Unverified Commit f633de4a authored by Palmer Dabbelt's avatar Palmer Dabbelt
Browse files

Merge patch series "riscv: Relocatable NOMMU kernels" 

Samuel Holland <samuel.holland@sifive.com> says:

Currently, RISC-V NOMMU kernels are linked at CONFIG_PAGE_OFFSET, and
since they are not relocatable, must be loaded at this address as well.
CONFIG_PAGE_OFFSET is not a user-visible Kconfig option, so its value is
not obvious, and users must patch the kernel source if they want to load
it at a different address.

Make NOMMU kernels more portable by making them relocatable by default.
This allows a single kernel binary to work when loaded at any address.

* b4-shazam-merge:
  riscv: Remove CONFIG_PAGE_OFFSET
  riscv: Support CONFIG_RELOCATABLE on riscv32
  asm-generic: Always define Elf_Rel and Elf_Rela
  riscv: Support CONFIG_RELOCATABLE on NOMMU
  riscv: Allow NOMMU kernels to access all of RAM
  riscv: Remove duplicate CONFIG_PAGE_OFFSET definition

Link: https://lore.kernel.org/r/20241026171441.3047904-1-samuel.holland@sifive.com


Signed-off-by: default avatarPalmer Dabbelt <palmer@rivosinc.com>
parents df023513 e1cf2d00

arch/riscv/Kconfig

+2 −8
Original line number Diff line number Diff line
@@ -202,6 +202,7 @@ 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
@@ -289,13 +290,6 @@ 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
@@ -1100,7 +1094,7 @@ config PARAVIRT_TIME_ACCOUNTING 


config RELOCATABLE

	bool "Build a relocatable kernel"

	depends on MMU && 64BIT && !XIP_KERNEL

	depends on !XIP_KERNEL

	select MODULE_SECTIONS if MODULES

	help

          This builds a kernel as a Position Independent Executable (PIE),

arch/riscv/Makefile

+0 −1
Original line number Diff line number Diff line
@@ -98,7 +98,6 @@ KBUILD_AFLAGS += -march=$(riscv-march-y) 
CC_FLAGS_FPU  := -march=$(shell echo $(riscv-march-y) | sed -E 's/(rv32ima|rv64ima)([^v_]*)v?/\1\2/')



KBUILD_CFLAGS += -mno-save-restore

KBUILD_CFLAGS += -DCONFIG_PAGE_OFFSET=$(CONFIG_PAGE_OFFSET)



ifeq ($(CONFIG_CMODEL_MEDLOW),y)

	KBUILD_CFLAGS += -mcmodel=medlow

arch/riscv/errata/Makefile

+5 −1
Original line number Diff line number Diff line 
ifdef CONFIG_RELOCATABLE

KBUILD_CFLAGS += -fno-pie

# We can't use PIC/PIE when handling early-boot errata parsing, as the kernel

# doesn't have a GOT setup at that point.  So instead just use medany: it's

# usually position-independent, so it should be good enough for the errata

# handling.

KBUILD_CFLAGS += -fno-pie -mcmodel=medany

endif



ifdef CONFIG_RISCV_ALTERNATIVE_EARLY

arch/riscv/include/asm/page.h

+12 −15
Original line number Diff line number Diff line
@@ -24,21 +24,22 @@ 
 * When not using MMU this corresponds to the first free page in

 * physical memory (aligned on a page boundary).

 */

#ifdef CONFIG_64BIT

#ifdef CONFIG_MMU

#define PAGE_OFFSET		kernel_map.page_offset

#else

#define PAGE_OFFSET		_AC(CONFIG_PAGE_OFFSET, UL)

#endif

/*

 * By default, CONFIG_PAGE_OFFSET value corresponds to SV57 address space so

 * define the PAGE_OFFSET value for SV48 and SV39.

 */

#ifdef CONFIG_64BIT

#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)

#endif /* CONFIG_MMU */



#ifndef __ASSEMBLY__
@@ -95,14 +96,9 @@ typedef struct page *pgtable_t; 
#define MIN_MEMBLOCK_ADDR      0

#endif



#ifdef CONFIG_MMU

#define ARCH_PFN_OFFSET		(PFN_DOWN((unsigned long)phys_ram_base))

#else

#define ARCH_PFN_OFFSET		(PAGE_OFFSET >> PAGE_SHIFT)

#endif /* CONFIG_MMU */



struct kernel_mapping {

	unsigned long page_offset;

	unsigned long virt_addr;

	unsigned long virt_offset;

	uintptr_t phys_addr;
@@ -116,6 +112,7 @@ struct kernel_mapping { 
	uintptr_t xiprom;

	uintptr_t xiprom_sz;

#else

	unsigned long page_offset;

	unsigned long va_kernel_pa_offset;

#endif

};

arch/riscv/include/asm/pgtable.h

+5 −1
Original line number Diff line number Diff line
@@ -12,7 +12,11 @@ 
#include <asm/pgtable-bits.h>



#ifndef CONFIG_MMU

#define KERNEL_LINK_ADDR	PAGE_OFFSET

#ifdef CONFIG_RELOCATABLE

#define KERNEL_LINK_ADDR	UL(0)

#else

#define KERNEL_LINK_ADDR	_AC(CONFIG_PHYS_RAM_BASE, UL)

#endif

#define KERN_VIRT_SIZE		(UL(-1))

#else