Unverified Commit 387181dc authored by Anup Patel's avatar Anup Patel Committed by Palmer Dabbelt
Browse files

RISC-V: Always compile mm/init.c with cmodel=medany and notrace 



The Linux RISC-V 32bit kernel is broken after we moved setup_vm() from
kernel/setup.c to mm/init.c because Linux RISC-V 32bit kernel by default
uses cmodel=medlow which results in a non-position-independent setup_vm().

This patch fixes Linux RISC-V 32bit kernel booting by:
1. Forcing cmodel=medany for mm/init.c
2. Moving remaing MM-related stuff va_pa_offset, pfn_base and
   empty_zero_page from kernel/setup.c to mm/init.c

Further, the setup_vm() cannot handle GCC instrumentation for FTRACE so
we disable it for mm/init.c by not using "-pg" compiler flag.

Fixes: 6f1e9e94 ("RISC-V: Move setup_vm() to mm/init.c")
Suggested-by: default avatarChristoph Hellwig <hch@lst.de>
Suggested-by: default avatarMike Rapoport <rppt@linux.ibm.com>
Signed-off-by: default avatarAnup Patel <anup.patel@wdc.com>
Reviewed-by: default avatarMike Rapoport <rppt@linux.ibm.com>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Signed-off-by: default avatarPalmer Dabbelt <palmer@sifive.com>
parent dbee9c9c

arch/riscv/kernel/Makefile

+0 −3
Original line number Diff line number Diff line
@@ -4,7 +4,6 @@ 


ifdef CONFIG_FTRACE

CFLAGS_REMOVE_ftrace.o = -pg

CFLAGS_REMOVE_setup.o = -pg

endif



extra-y += head.o
@@ -29,8 +28,6 @@ obj-y += vdso.o 
obj-y	+= cacheinfo.o

obj-y	+= vdso/



CFLAGS_setup.o := -mcmodel=medany



obj-$(CONFIG_FPU)		+= fpu.o

obj-$(CONFIG_SMP)		+= smpboot.o

obj-$(CONFIG_SMP)		+= smp.o

arch/riscv/kernel/setup.c

+0 −8
Original line number Diff line number Diff line
@@ -48,14 +48,6 @@ struct screen_info screen_info = { 
};

#endif



unsigned long va_pa_offset;

EXPORT_SYMBOL(va_pa_offset);

unsigned long pfn_base;

EXPORT_SYMBOL(pfn_base);



unsigned long empty_zero_page[PAGE_SIZE / sizeof(unsigned long)] __page_aligned_bss;

EXPORT_SYMBOL(empty_zero_page);



/* The lucky hart to first increment this variable will boot the other cores */

atomic_t hart_lottery;

unsigned long boot_cpu_hartid;

arch/riscv/mm/Makefile

+6 −0
Original line number Diff line number Diff line 


CFLAGS_init.o := -mcmodel=medany

ifdef CONFIG_FTRACE

CFLAGS_REMOVE_init.o = -pg

endif



obj-y += init.o

obj-y += fault.o

obj-y += extable.o

arch/riscv/mm/init.c

+28 −0
Original line number Diff line number Diff line
@@ -25,6 +25,10 @@ 
#include <asm/pgtable.h>

#include <asm/io.h>



unsigned long empty_zero_page[PAGE_SIZE / sizeof(unsigned long)]

							__page_aligned_bss;

EXPORT_SYMBOL(empty_zero_page);



static void __init zone_sizes_init(void)

{

	unsigned long max_zone_pfns[MAX_NR_ZONES] = { 0, };
@@ -143,6 +147,11 @@ void __init setup_bootmem(void) 
	}

}



unsigned long va_pa_offset;

EXPORT_SYMBOL(va_pa_offset);

unsigned long pfn_base;

EXPORT_SYMBOL(pfn_base);



pgd_t swapper_pg_dir[PTRS_PER_PGD] __page_aligned_bss;

pgd_t trampoline_pg_dir[PTRS_PER_PGD] __initdata __aligned(PAGE_SIZE);
@@ -172,6 +181,25 @@ void __set_fixmap(enum fixed_addresses idx, phys_addr_t phys, pgprot_t prot) 
	}

}



/*

 * setup_vm() is called from head.S with MMU-off.

 *

 * Following requirements should be honoured for setup_vm() to work

 * correctly:

 * 1) It should use PC-relative addressing for accessing kernel symbols.

 *    To achieve this we always use GCC cmodel=medany.

 * 2) The compiler instrumentation for FTRACE will not work for setup_vm()

 *    so disable compiler instrumentation when FTRACE is enabled.

 *

 * Currently, the above requirements are honoured by using custom CFLAGS

 * for init.o in mm/Makefile.

 */



#ifndef __riscv_cmodel_medany

#error "setup_vm() is called from head.S before relocate so it should "

	"not use absolute addressing."

#endif



asmlinkage void __init setup_vm(void)

{

	extern char _start;

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