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arm64: kernel: use ordinary return/argument register for el2_setup()

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The function el2_setup() passes its return value in register w20, and
in the two cases where the caller actually cares about this return value,
it is passed into set_cpu_boot_mode_flag() [almost] directly, which
expects its input in w20 as well.

So there is no reason to use a 'special' callee saved register here, but
we can simply follow the PCS for return value and first argument,
respectively.

Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
This commit is contained in:
Ard Biesheuvel 2016-08-31 12:05:12 +01:00 committed by Will Deacon
parent b5fe242972
commit 23c8a500c2
1 changed files with 7 additions and 7 deletions
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14
arch/arm64/kernel/head.S
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@ -210,7 +210,7 @@ efi_header_end:
ENTRY(stext)
bl preserve_boot_args
bl el2_setup // Drop to EL1, w20=cpu_boot_mode
bl el2_setup // Drop to EL1, w0=cpu_boot_mode
adrp x24, __PHYS_OFFSET
and x23, x24, MIN_KIMG_ALIGN - 1 // KASLR offset, defaults to 0
bl set_cpu_boot_mode_flag
@ -488,7 +488,7 @@ CPU_LE( bic x0, x0, #(1 << 25) ) // Clear the EE bit for EL2
CPU_BE( orr x0, x0, #(3 << 24) ) // Set the EE and E0E bits for EL1
CPU_LE( bic x0, x0, #(3 << 24) ) // Clear the EE and E0E bits for EL1
msr sctlr_el1, x0
mov w20, #BOOT_CPU_MODE_EL1 // This cpu booted in EL1
mov w0, #BOOT_CPU_MODE_EL1 // This cpu booted in EL1
isb
ret
@ -584,7 +584,7 @@ CPU_LE( movk x0, #0x30d0, lsl #16 ) // Clear EE and E0E on LE systems
cbz x2, install_el2_stub
mov w20, #BOOT_CPU_MODE_EL2 // This CPU booted in EL2
mov w0, #BOOT_CPU_MODE_EL2 // This CPU booted in EL2
isb
ret
@ -599,7 +599,7 @@ install_el2_stub:
PSR_MODE_EL1h)
msr spsr_el2, x0
msr elr_el2, lr
mov w20, #BOOT_CPU_MODE_EL2 // This CPU booted in EL2
mov w0, #BOOT_CPU_MODE_EL2 // This CPU booted in EL2
eret
ENDPROC(el2_setup)
@ -609,10 +609,10 @@ ENDPROC(el2_setup)
*/
set_cpu_boot_mode_flag:
adr_l x1, __boot_cpu_mode
cmp w20, #BOOT_CPU_MODE_EL2
cmp w0, #BOOT_CPU_MODE_EL2
b.ne 1f
add x1, x1, #4
1: str w20, [x1] // This CPU has booted in EL1
1: str w0, [x1] // This CPU has booted in EL1
dmb sy
dc ivac, x1 // Invalidate potentially stale cache line
ret
@ -649,7 +649,7 @@ ENTRY(__early_cpu_boot_status)
* cores are held until we're ready for them to initialise.
*/
ENTRY(secondary_holding_pen)
bl el2_setup // Drop to EL1, w20=cpu_boot_mode
bl el2_setup // Drop to EL1, w0=cpu_boot_mode
bl set_cpu_boot_mode_flag
mrs x0, mpidr_el1
mov_q x1, MPIDR_HWID_BITMASK