Re: [PATCH 6/7] KVM: arm64: re-factor hyp.S debug register code

From: Alex BennÃe
Date: Mon Dec 01 2014 - 06:52:44 EST



Christoffer Dall <christoffer.dall@xxxxxxxxxx> writes:

> On Tue, Nov 25, 2014 at 04:10:04PM +0000, Alex BennÃe wrote:
>> This is a pre-cursor to sharing the code with the guest debug support.
>> This replaces the big macro that fishes data out of a fixed location
>> with a more general helper macro to restore a set of debug registers. It
>> uses macro substitution so it can be re-used for debug control and value
>> registers. It does however rely on the debug registers being 64 bit
>> aligned (as they happen to be in the hyp ABI).
>
> can you enforce that somewhere?

There is a comment in kvm_asm.h:

/*
* 0 is reserved as an invalid value.
* Order *must* be kept in sync with the hyp switch code.
*/

But I'm not sure how to enforce it in assembly. Is there a #pragma or
something I can use?

>
>>
>> Signed-off-by: Alex BennÃe <alex.bennee@xxxxxxxxxx>
>>
>> diff --git a/arch/arm64/kvm/hyp.S b/arch/arm64/kvm/hyp.S
>> index c0bc218..b38ce3d 100644
>> --- a/arch/arm64/kvm/hyp.S
>> +++ b/arch/arm64/kvm/hyp.S
>> @@ -490,65 +490,12 @@
>> msr mdscr_el1, x25
>> .endm
>>
>> -.macro restore_debug
>> - // x2: base address for cpu context
>> - // x3: tmp register
>> -
>> - mrs x26, id_aa64dfr0_el1
>> - ubfx x24, x26, #12, #4 // Extract BRPs
>> - ubfx x25, x26, #20, #4 // Extract WRPs
>> - mov w26, #15
>> - sub w24, w26, w24 // How many BPs to skip
>> - sub w25, w26, w25 // How many WPs to skip
>> -
>> - add x3, x2, #CPU_SYSREG_OFFSET(DBGBCR0_EL1)
>> -
>> - adr x26, 1f
>> - add x26, x26, x24, lsl #2
>> - br x26
>> -1:
>> - ldr x20, [x3, #(15 * 8)]
>> - ldr x19, [x3, #(14 * 8)]
>> - ldr x18, [x3, #(13 * 8)]
>> - ldr x17, [x3, #(12 * 8)]
>> - ldr x16, [x3, #(11 * 8)]
>> - ldr x15, [x3, #(10 * 8)]
>> - ldr x14, [x3, #(9 * 8)]
>> - ldr x13, [x3, #(8 * 8)]
>> - ldr x12, [x3, #(7 * 8)]
>> - ldr x11, [x3, #(6 * 8)]
>> - ldr x10, [x3, #(5 * 8)]
>> - ldr x9, [x3, #(4 * 8)]
>> - ldr x8, [x3, #(3 * 8)]
>> - ldr x7, [x3, #(2 * 8)]
>> - ldr x6, [x3, #(1 * 8)]
>> - ldr x5, [x3, #(0 * 8)]
>> -
>> +.macro setup_debug_registers type
>> + // x3: pointer to register set
>> + // x4: number of registers to copy
>> + // x5..x20/x26 trashed
>
> does this mean x5 through x20, and x26, get trashed or that potentially
> x5 thgough x26 get trashed? I'm assuming the first, so replace the
> slash with 'and' would be more clear.
>
>> adr x26, 1f
>> - add x26, x26, x24, lsl #2
>> - br x26
>> -1:
>> - msr dbgbcr15_el1, x20
>> - msr dbgbcr14_el1, x19
>> - msr dbgbcr13_el1, x18
>> - msr dbgbcr12_el1, x17
>> - msr dbgbcr11_el1, x16
>> - msr dbgbcr10_el1, x15
>> - msr dbgbcr9_el1, x14
>> - msr dbgbcr8_el1, x13
>> - msr dbgbcr7_el1, x12
>> - msr dbgbcr6_el1, x11
>> - msr dbgbcr5_el1, x10
>> - msr dbgbcr4_el1, x9
>> - msr dbgbcr3_el1, x8
>> - msr dbgbcr2_el1, x7
>> - msr dbgbcr1_el1, x6
>> - msr dbgbcr0_el1, x5
>> -
>> - add x3, x2, #CPU_SYSREG_OFFSET(DBGBVR0_EL1)
>> -
>> - adr x26, 1f
>> - add x26, x26, x24, lsl #2
>> + add x26, x26, x4, lsl #2
>> br x26
>> 1:
>> ldr x20, [x3, #(15 * 8)]
>> @@ -569,116 +516,25 @@
>> ldr x5, [x3, #(0 * 8)]
>>
>> adr x26, 1f
>> - add x26, x26, x24, lsl #2
>> - br x26
>> -1:
>> - msr dbgbvr15_el1, x20
>> - msr dbgbvr14_el1, x19
>> - msr dbgbvr13_el1, x18
>> - msr dbgbvr12_el1, x17
>> - msr dbgbvr11_el1, x16
>> - msr dbgbvr10_el1, x15
>> - msr dbgbvr9_el1, x14
>> - msr dbgbvr8_el1, x13
>> - msr dbgbvr7_el1, x12
>> - msr dbgbvr6_el1, x11
>> - msr dbgbvr5_el1, x10
>> - msr dbgbvr4_el1, x9
>> - msr dbgbvr3_el1, x8
>> - msr dbgbvr2_el1, x7
>> - msr dbgbvr1_el1, x6
>> - msr dbgbvr0_el1, x5
>> -
>> - add x3, x2, #CPU_SYSREG_OFFSET(DBGWCR0_EL1)
>> -
>> - adr x26, 1f
>> - add x26, x26, x25, lsl #2
>> + add x26, x26, x4, lsl #2
>> br x26
>> 1:
>> - ldr x20, [x3, #(15 * 8)]
>> - ldr x19, [x3, #(14 * 8)]
>> - ldr x18, [x3, #(13 * 8)]
>> - ldr x17, [x3, #(12 * 8)]
>> - ldr x16, [x3, #(11 * 8)]
>> - ldr x15, [x3, #(10 * 8)]
>> - ldr x14, [x3, #(9 * 8)]
>> - ldr x13, [x3, #(8 * 8)]
>> - ldr x12, [x3, #(7 * 8)]
>> - ldr x11, [x3, #(6 * 8)]
>> - ldr x10, [x3, #(5 * 8)]
>> - ldr x9, [x3, #(4 * 8)]
>> - ldr x8, [x3, #(3 * 8)]
>> - ldr x7, [x3, #(2 * 8)]
>> - ldr x6, [x3, #(1 * 8)]
>> - ldr x5, [x3, #(0 * 8)]
>> -
>> - adr x26, 1f
>> - add x26, x26, x25, lsl #2
>> - br x26
>> -1:
>> - msr dbgwcr15_el1, x20
>> - msr dbgwcr14_el1, x19
>> - msr dbgwcr13_el1, x18
>> - msr dbgwcr12_el1, x17
>> - msr dbgwcr11_el1, x16
>> - msr dbgwcr10_el1, x15
>> - msr dbgwcr9_el1, x14
>> - msr dbgwcr8_el1, x13
>> - msr dbgwcr7_el1, x12
>> - msr dbgwcr6_el1, x11
>> - msr dbgwcr5_el1, x10
>> - msr dbgwcr4_el1, x9
>> - msr dbgwcr3_el1, x8
>> - msr dbgwcr2_el1, x7
>> - msr dbgwcr1_el1, x6
>> - msr dbgwcr0_el1, x5
>> -
>> - add x3, x2, #CPU_SYSREG_OFFSET(DBGWVR0_EL1)
>> -
>> - adr x26, 1f
>> - add x26, x26, x25, lsl #2
>> - br x26
>> -1:
>> - ldr x20, [x3, #(15 * 8)]
>> - ldr x19, [x3, #(14 * 8)]
>> - ldr x18, [x3, #(13 * 8)]
>> - ldr x17, [x3, #(12 * 8)]
>> - ldr x16, [x3, #(11 * 8)]
>> - ldr x15, [x3, #(10 * 8)]
>> - ldr x14, [x3, #(9 * 8)]
>> - ldr x13, [x3, #(8 * 8)]
>> - ldr x12, [x3, #(7 * 8)]
>> - ldr x11, [x3, #(6 * 8)]
>> - ldr x10, [x3, #(5 * 8)]
>> - ldr x9, [x3, #(4 * 8)]
>> - ldr x8, [x3, #(3 * 8)]
>> - ldr x7, [x3, #(2 * 8)]
>> - ldr x6, [x3, #(1 * 8)]
>> - ldr x5, [x3, #(0 * 8)]
>> -
>> - adr x26, 1f
>> - add x26, x26, x25, lsl #2
>> - br x26
>> -1:
>> - msr dbgwvr15_el1, x20
>> - msr dbgwvr14_el1, x19
>> - msr dbgwvr13_el1, x18
>> - msr dbgwvr12_el1, x17
>> - msr dbgwvr11_el1, x16
>> - msr dbgwvr10_el1, x15
>> - msr dbgwvr9_el1, x14
>> - msr dbgwvr8_el1, x13
>> - msr dbgwvr7_el1, x12
>> - msr dbgwvr6_el1, x11
>> - msr dbgwvr5_el1, x10
>> - msr dbgwvr4_el1, x9
>> - msr dbgwvr3_el1, x8
>> - msr dbgwvr2_el1, x7
>> - msr dbgwvr1_el1, x6
>> - msr dbgwvr0_el1, x5
>> -
>> - ldr x21, [x2, #CPU_SYSREG_OFFSET(MDCCINT_EL1)]
>> - msr mdccint_el1, x21
>> + msr \type\()15_el1, x20
>> + msr \type\()14_el1, x19
>> + msr \type\()13_el1, x18
>> + msr \type\()12_el1, x17
>> + msr \type\()11_el1, x16
>> + msr \type\()10_el1, x15
>> + msr \type\()9_el1, x14
>> + msr \type\()8_el1, x13
>> + msr \type\()7_el1, x12
>> + msr \type\()6_el1, x11
>> + msr \type\()5_el1, x10
>> + msr \type\()4_el1, x9
>> + msr \type\()3_el1, x8
>> + msr \type\()2_el1, x7
>> + msr \type\()1_el1, x6
>> + msr \type\()0_el1, x5
>> .endm
>>
>> .macro skip_32bit_state tmp, target
>> @@ -929,8 +785,34 @@ __save_debug:
>> save_debug
>> ret
>>
>> +/* Restore saved guest debug state */
>> __restore_debug:
>> - restore_debug
>> + // x2: base address for cpu context
>> + // x3: ptr to guest registers passed to setup_debug_registers
>> + // x5..x20/x26: trashed
>> +
>> + mrs x26, id_aa64dfr0_el1
>> + ubfx x24, x26, #12, #4 // Extract BRPs
>> + ubfx x25, x26, #20, #4 // Extract WRPs
>> + mov w26, #15
>> + sub w24, w26, w24 // How many BPs to skip
>> + sub w25, w26, w25 // How many WPs to skip
>> +
>> + mov x4, x24
>> + add x3, x2, #CPU_SYSREG_OFFSET(DBGBCR0_EL1)
>> + setup_debug_registers dbgbcr
>> + add x3, x2, #CPU_SYSREG_OFFSET(DBGBVR0_EL1)
>> + setup_debug_registers dbgbvr
>> +
>> + mov x4, x25
>> + add x3, x2, #CPU_SYSREG_OFFSET(DBGWCR0_EL1)
>> + setup_debug_registers dbgwcr
>> + add x3, x2, #CPU_SYSREG_OFFSET(DBGWVR0_EL1)
>> + setup_debug_registers dbgwvr
>> +
>> + ldr x21, [x2, #CPU_SYSREG_OFFSET(MDCCINT_EL1)]
>> + msr mdccint_el1, x21
>> +
>> ret
>>
>> __save_fpsimd:
>> --
>> 2.1.3
>>

--
Alex BennÃe
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