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

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
......@@ -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
......
......@@ -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;
......
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
......
......@@ -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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