riscv: Remove CONFIG_PAGE_OFFSET

The current definition of CONFIG_PAGE_OFFSET is problematic for a couple
of reasons:
 1) The value is misleading for normal 64-bit kernels, where it is
    overridden at runtime if Sv48 or Sv39 is chosen. This is especially
    the case for XIP kernels, which always use Sv39.
 2) The option is not user-visible, but for NOMMU kernels it must be a
    valid RAM address, and for !RELOCATABLE it must additionally be the
    exact address where the kernel is loaded.

Fix both of these by removing the option.
 1) For MMU kernels, drop the indirection through Kconfig. Additionally,
    for XIP, drop the indirection through kernel_map.
 2) For NOMMU kernels, use the user-visible physical RAM base if
    provided. Otherwise, force the kernel to be relocatable.

Signed-off-by: Samuel Holland <samuel.holland@sifive.com>
Reviewed-by: Jesse Taube <mr.bossman075@gmail.com>
Link: https://lore.kernel.org/r/20241026171441.3047904-7-samuel.holland@sifive.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>

diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index 7d3d457045eec597b263b0f16c508f14fba4c94f..551b9a9b243fda6c3f2d863103c7197ed3be703e 100644 (file)
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -201,6 +201,7 @@ config RISCV
        select PCI_DOMAINS_GENERIC if PCI
        select PCI_ECAM if (ACPI && PCI)
        select PCI_MSI if PCI
+       select RELOCATABLE if !MMU && !PHYS_RAM_BASE_FIXED
        select RISCV_ALTERNATIVE if !XIP_KERNEL
        select RISCV_APLIC
        select RISCV_IMSIC
@@ -288,13 +289,6 @@ config MMU
          Select if you want MMU-based virtualised addressing space
          support by paged memory management. If unsure, say 'Y'.
 
-config PAGE_OFFSET
-       hex
-       default 0x80000000 if !MMU && RISCV_M_MODE
-       default 0x80200000 if !MMU
-       default 0xc0000000 if 32BIT
-       default 0xff60000000000000 if 64BIT
-
 config KASAN_SHADOW_OFFSET
        hex
        depends on KASAN_GENERIC

diff --git a/arch/riscv/include/asm/page.h b/arch/riscv/include/asm/page.h
index 6409fd78ae6fa59b4dbfa5151248aee8ae3f424f..572a141ddecdb19f587415dc61f8343cfc3d3a29 100644 (file)
--- a/arch/riscv/include/asm/page.h
+++ b/arch/riscv/include/asm/page.h
@@ -26,15 +26,16 @@
  */
 #ifdef CONFIG_MMU
 #ifdef CONFIG_64BIT
-#define PAGE_OFFSET            kernel_map.page_offset
-/*
- * By default, CONFIG_PAGE_OFFSET value corresponds to SV57 address space so
- * define the PAGE_OFFSET value for SV48 and SV39.
- */
+#define PAGE_OFFSET_L5         _AC(0xff60000000000000, UL)
 #define PAGE_OFFSET_L4         _AC(0xffffaf8000000000, UL)
 #define PAGE_OFFSET_L3         _AC(0xffffffd600000000, UL)
+#ifdef CONFIG_XIP_KERNEL
+#define PAGE_OFFSET            PAGE_OFFSET_L3
 #else
-#define PAGE_OFFSET            _AC(CONFIG_PAGE_OFFSET, UL)
+#define PAGE_OFFSET            kernel_map.page_offset
+#endif /* CONFIG_XIP_KERNEL */
+#else
+#define PAGE_OFFSET            _AC(0xc0000000, UL)
 #endif /* CONFIG_64BIT */
 #else
 #define PAGE_OFFSET            ((unsigned long)phys_ram_base)
@@ -98,7 +99,6 @@ typedef struct page *pgtable_t;
 #define ARCH_PFN_OFFSET                (PFN_DOWN((unsigned long)phys_ram_base))
 
 struct kernel_mapping {
-       unsigned long page_offset;
        unsigned long virt_addr;
        unsigned long virt_offset;
        uintptr_t phys_addr;
@@ -112,6 +112,7 @@ struct kernel_mapping {
        uintptr_t xiprom;
        uintptr_t xiprom_sz;
 #else
+       unsigned long page_offset;
        unsigned long va_kernel_pa_offset;
 #endif
 };

diff --git a/arch/riscv/include/asm/pgtable.h b/arch/riscv/include/asm/pgtable.h
index babd951222db1fc5723443af75d78edfd7992a31..ddebdfb4519ad7d4a158e915bc6e1632cb18e331 100644 (file)
--- a/arch/riscv/include/asm/pgtable.h
+++ b/arch/riscv/include/asm/pgtable.h
@@ -15,7 +15,7 @@
 #ifdef CONFIG_RELOCATABLE
 #define KERNEL_LINK_ADDR       UL(0)
 #else
-#define KERNEL_LINK_ADDR       _AC(CONFIG_PAGE_OFFSET, UL)
+#define KERNEL_LINK_ADDR       _AC(CONFIG_PHYS_RAM_BASE, UL)
 #endif
 #define KERN_VIRT_SIZE         (UL(-1))
 #else

diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
index d1494d48a70d6028f36615ce8f5adf97de2f3716..37af6513a50f56996b7290cad5346f7328415437 100644 (file)
--- a/arch/riscv/mm/init.c
+++ b/arch/riscv/mm/init.c
@@ -859,6 +859,8 @@ static __init void set_satp_mode(uintptr_t dtb_pa)
        uintptr_t set_satp_mode_pmd = ((unsigned long)set_satp_mode) & PMD_MASK;
        u64 satp_mode_cmdline = __pi_set_satp_mode_from_cmdline(dtb_pa);
 
+       kernel_map.page_offset = PAGE_OFFSET_L5;
+
        if (satp_mode_cmdline == SATP_MODE_57) {
                disable_pgtable_l5();
        } else if (satp_mode_cmdline == SATP_MODE_48) {
@@ -1106,11 +1108,6 @@ asmlinkage void __init setup_vm(uintptr_t dtb_pa)
        kernel_map.virt_addr = KERNEL_LINK_ADDR + kernel_map.virt_offset;
 
 #ifdef CONFIG_XIP_KERNEL
-#ifdef CONFIG_64BIT
-       kernel_map.page_offset = PAGE_OFFSET_L3;
-#else
-       kernel_map.page_offset = _AC(CONFIG_PAGE_OFFSET, UL);
-#endif
        kernel_map.xiprom = (uintptr_t)CONFIG_XIP_PHYS_ADDR;
        kernel_map.xiprom_sz = (uintptr_t)(&_exiprom) - (uintptr_t)(&_xiprom);
 
@@ -1125,7 +1122,6 @@ asmlinkage void __init setup_vm(uintptr_t dtb_pa)
        kernel_map.va_kernel_xip_data_pa_offset = kernel_map.virt_addr - kernel_map.phys_addr
                                                + (uintptr_t)&_sdata - (uintptr_t)&_start;
 #else
-       kernel_map.page_offset = _AC(CONFIG_PAGE_OFFSET, UL);
        kernel_map.phys_addr = (uintptr_t)(&_start);
        kernel_map.size = (uintptr_t)(&_end) - kernel_map.phys_addr;
        kernel_map.va_kernel_pa_offset = kernel_map.virt_addr - kernel_map.phys_addr;