SYMBOL(empty_zero_page);
@@ -209,7 +312,7 @@ pte_t * __init populate_kernel_pte(unsigned long addr)
return pte_offset_kernel(pmd, addr);
}
-void __init __set_fixmap(enum fixed_addresses idx,
+void __set_fixmap(enum fixed_addresses idx,
phys_addr_t phys, pgprot_t flags)
{
unsigned long addr = __fix_to_virt(idx);
@@ -217,11 +320,7 @@ void __init __set_fixmap(enum fixed_addresses idx,
BUG_ON(idx <= FIX_HOLE || idx >= __end_of_fixed_addresses);
- ptep = populate_kernel_pte(addr);
- if (!pte_none(ptep_get(ptep))) {
- pte_ERROR(*ptep);
- return;
- }
+ ptep = fixmap_pte(addr);
if (pgprot_val(flags))
set_pte(ptep, pfn_pte(phys >> PAGE_SHIFT, flags));
--
2.25.1
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