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arm64: record boot mode when entering the kernel

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To be able to signal the availability of EL2 to other parts of
the kernel, record the boot mode.

Once booted, two predicates indicate if HYP mode is available,
and if not, whether this is due to a boot mode mismatch or not.

Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
This commit is contained in:
Marc Zyngier 2012-10-26 15:40:05 +01:00 committed by Catalin Marinas
parent dc637f1fda
commit f35a92053b
2 changed files with 73 additions and 3 deletions
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51
arch/arm64/include/asm/virt.h Normal file
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@ -0,0 +1,51 @@
/*
* Copyright (C) 2012 ARM Ltd.
* Author: Marc Zyngier <marc.zyngier@arm.com>
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#ifndef __ASM__VIRT_H
#define __ASM__VIRT_H
#define BOOT_CPU_MODE_EL2 (0x0e12b007)
#ifndef __ASSEMBLY__
/*
* __boot_cpu_mode records what mode CPUs were booted in.
* A correctly-implemented bootloader must start all CPUs in the same mode:
* In this case, both 32bit halves of __boot_cpu_mode will contain the
* same value (either 0 if booted in EL1, BOOT_CPU_MODE_EL2 if booted in EL2).
*
* Should the bootloader fail to do this, the two values will be different.
* This allows the kernel to flag an error when the secondaries have come up.
*/
extern u32 __boot_cpu_mode[2];
/* Reports the availability of HYP mode */
static inline bool is_hyp_mode_available(void)
{
return (__boot_cpu_mode[0] == BOOT_CPU_MODE_EL2 &&
__boot_cpu_mode[1] == BOOT_CPU_MODE_EL2);
}
/* Check if the bootloader has booted CPUs in different modes */
static inline bool is_hyp_mode_mismatched(void)
{
return __boot_cpu_mode[0] != __boot_cpu_mode[1];
}
#endif /* __ASSEMBLY__ */
#endif /* ! __ASM__VIRT_H */

25
arch/arm64/kernel/head.S
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@ -31,6 +31,7 @@
#include <asm/pgtable-hwdef.h>
#include <asm/pgtable.h>
#include <asm/page.h>
#include <asm/virt.h>
/*
* swapper_pg_dir is the virtual address of the initial page table. We place
@ -115,13 +116,13 @@
ENTRY(stext)
mov x21, x0 // x21=FDT
bl __calc_phys_offset // x24=PHYS_OFFSET, x28=PHYS_OFFSET-PAGE_OFFSET
bl el2_setup // Drop to EL1
mrs x22, midr_el1 // x22=cpuid
mov x0, x22
bl lookup_processor_type
mov x23, x0 // x23=current cpu_table
cbz x23, __error_p // invalid processor (x23=0)?
bl __calc_phys_offset // x24=PHYS_OFFSET, x28=PHYS_OFFSET-PAGE_OFFSET
bl __vet_fdt
bl __create_page_tables // x25=TTBR0, x26=TTBR1
/*
@ -147,11 +148,16 @@ ENTRY(el2_setup)
mrs x0, CurrentEL
cmp x0, #PSR_MODE_EL2t
ccmp x0, #PSR_MODE_EL2h, #0x4, ne
ldr x0, =__boot_cpu_mode // Compute __boot_cpu_mode
add x0, x0, x28
b.eq 1f
str wzr, [x0] // Remember we don't have EL2...
ret
/* Hyp configuration. */
1: mov x0, #(1 << 31) // 64-bit EL1
1: ldr w1, =BOOT_CPU_MODE_EL2
str w1, [x0, #4] // This CPU has EL2
mov x0, #(1 << 31) // 64-bit EL1
msr hcr_el2, x0
/* Generic timers. */
@ -187,6 +193,19 @@ ENTRY(el2_setup)
eret
ENDPROC(el2_setup)
/*
* We need to find out the CPU boot mode long after boot, so we need to
* store it in a writable variable.
*
* This is not in .bss, because we set it sufficiently early that the boot-time
* zeroing of .bss would clobber it.
*/
.pushsection .data
ENTRY(__boot_cpu_mode)
.long BOOT_CPU_MODE_EL2
.long 0
.popsection
.align 3
2: .quad .
.quad PAGE_OFFSET
@ -202,6 +221,7 @@ ENDPROC(el2_setup)
* cores are held until we're ready for them to initialise.
*/
ENTRY(secondary_holding_pen)
bl __calc_phys_offset // x24=phys offset
bl el2_setup // Drop to EL1
mrs x0, mpidr_el1
and x0, x0, #15 // CPU number
@ -227,7 +247,6 @@ ENTRY(secondary_startup)
mov x23, x0 // x23=current cpu_table
cbz x23, __error_p // invalid processor (x23=0)?
bl __calc_phys_offset // x24=phys offset
pgtbl x25, x26, x24 // x25=TTBR0, x26=TTBR1
ldr x12, [x23, #CPU_INFO_SETUP]
add x12, x12, x28 // __virt_to_phys