[BOOT-WRAPPER 00/11] Cleanup initialization

[BOOT-WRAPPER 00/11] Cleanup initialization

[Mark Rutland]

These patches cleanup the boot-wrapper initialization logic to make it
more consistent and easier to extend in C code in future. The big
changes are:

* The kernel is always entered via an exception return. This allows us
  to initialize PSTATE consistently, and will allow us to adjust the
  SPSR dynamically in C code in future if necessary.

* Regardless of the entered exception level, CPU state is initialized
  under cpu_init_arch(), allowing for logic to be shared regardless of
  which exception level was entered.

* CPUs are initialized sequentially, which allows better for better
  logging within the boot-wrapper.

Mark.

Mark Rutland (11):
  Always enter AArch32 kernels in ARM mode
  aarch64: Remove redundant EL1 entry logic
  aarch64: Implement cpu_init_arch()
  aarch64: Always enter kernel via exception return
  aarch32: Refactor inital entry
  aarch32: Implement cpu_init_arch()
  aarch32: Always enter kernel via exception return
  Unify assembly setup paths
  Simplify spin logic
  Add printing functions
  Boot CPUs sequentially

 arch/aarch32/boot.S                          | 95 ++++++++++----------
 arch/aarch32/include/asm/{gic-v3.h => gic.h} |  2 +-
 arch/aarch32/init.c                          | 30 +++++--
 arch/aarch64/boot.S                          | 66 ++++----------
 arch/aarch64/include/asm/{gic-v3.h => gic.h} |  2 +-
 arch/aarch64/init.c                          | 30 +++++--
 arch/aarch64/spin.S                          | 14 +--
 common/boot.c                                | 20 ++---
 common/gic-v3.c                              |  2 +-
 common/gic.c                                 |  2 +-
 common/init.c                                | 50 +++++++++--
 common/platform.c                            | 35 ++++++++
 common/psci.c                                | 16 +---
 include/boot.h                               |  8 +-
 include/gic.h                                | 16 ++++
 include/platform.h                           |  4 +
 16 files changed, 221 insertions(+), 171 deletions(-)
 rename arch/aarch32/include/asm/{gic-v3.h => gic.h} (91%)
 rename arch/aarch64/include/asm/{gic-v3.h => gic.h} (92%)
 create mode 100644 include/gic.h

-- 
2.30.2

[BOOT-WRAPPER 01/11] Always enter AArch32 kernels in ARM mode

[Mark Rutland]

Currnetly we try to support entering AArch32 kernels, but this is
unnecessary, and the code is never exercised.

Per Linux's Documentation/arch/arm/booting.txt, AArch32 kernels
supported by the AArch64 boot-wrapper should always be entered in ARM
mode:

| The boot loader is expected to call the kernel image by jumping
| directly to the first instruction of the kernel image.
|
| On CPUs supporting the ARM instruction set, the entry must be
| made in ARM state, even for a Thumb-2 kernel.
|
| On CPUs supporting only the Thumb instruction set such as
| Cortex-M class CPUs, the entry must be made in Thumb state.

Additionally, the kernel__start symbol that we use as the kernel
entrypoint is always PHYS_OFFSET + KERNEL_OFFSET, which doesn't take
into account any ARM/Thumb distinction in the AArch32 kernel image, and
hence we'll never try to set the Thumb bit in the SPSR.

Remove the redundant code.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Akos Denke <akos.denke@arm.com>
Cc: Andre Przywara <andre.przywara@arm.com>
Cc: Luca Fancellu <luca.fancellu@arm.com>
Cc: Marc Zyngier <maz@kernel.org>
---
 arch/aarch32/boot.S | 4 ----
 arch/aarch64/boot.S | 7 -------
 2 files changed, 11 deletions(-)

diff --git a/arch/aarch32/boot.S b/arch/aarch32/boot.S
index 4d16c9c..5c2a183 100644
--- a/arch/aarch32/boot.S
+++ b/arch/aarch32/boot.S
@@ -105,10 +105,6 @@ ASM_FUNC(jump_kernel)
 	bxeq	lr				@ no EL3
 
 	ldr	r4, =SPSR_KERNEL
-	/* Return in thumb2 mode when bit 0 of address is 1 */
-	tst	lr, #1
-	orrne	r4, #PSR_T
-
 	msr	spsr_cxf, r4
 	movs	pc, lr
 
diff --git a/arch/aarch64/boot.S b/arch/aarch64/boot.S
index da5fa65..b889137 100644
--- a/arch/aarch64/boot.S
+++ b/arch/aarch64/boot.S
@@ -136,13 +136,6 @@ ASM_FUNC(jump_kernel)
 	br	x19			// No EL3
 
 1:	mov	x4, #SPSR_KERNEL
-
-	/*
-	 * If bit 0 of the kernel address is set, we're entering in AArch32
-	 * thumb mode. Set SPSR.T accordingly.
-	 */
-	bfi	x4, x19, #5, #1
-
 	msr	elr_el3, x19
 	msr	spsr_el3, x4
 	eret
-- 
2.30.2

Re: [BOOT-WRAPPER 01/11] Always enter AArch32 kernels in ARM mode

[Andre Przywara]

On Mon, 29 Jul 2024 17:14:51 +0100
Mark Rutland <mark.rutland@arm.com> wrote:

> Currnetly we try to support entering AArch32 kernels, but this is

I think you are missing "in Thumb mode" here? The read is a bit confusing
otherwise.

> unnecessary, and the code is never exercised.
> 
> Per Linux's Documentation/arch/arm/booting.txt, AArch32 kernels
> supported by the AArch64 boot-wrapper should always be entered in ARM
> mode:
> 
> | The boot loader is expected to call the kernel image by jumping
> | directly to the first instruction of the kernel image.
> |
> | On CPUs supporting the ARM instruction set, the entry must be
> | made in ARM state, even for a Thumb-2 kernel.
> |
> | On CPUs supporting only the Thumb instruction set such as
> | Cortex-M class CPUs, the entry must be made in Thumb state.
> 
> Additionally, the kernel__start symbol that we use as the kernel
> entrypoint is always PHYS_OFFSET + KERNEL_OFFSET, which doesn't take
> into account any ARM/Thumb distinction in the AArch32 kernel image, and
> hence we'll never try to set the Thumb bit in the SPSR.

Is that true? I see the first_spin code path for CPU 0 using those values,
which indeed never have bit 0 set, but the address could come from *mbox
as well, given by the live kernel in the PSCI code path, and we don't have
any control over that.
Or do I miss anything here?

I think the patch is still valid, but we might need to relax the commit
message here a bit?

Cheers,
Andre

> 
> Remove the redundant code.
> 
> Signed-off-by: Mark Rutland <mark.rutland@arm.com>
> Cc: Akos Denke <akos.denke@arm.com>
> Cc: Andre Przywara <andre.przywara@arm.com>
> Cc: Luca Fancellu <luca.fancellu@arm.com>
> Cc: Marc Zyngier <maz@kernel.org>
> ---
>  arch/aarch32/boot.S | 4 ----
>  arch/aarch64/boot.S | 7 -------
>  2 files changed, 11 deletions(-)
> 
> diff --git a/arch/aarch32/boot.S b/arch/aarch32/boot.S
> index 4d16c9c..5c2a183 100644
> --- a/arch/aarch32/boot.S
> +++ b/arch/aarch32/boot.S
> @@ -105,10 +105,6 @@ ASM_FUNC(jump_kernel)
>  	bxeq	lr				@ no EL3
>  
>  	ldr	r4, =SPSR_KERNEL
> -	/* Return in thumb2 mode when bit 0 of address is 1 */
> -	tst	lr, #1
> -	orrne	r4, #PSR_T
> -
>  	msr	spsr_cxf, r4
>  	movs	pc, lr
>  
> diff --git a/arch/aarch64/boot.S b/arch/aarch64/boot.S
> index da5fa65..b889137 100644
> --- a/arch/aarch64/boot.S
> +++ b/arch/aarch64/boot.S
> @@ -136,13 +136,6 @@ ASM_FUNC(jump_kernel)
>  	br	x19			// No EL3
>  
>  1:	mov	x4, #SPSR_KERNEL
> -
> -	/*
> -	 * If bit 0 of the kernel address is set, we're entering in AArch32
> -	 * thumb mode. Set SPSR.T accordingly.
> -	 */
> -	bfi	x4, x19, #5, #1
> -
>  	msr	elr_el3, x19
>  	msr	spsr_el3, x4
>  	eret

Re: [BOOT-WRAPPER 01/11] Always enter AArch32 kernels in ARM mode

[Mark Rutland]

On Fri, Aug 02, 2024 at 12:26:39PM +0100, Andre Przywara wrote:
> On Mon, 29 Jul 2024 17:14:51 +0100
> Mark Rutland <mark.rutland@arm.com> wrote:
> 
> > Currnetly we try to support entering AArch32 kernels, but this is
> 
> I think you are missing "in Thumb mode" here? The read is a bit confusing
> otherwise.
> 
> > unnecessary, and the code is never exercised.
> > 
> > Per Linux's Documentation/arch/arm/booting.txt, AArch32 kernels
> > supported by the AArch64 boot-wrapper should always be entered in ARM
> > mode:
> > 
> > | The boot loader is expected to call the kernel image by jumping
> > | directly to the first instruction of the kernel image.
> > |
> > | On CPUs supporting the ARM instruction set, the entry must be
> > | made in ARM state, even for a Thumb-2 kernel.
> > |
> > | On CPUs supporting only the Thumb instruction set such as
> > | Cortex-M class CPUs, the entry must be made in Thumb state.
> > 
> > Additionally, the kernel__start symbol that we use as the kernel
> > entrypoint is always PHYS_OFFSET + KERNEL_OFFSET, which doesn't take
> > into account any ARM/Thumb distinction in the AArch32 kernel image, and
> > hence we'll never try to set the Thumb bit in the SPSR.
> 
> Is that true? I see the first_spin code path for CPU 0 using those values,
> which indeed never have bit 0 set, but the address could come from *mbox
> as well, given by the live kernel in the PSCI code path, and we don't have
> any control over that.
> Or do I miss anything here?

You're right, and PSCI explicitly describes that bit 0 in the entry
address results in the T bit being set in CPSR.

I will drop this patch, and adjust subsequent paqtches accordingly.

Mark.

> I think the patch is still valid, but we might need to relax the commit
> message here a bit?
> 
> Cheers,
> Andre
> 
> > 
> > Remove the redundant code.
> > 
> > Signed-off-by: Mark Rutland <mark.rutland@arm.com>
> > Cc: Akos Denke <akos.denke@arm.com>
> > Cc: Andre Przywara <andre.przywara@arm.com>
> > Cc: Luca Fancellu <luca.fancellu@arm.com>
> > Cc: Marc Zyngier <maz@kernel.org>
> > ---
> >  arch/aarch32/boot.S | 4 ----
> >  arch/aarch64/boot.S | 7 -------
> >  2 files changed, 11 deletions(-)
> > 
> > diff --git a/arch/aarch32/boot.S b/arch/aarch32/boot.S
> > index 4d16c9c..5c2a183 100644
> > --- a/arch/aarch32/boot.S
> > +++ b/arch/aarch32/boot.S
> > @@ -105,10 +105,6 @@ ASM_FUNC(jump_kernel)
> >  	bxeq	lr				@ no EL3
> >  
> >  	ldr	r4, =SPSR_KERNEL
> > -	/* Return in thumb2 mode when bit 0 of address is 1 */
> > -	tst	lr, #1
> > -	orrne	r4, #PSR_T
> > -
> >  	msr	spsr_cxf, r4
> >  	movs	pc, lr
> >  
> > diff --git a/arch/aarch64/boot.S b/arch/aarch64/boot.S
> > index da5fa65..b889137 100644
> > --- a/arch/aarch64/boot.S
> > +++ b/arch/aarch64/boot.S
> > @@ -136,13 +136,6 @@ ASM_FUNC(jump_kernel)
> >  	br	x19			// No EL3
> >  
> >  1:	mov	x4, #SPSR_KERNEL
> > -
> > -	/*
> > -	 * If bit 0 of the kernel address is set, we're entering in AArch32
> > -	 * thumb mode. Set SPSR.T accordingly.
> > -	 */
> > -	bfi	x4, x19, #5, #1
> > -
> >  	msr	elr_el3, x19
> >  	msr	spsr_el3, x4
> >  	eret
> 

[BOOT-WRAPPER 02/11] aarch64: Remove redundant EL1 entry logic

[Mark Rutland]

For historical reasons the boot-wrapper has code to handle being entered
at Non-secure EL1, but currently this is unsupported and cannot be used
to boot a kernel as jump_kernel() unconditionally writes to SCTLR_EL2,
which will UNDEF.

Remove the logic for handling Non-secure EL1.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Akos Denke <akos.denke@arm.com>
Cc: Andre Przywara <andre.przywara@arm.com>
Cc: Luca Fancellu <luca.fancellu@arm.com>
Cc: Marc Zyngier <maz@kernel.org>
---
 arch/aarch64/boot.S | 17 +----------------
 1 file changed, 1 insertion(+), 16 deletions(-)

diff --git a/arch/aarch64/boot.S b/arch/aarch64/boot.S
index b889137..51ef41b 100644
--- a/arch/aarch64/boot.S
+++ b/arch/aarch64/boot.S
@@ -31,10 +31,8 @@ ASM_FUNC(_start)
 	b.eq	reset_at_el3
 	cmp	x0, #CURRENTEL_EL2
 	b.eq	reset_at_el2
-	cmp	x0, #CURRENTEL_EL1
-	b.eq	reset_at_el1
 
-	/* Booting at EL0 is not supported */
+	/* Booting at EL1 or EL0 is not supported */
 	b	.
 
 	/*
@@ -72,19 +70,6 @@ reset_at_el2:
 	msr	sctlr_el2, x0
 	isb
 
-	b	reset_no_el3
-
-	/*
-	 * EL1 initialization
-	 */
-reset_at_el1:
-	mov_64	x0, SCTLR_EL1_RESET
-	msr	sctlr_el1, x0
-	isb
-
-	b	reset_no_el3
-
-reset_no_el3:
 	cpuid	x0, x1
 	bl	find_logical_id
 	cmp	x0, #MPIDR_INVALID
-- 
2.30.2

[BOOT-WRAPPER 03/11] aarch64: Implement cpu_init_arch()

[Mark Rutland]

When the boot-wrapper is entered at EL2 it does not initialise
CNTFRQ_EL0, and in future it may need to initialize other CPU state
regardless of the exeption level it was entered at.

Use a common cpu_init_arch() function to initialize CPU state regardless
of the exception level the boot-wrapper was entered at.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Akos Denke <akos.denke@arm.com>
Cc: Andre Przywara <andre.przywara@arm.com>
Cc: Luca Fancellu <luca.fancellu@arm.com>
Cc: Marc Zyngier <maz@kernel.org>
---
 arch/aarch64/boot.S |  4 +++-
 arch/aarch64/init.c | 12 +++++++++---
 2 files changed, 12 insertions(+), 4 deletions(-)

diff --git a/arch/aarch64/boot.S b/arch/aarch64/boot.S
index 51ef41b..d8d38dd 100644
--- a/arch/aarch64/boot.S
+++ b/arch/aarch64/boot.S
@@ -51,7 +51,7 @@ reset_at_el3:
 
 	bl	cpu_init_bootwrapper
 
-	bl	cpu_init_el3
+	bl	cpu_init_arch
 
 	bl	gic_secure_init
 
@@ -82,6 +82,8 @@ reset_at_el2:
 
 	bl	cpu_init_bootwrapper
 
+	bl	cpu_init_arch
+
 	b	start_bootmethod
 
 err_invalid_id:
diff --git a/arch/aarch64/init.c b/arch/aarch64/init.c
index c9fc7f1..49abdf7 100644
--- a/arch/aarch64/init.c
+++ b/arch/aarch64/init.c
@@ -52,7 +52,7 @@ static inline bool cpu_has_permission_indirection(void)
 	return mrs(ID_AA64MMFR3_EL1) & mask;
 }
 
-void cpu_init_el3(void)
+static void cpu_init_el3(void)
 {
 	unsigned long scr = SCR_EL3_RES1 | SCR_EL3_NS | SCR_EL3_HCE;
 	unsigned long mdcr = 0;
@@ -153,8 +153,6 @@ void cpu_init_el3(void)
 
 		msr(SMCR_EL3, smcr);
 	}
-
-	msr(CNTFRQ_EL0, COUNTER_FREQ);
 }
 
 #ifdef PSCI
@@ -171,3 +169,11 @@ bool cpu_init_psci_arch(void)
 	return true;
 }
 #endif
+
+void cpu_init_arch(void)
+{
+	if (mrs(CurrentEL) == CURRENTEL_EL3)
+		cpu_init_el3();
+
+	msr(CNTFRQ_EL0, COUNTER_FREQ);
+}
-- 
2.30.2

Re: [BOOT-WRAPPER 03/11] aarch64: Implement cpu_init_arch()

[Marc Zyngier]

On Mon, 29 Jul 2024 17:14:53 +0100,
Mark Rutland <mark.rutland@arm.com> wrote:
> 
> When the boot-wrapper is entered at EL2 it does not initialise
> CNTFRQ_EL0, and in future it may need to initialize other CPU state
> regardless of the exeption level it was entered at.
> 
> Use a common cpu_init_arch() function to initialize CPU state regardless
> of the exception level the boot-wrapper was entered at.
> 
> Signed-off-by: Mark Rutland <mark.rutland@arm.com>
> Cc: Akos Denke <akos.denke@arm.com>
> Cc: Andre Przywara <andre.przywara@arm.com>
> Cc: Luca Fancellu <luca.fancellu@arm.com>
> Cc: Marc Zyngier <maz@kernel.org>
> ---
>  arch/aarch64/boot.S |  4 +++-
>  arch/aarch64/init.c | 12 +++++++++---
>  2 files changed, 12 insertions(+), 4 deletions(-)
> 
> diff --git a/arch/aarch64/boot.S b/arch/aarch64/boot.S
> index 51ef41b..d8d38dd 100644
> --- a/arch/aarch64/boot.S
> +++ b/arch/aarch64/boot.S
> @@ -51,7 +51,7 @@ reset_at_el3:
>  
>  	bl	cpu_init_bootwrapper
>  
> -	bl	cpu_init_el3
> +	bl	cpu_init_arch
>  
>  	bl	gic_secure_init
>  
> @@ -82,6 +82,8 @@ reset_at_el2:
>  
>  	bl	cpu_init_bootwrapper
>  
> +	bl	cpu_init_arch
> +
>  	b	start_bootmethod
>  
>  err_invalid_id:
> diff --git a/arch/aarch64/init.c b/arch/aarch64/init.c
> index c9fc7f1..49abdf7 100644
> --- a/arch/aarch64/init.c
> +++ b/arch/aarch64/init.c
> @@ -52,7 +52,7 @@ static inline bool cpu_has_permission_indirection(void)
>  	return mrs(ID_AA64MMFR3_EL1) & mask;
>  }
>  
> -void cpu_init_el3(void)
> +static void cpu_init_el3(void)
>  {
>  	unsigned long scr = SCR_EL3_RES1 | SCR_EL3_NS | SCR_EL3_HCE;
>  	unsigned long mdcr = 0;
> @@ -153,8 +153,6 @@ void cpu_init_el3(void)
>  
>  		msr(SMCR_EL3, smcr);
>  	}
> -
> -	msr(CNTFRQ_EL0, COUNTER_FREQ);
>  }
>  
>  #ifdef PSCI
> @@ -171,3 +169,11 @@ bool cpu_init_psci_arch(void)
>  	return true;
>  }
>  #endif
> +
> +void cpu_init_arch(void)
> +{
> +	if (mrs(CurrentEL) == CURRENTEL_EL3)
> +		cpu_init_el3();
> +
> +	msr(CNTFRQ_EL0, COUNTER_FREQ);
> +}

Hmmm. This means that you cannot use the BW on a system where EL3 is
implemented, but where you decide to enter at EL2 anyway (the write to
CNTFRQ_EL0 will UNDEF).

I don't care much (I always want the BW to be the first piece of SW to
run), but this is a rather subtle change in behaviour, and we'd better
capture it in the commit message.

With that,

Acked-by: Marc Zyngier <maz@kernel.org>

	M.

-- 
Without deviation from the norm, progress is not possible.

Re: [BOOT-WRAPPER 03/11] aarch64: Implement cpu_init_arch()

[Mark Rutland]

On Fri, Aug 02, 2024 at 10:29:36AM +0100, Marc Zyngier wrote:
> On Mon, 29 Jul 2024 17:14:53 +0100,
> Mark Rutland <mark.rutland@arm.com> wrote:
> > 
> > When the boot-wrapper is entered at EL2 it does not initialise
> > CNTFRQ_EL0, and in future it may need to initialize other CPU state
> > regardless of the exeption level it was entered at.
> > 
> > Use a common cpu_init_arch() function to initialize CPU state regardless
> > of the exception level the boot-wrapper was entered at.
> > 
> > Signed-off-by: Mark Rutland <mark.rutland@arm.com>
> > Cc: Akos Denke <akos.denke@arm.com>
> > Cc: Andre Przywara <andre.przywara@arm.com>
> > Cc: Luca Fancellu <luca.fancellu@arm.com>
> > Cc: Marc Zyngier <maz@kernel.org>
> > ---
> >  arch/aarch64/boot.S |  4 +++-
> >  arch/aarch64/init.c | 12 +++++++++---
> >  2 files changed, 12 insertions(+), 4 deletions(-)
> > 
> > diff --git a/arch/aarch64/boot.S b/arch/aarch64/boot.S
> > index 51ef41b..d8d38dd 100644
> > --- a/arch/aarch64/boot.S
> > +++ b/arch/aarch64/boot.S
> > @@ -51,7 +51,7 @@ reset_at_el3:
> >  
> >  	bl	cpu_init_bootwrapper
> >  
> > -	bl	cpu_init_el3
> > +	bl	cpu_init_arch
> >  
> >  	bl	gic_secure_init
> >  
> > @@ -82,6 +82,8 @@ reset_at_el2:
> >  
> >  	bl	cpu_init_bootwrapper
> >  
> > +	bl	cpu_init_arch
> > +
> >  	b	start_bootmethod
> >  
> >  err_invalid_id:
> > diff --git a/arch/aarch64/init.c b/arch/aarch64/init.c
> > index c9fc7f1..49abdf7 100644
> > --- a/arch/aarch64/init.c
> > +++ b/arch/aarch64/init.c
> > @@ -52,7 +52,7 @@ static inline bool cpu_has_permission_indirection(void)
> >  	return mrs(ID_AA64MMFR3_EL1) & mask;
> >  }
> >  
> > -void cpu_init_el3(void)
> > +static void cpu_init_el3(void)
> >  {
> >  	unsigned long scr = SCR_EL3_RES1 | SCR_EL3_NS | SCR_EL3_HCE;
> >  	unsigned long mdcr = 0;
> > @@ -153,8 +153,6 @@ void cpu_init_el3(void)
> >  
> >  		msr(SMCR_EL3, smcr);
> >  	}
> > -
> > -	msr(CNTFRQ_EL0, COUNTER_FREQ);
> >  }
> >  
> >  #ifdef PSCI
> > @@ -171,3 +169,11 @@ bool cpu_init_psci_arch(void)
> >  	return true;
> >  }
> >  #endif
> > +
> > +void cpu_init_arch(void)
> > +{
> > +	if (mrs(CurrentEL) == CURRENTEL_EL3)
> > +		cpu_init_el3();
> > +
> > +	msr(CNTFRQ_EL0, COUNTER_FREQ);
> > +}
> 
> Hmmm. This means that you cannot use the BW on a system where EL3 is
> implemented, but where you decide to enter at EL2 anyway (the write to
> CNTFRQ_EL0 will UNDEF).
> 
> I don't care much (I always want the BW to be the first piece of SW to
> run), but this is a rather subtle change in behaviour, and we'd better
> capture it in the commit message.

Booting in that way has been explciitly documented as not supported since
January 2022 in commit:

  286b8ecc86393c26 ("Document entry requirements")

... which added documentation to the start of boot.S which says:

| The boot-wrapper must be entered from the reset vector at the
| highest implemented exception level.

.. but regardless I can add some text to the commit message to say that
violating this requirement will now cause a silent failure.

> With that,
> 
> Acked-by: Marc Zyngier <maz@kernel.org>

Thanks!

Mark.

[BOOT-WRAPPER 04/11] aarch64: Always enter kernel via exception return

[Mark Rutland]

When the boot-wrapper is entered at EL3 it will enter the kernel via
ERET, and when entered at EL2 it will branch to the kernel directly.
This is an artifact of the way the boot-wrapper was originally written
in assembly, and it would be preferable to always enter the kernel via
ERET so that PSTATE is always initialized to a known-good value.

Rework jump_kernel() to always enter the kernel via ERET.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Akos Denke <akos.denke@arm.com>
Cc: Andre Przywara <andre.przywara@arm.com>
Cc: Luca Fancellu <luca.fancellu@arm.com>
Cc: Marc Zyngier <maz@kernel.org>
---
 arch/aarch64/boot.S | 27 ++++++++++++---------------
 1 file changed, 12 insertions(+), 15 deletions(-)

diff --git a/arch/aarch64/boot.S b/arch/aarch64/boot.S
index d8d38dd..3dbf85a 100644
--- a/arch/aarch64/boot.S
+++ b/arch/aarch64/boot.S
@@ -76,10 +76,6 @@ reset_at_el2:
 	b.eq	err_invalid_id
 	bl	setup_stack
 
-	mov	w0, #1
-	ldr	x1, =flag_no_el3
-	str	w0, [x1]
-
 	bl	cpu_init_bootwrapper
 
 	bl	cpu_init_arch
@@ -111,25 +107,26 @@ ASM_FUNC(jump_kernel)
 	bl	find_logical_id
 	bl	setup_stack		// Reset stack pointer
 
-	ldr	w0, flag_no_el3
-	cmp	w0, #0			// Prepare Z flag
-
 	mov	x0, x20
 	mov	x1, x21
 	mov	x2, x22
 	mov	x3, x23
+	mov	x4, #SPSR_KERNEL
 
-	b.eq	1f
-	br	x19			// No EL3
+	mrs	x5, CurrentEL
+	cmp	x5, #CURRENTEL_EL3
+	b.eq	eret_at_el3
+	cmp	x5, #CURRENTEL_EL2
+	b.eq	eret_at_el2
+	b	.			// Not possible
 
-1:	mov	x4, #SPSR_KERNEL
+eret_at_el3:
 	msr	elr_el3, x19
 	msr	spsr_el3, x4
 	eret
+eret_at_el2:
+	msr	elr_el2, x19
+	msr	spsr_el2, x4
+	eret
 
 	.ltorg
-
-	.data
-	.align 3
-flag_no_el3:
-	.long 0
-- 
2.30.2

[BOOT-WRAPPER 05/11] aarch32: Refactor inital entry

[Mark Rutland]

For historical reasons the early AArch32 code is structured differently
from the early AArch64 code, with some common code (including stack
setup) performed before we identify the mode we were entered in.

Align the structure of the early AArch32 code with that of the early
AArch64 code. This will make subsequent refactoring easier.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Akos Denke <akos.denke@arm.com>
Cc: Andre Przywara <andre.przywara@arm.com>
Cc: Luca Fancellu <luca.fancellu@arm.com>
Cc: Marc Zyngier <maz@kernel.org>
---
 arch/aarch32/boot.S | 55 ++++++++++++++++++++++++++++-----------------
 1 file changed, 34 insertions(+), 21 deletions(-)

diff --git a/arch/aarch32/boot.S b/arch/aarch32/boot.S
index 5c2a183..43dce75 100644
--- a/arch/aarch32/boot.S
+++ b/arch/aarch32/boot.S
@@ -31,7 +31,28 @@
 	 *   PSCI is not supported when entered in this mode.
 	 */
 ASM_FUNC(_start)
-	/* Stack initialisation */
+	mrs	r0, cpsr
+	and	r0, #PSR_MODE_MASK
+	cmp	r0, #PSR_SVC
+	beq	reset_at_svc
+	cmp	r0, #PSR_HYP
+	beq	reset_at_hyp
+
+	/* Booting at other modes is not supported */
+	b	.
+
+reset_at_svc:
+	/*
+	 * When entered in Secure SVC mode we must switch to monitor mode to
+	 * configure SCR.NS. Switch to monitor mode ASAP to simplify later
+	 * code.
+	 */
+	adr	lr, reset_at_mon
+	ldr	r0, =(PSR_A | PSR_I | PSR_F | PSR_MON)
+	msr	spsr, r0
+	movs	pc, lr
+
+reset_at_mon:
 	cpuid	r0, r1
 	bl	find_logical_id
 	cmp	r0, #MPIDR_INVALID
@@ -39,36 +60,28 @@ ASM_FUNC(_start)
 
 	bl	setup_stack
 
-	mrs	r0, cpsr
-	and	r0, #PSR_MODE_MASK
-
-	cmp	r0, #PSR_HYP
-	bne	_switch_monitor
+	bl	cpu_init_bootwrapper
 
-	mov	r0, #1
-	ldr	r1, =flag_no_el3
-	str	r0, [r1]
+	bl	cpu_init_secure_pl1
 
-	bl	cpu_init_bootwrapper
+	bl	gic_secure_init
 
 	b	start_bootmethod
 
-_switch_monitor:
-	adr	lr, _monitor
-	ldr	r0, =(PSR_A | PSR_I | PSR_F | PSR_MON)
-	msr	spsr, r0
-	movs	pc, lr
+reset_at_hyp:
+	cpuid	r0, r1
+	bl	find_logical_id
+	cmp	r0, #MPIDR_INVALID
+	beq	err_invalid_id
 
-_monitor:
-	/* Move the stack to Monitor mode*/
-	mrs	sp, sp_svc
+	bl	setup_stack
 
-	bl	cpu_init_secure_pl1
+	mov	r0, #1
+	ldr	r1, =flag_no_el3
+	str	r0, [r1]
 
 	bl	cpu_init_bootwrapper
 
-	bl	gic_secure_init
-
 	b	start_bootmethod
 
 err_invalid_id:
-- 
2.30.2

[BOOT-WRAPPER 06/11] aarch32: Implement cpu_init_arch()

[Mark Rutland]

When the boot-wrapper is entered at EL2/Hyp it does not initialise
CNTFRQ, and in future it may need to initialize other CPU state
regardless of the exeption level it was entered at.

Use a common cpu_init_arch() function to initialize CPU state regardless
of the exception level the boot-wrapper was entered at. For clarity
cpu_init_secure_pl1() is renamed to cpu_init_monitor(), which better
matches PSR_MON and will allow for the addition of cppu_init_hyp() and
cpu_init_svc() in future.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Akos Denke <akos.denke@arm.com>
Cc: Andre Przywara <andre.przywara@arm.com>
Cc: Luca Fancellu <luca.fancellu@arm.com>
Cc: Marc Zyngier <maz@kernel.org>
---
 arch/aarch32/boot.S |  4 +++-
 arch/aarch32/init.c | 12 +++++++++---
 2 files changed, 12 insertions(+), 4 deletions(-)

diff --git a/arch/aarch32/boot.S b/arch/aarch32/boot.S
index 43dce75..a6f0751 100644
--- a/arch/aarch32/boot.S
+++ b/arch/aarch32/boot.S
@@ -62,7 +62,7 @@ reset_at_mon:
 
 	bl	cpu_init_bootwrapper
 
-	bl	cpu_init_secure_pl1
+	bl	cpu_init_arch
 
 	bl	gic_secure_init
 
@@ -82,6 +82,8 @@ reset_at_hyp:
 
 	bl	cpu_init_bootwrapper
 
+	bl	cpu_init_arch
+
 	b	start_bootmethod
 
 err_invalid_id:
diff --git a/arch/aarch32/init.c b/arch/aarch32/init.c
index e25f0c7..35da37c 100644
--- a/arch/aarch32/init.c
+++ b/arch/aarch32/init.c
@@ -29,7 +29,7 @@ void announce_arch(void)
 	print_string("\r\n");
 }
 
-void cpu_init_secure_pl1(void)
+static void cpu_init_monitor(void)
 {
 	unsigned long scr = SCR_NS | SCR_HCE;
 	unsigned long nsacr = NSACR_CP10 | NSACR_CP11;
@@ -37,8 +37,6 @@ void cpu_init_secure_pl1(void)
 	mcr(SCR, scr);
 
 	mcr(NSACR, nsacr);
-
-	mcr(CNTFRQ, COUNTER_FREQ);
 }
 
 #ifdef PSCI
@@ -55,3 +53,11 @@ bool cpu_init_psci_arch(void)
 	return true;
 }
 #endif
+
+void cpu_init_arch(void)
+{
+	if (read_cpsr_mode() == PSR_MON)
+		cpu_init_monitor();
+
+	mcr(CNTFRQ, COUNTER_FREQ);
+}
-- 
2.30.2

[BOOT-WRAPPER 07/11] aarch32: Always enter kernel via exception return

[Mark Rutland]

When the boot-wrapper is entered at Seculre PL1 it will enter the kernel
via an exception return, ERET, and when entered at Hyp it will branch to
the kernel directly. This is an artifact of the way the boot-wrapper was
originally written in assembly, and it would be preferable to always
enter the kernel via an exception return so that PSTATE is always
initialized to a known-good value.

Rework jump_kernel() to always enter the kernel via ERET, matching the
stype of the AArch64 version of jump_kernel()

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Akos Denke <akos.denke@arm.com>
Cc: Andre Przywara <andre.przywara@arm.com>
Cc: Luca Fancellu <luca.fancellu@arm.com>
Cc: Marc Zyngier <maz@kernel.org>
---
 arch/aarch32/boot.S | 44 +++++++++++++++++++++++---------------------
 1 file changed, 23 insertions(+), 21 deletions(-)

diff --git a/arch/aarch32/boot.S b/arch/aarch32/boot.S
index a6f0751..11fd7aa 100644
--- a/arch/aarch32/boot.S
+++ b/arch/aarch32/boot.S
@@ -76,10 +76,6 @@ reset_at_hyp:
 
 	bl	setup_stack
 
-	mov	r0, #1
-	ldr	r1, =flag_no_el3
-	str	r0, [r1]
-
 	bl	cpu_init_bootwrapper
 
 	bl	cpu_init_arch
@@ -96,9 +92,10 @@ err_invalid_id:
 	 * r1-r3, sp[0]: kernel arguments
 	 */
 ASM_FUNC(jump_kernel)
-	sub	sp, #4				@ Ignore fourth argument
-	push	{r0 - r3}
-	mov	r5, sp
+	mov	r4, r0
+	mov	r5, r1
+	mov	r6, r2
+	mov	r7, r3
 
 	ldr	r0, =HSCTLR_KERNEL
 	mcr	p15, 4, r0, c1, c0, 0		@ HSCTLR
@@ -111,19 +108,24 @@ ASM_FUNC(jump_kernel)
 	bl	find_logical_id
 	bl	setup_stack
 
-	ldr	lr, [r5], #4
-	ldm	r5, {r0 - r2}
-
-	ldr	r4, =flag_no_el3
-	ldr	r4, [r4]
-	cmp	r4, #1
-	bxeq	lr				@ no EL3
+	mov	r0, r5
+	mov	r1, r6
+	mov	r2, r7
+	ldr	r3, =SPSR_KERNEL
+
+	mrs	r5, cpsr
+	and	r5, #PSR_MODE_MASK
+	cmp	r5, #PSR_MON
+	beq	eret_at_mon
+	cmp	r5, #PSR_HYP
+	beq	eret_at_hyp
+	b	.
 
-	ldr	r4, =SPSR_KERNEL
-	msr	spsr_cxf, r4
+eret_at_mon:
+	mov	lr, r4
+	msr	spsr_cxf, r3
 	movs	pc, lr
-
-	.section .data
-	.align 2
-flag_no_el3:
-	.long 0
+eret_at_hyp:
+	msr	elr_hyp, r4
+	msr	spsr_cxf, r3
+	eret
-- 
2.30.2

[BOOT-WRAPPER 08/11] Unify assembly setup paths

[Mark Rutland]

The early assembly paths for EL3/Secure-PL1 and EL2/Hyp are almost
identical aside from the EL3/Secure-PL1 paths calling gic_secure_init().

Simplify the easlery assembly paths by conditionally calling
gic_secure_init() from cpu_init_arch(), allowing the EL3/Secure-PL1 and
EL2/Hyp paths to be unified.

In order to call gic_secure_init() from C code we need to expose a
prototype for gic_secure_init(), requiring a new <gic.h> header. For
clarity the existing <asm/gic-v3.h> headers are renamed to <asm/gic.h>
and are included through the common header.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Akos Denke <akos.denke@arm.com>
Cc: Andre Przywara <andre.przywara@arm.com>
Cc: Luca Fancellu <luca.fancellu@arm.com>
Cc: Marc Zyngier <maz@kernel.org>
---
 arch/aarch32/boot.S                          | 20 ++++++--------------
 arch/aarch32/include/asm/{gic-v3.h => gic.h} |  2 +-
 arch/aarch32/init.c                          |  5 ++++-
 arch/aarch64/boot.S                          | 17 ++++-------------
 arch/aarch64/include/asm/{gic-v3.h => gic.h} |  2 +-
 arch/aarch64/init.c                          |  5 ++++-
 common/gic-v3.c                              |  2 +-
 common/gic.c                                 |  2 +-
 include/gic.h                                | 16 ++++++++++++++++
 9 files changed, 38 insertions(+), 33 deletions(-)
 rename arch/aarch32/include/asm/{gic-v3.h => gic.h} (91%)
 rename arch/aarch64/include/asm/{gic-v3.h => gic.h} (92%)
 create mode 100644 include/gic.h

diff --git a/arch/aarch32/boot.S b/arch/aarch32/boot.S
index 11fd7aa..3a51cb0 100644
--- a/arch/aarch32/boot.S
+++ b/arch/aarch32/boot.S
@@ -53,22 +53,14 @@ reset_at_svc:
 	movs	pc, lr
 
 reset_at_mon:
-	cpuid	r0, r1
-	bl	find_logical_id
-	cmp	r0, #MPIDR_INVALID
-	beq	err_invalid_id
-
-	bl	setup_stack
-
-	bl	cpu_init_bootwrapper
-
-	bl	cpu_init_arch
-
-	bl	gic_secure_init
-
-	b	start_bootmethod
+	// TODO initialise monitor state
+	b	reset_common
 
 reset_at_hyp:
+	// TODO initialise hyp state
+	b	reset_common
+
+reset_common:
 	cpuid	r0, r1
 	bl	find_logical_id
 	cmp	r0, #MPIDR_INVALID
diff --git a/arch/aarch32/include/asm/gic-v3.h b/arch/aarch32/include/asm/gic.h
similarity index 91%
rename from arch/aarch32/include/asm/gic-v3.h
rename to arch/aarch32/include/asm/gic.h
index b28136a..0b9425d 100644
--- a/arch/aarch32/include/asm/gic-v3.h
+++ b/arch/aarch32/include/asm/gic.h
@@ -1,5 +1,5 @@
 /*
- * arch/aarch32/include/asm/gic-v3.h
+ * arch/aarch32/include/asm/gic.h
  *
  * Copyright (C) 2015 ARM Limited. All rights reserved.
  *
diff --git a/arch/aarch32/init.c b/arch/aarch32/init.c
index 35da37c..cb67bf6 100644
--- a/arch/aarch32/init.c
+++ b/arch/aarch32/init.c
@@ -7,6 +7,7 @@
  * found in the LICENSE.txt file.
  */
 #include <cpu.h>
+#include <gic.h>
 #include <platform.h>
 #include <stdbool.h>
 
@@ -56,8 +57,10 @@ bool cpu_init_psci_arch(void)
 
 void cpu_init_arch(void)
 {
-	if (read_cpsr_mode() == PSR_MON)
+	if (read_cpsr_mode() == PSR_MON) {
 		cpu_init_monitor();
+		gic_secure_init();
+	}
 
 	mcr(CNTFRQ, COUNTER_FREQ);
 }
diff --git a/arch/aarch64/boot.S b/arch/aarch64/boot.S
index 3dbf85a..4cc41bb 100644
--- a/arch/aarch64/boot.S
+++ b/arch/aarch64/boot.S
@@ -43,19 +43,7 @@ reset_at_el3:
 	msr	sctlr_el3, x0
 	isb
 
-	cpuid	x0, x1
-	bl	find_logical_id
-	cmp	x0, #MPIDR_INVALID
-	b.eq	err_invalid_id
-	bl	setup_stack
-
-	bl	cpu_init_bootwrapper
-
-	bl	cpu_init_arch
-
-	bl	gic_secure_init
-
-	b	start_bootmethod
+	b	reset_common
 
 	/*
 	 * EL2 initialization
@@ -70,6 +58,9 @@ reset_at_el2:
 	msr	sctlr_el2, x0
 	isb
 
+	b	reset_common
+
+reset_common:
 	cpuid	x0, x1
 	bl	find_logical_id
 	cmp	x0, #MPIDR_INVALID
diff --git a/arch/aarch64/include/asm/gic-v3.h b/arch/aarch64/include/asm/gic.h
similarity index 92%
rename from arch/aarch64/include/asm/gic-v3.h
rename to arch/aarch64/include/asm/gic.h
index 2447480..9d716f6 100644
--- a/arch/aarch64/include/asm/gic-v3.h
+++ b/arch/aarch64/include/asm/gic.h
@@ -1,5 +1,5 @@
 /*
- * arch/aarch64/include/asm/gic-v3.h
+ * arch/aarch64/include/asm/gic.h
  *
  * Copyright (C) 2015 ARM Limited. All rights reserved.
  *
diff --git a/arch/aarch64/init.c b/arch/aarch64/init.c
index 49abdf7..68c220b 100644
--- a/arch/aarch64/init.c
+++ b/arch/aarch64/init.c
@@ -7,6 +7,7 @@
  * found in the LICENSE.txt file.
  */
 #include <cpu.h>
+#include <gic.h>
 #include <platform.h>
 #include <stdbool.h>
 
@@ -172,8 +173,10 @@ bool cpu_init_psci_arch(void)
 
 void cpu_init_arch(void)
 {
-	if (mrs(CurrentEL) == CURRENTEL_EL3)
+	if (mrs(CurrentEL) == CURRENTEL_EL3) {
 		cpu_init_el3();
+		gic_secure_init();
+	}
 
 	msr(CNTFRQ_EL0, COUNTER_FREQ);
 }
diff --git a/common/gic-v3.c b/common/gic-v3.c
index 6207007..4d8e620 100644
--- a/common/gic-v3.c
+++ b/common/gic-v3.c
@@ -10,7 +10,7 @@
 #include <stdint.h>
 
 #include <cpu.h>
-#include <asm/gic-v3.h>
+#include <gic.h>
 #include <asm/io.h>
 
 #define GICD_CTLR			0x0
diff --git a/common/gic.c b/common/gic.c
index 04d4289..15a3410 100644
--- a/common/gic.c
+++ b/common/gic.c
@@ -10,7 +10,7 @@
 #include <stdint.h>
 
 #include <cpu.h>
-#include <asm/gic-v3.h>
+#include <gic.h>
 #include <asm/io.h>
 
 #define GICD_CTLR			0x0
diff --git a/include/gic.h b/include/gic.h
new file mode 100644
index 0000000..127f82b
--- /dev/null
+++ b/include/gic.h
@@ -0,0 +1,16 @@
+/*
+ * include/gic.h
+ *
+ * Copyright (C) 2024 ARM Limited. All rights reserved.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE.txt file.
+ */
+#ifndef __GIC_H
+#define __GIC_H
+
+#include <asm/gic.h>
+
+void gic_secure_init(void);
+
+#endif
-- 
2.30.2

[BOOT-WRAPPER 09/11] Simplify spin logic

[Mark Rutland]

The logic for initial boot is more complicated than it needs to be,
with both first_spin() having a special case for CPU0 that requires an
additional argument to be passed to spin().

Simplify this by moving the special-case logic for CPU0 into
first_spin(). This removes the need to provide a dummy mailbox for CPU0
to spin on, simplfiies callers of first_spin() and spin(), which no
longer need to pass a dummy mailbox or 'is_entry' for CPU0.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Akos Denke <akos.denke@arm.com>
Cc: Andre Przywara <andre.przywara@arm.com>
Cc: Luca Fancellu <luca.fancellu@arm.com>
Cc: Marc Zyngier <maz@kernel.org>
---
 arch/aarch64/spin.S | 11 +----------
 common/boot.c       | 20 ++++++++------------
 common/psci.c       |  2 +-
 include/boot.h      |  2 +-
 4 files changed, 11 insertions(+), 24 deletions(-)

diff --git a/arch/aarch64/spin.S b/arch/aarch64/spin.S
index 375f732..a7879d4 100644
--- a/arch/aarch64/spin.S
+++ b/arch/aarch64/spin.S
@@ -23,15 +23,6 @@ ASM_FUNC(start_bootmethod)
 	 * Primary CPU (x0 = 0) jumps to kernel, the other ones wait for an
 	 * address to appear in mbox
 	 */
-	adr	x3, mbox
-	adr	x4, kernel_address
-	cmp	x0, #0
-	csel	x1, x3, x4, ne
+	adr	x1, mbox
 	mov	x2, #0
 	bl	first_spin
-
-	.align 3
-kernel_address:
-	.long 0
-
-	.ltorg
diff --git a/common/boot.c b/common/boot.c
index 29d53a4..4417649 100644
--- a/common/boot.c
+++ b/common/boot.c
@@ -27,7 +27,7 @@ const unsigned long id_table[] = { CPU_IDS };
  * @invalid: value of an invalid address, 0 or -1 depending on the boot method
  * @is_entry: when true, pass boot parameters to the kernel, instead of 0
  */
-void __noreturn spin(unsigned long *mbox, unsigned long invalid, int is_entry)
+void __noreturn spin(unsigned long *mbox, unsigned long invalid)
 {
 	unsigned long addr = invalid;
 
@@ -36,13 +36,6 @@ void __noreturn spin(unsigned long *mbox, unsigned long invalid, int is_entry)
 		addr = *mbox;
 	}
 
-	if (is_entry)
-#ifdef KERNEL_32
-		jump_kernel(addr, 0, ~0, (unsigned long)&dtb, 0);
-#else
-		jump_kernel(addr, (unsigned long)&dtb, 0, 0, 0);
-#endif
-
 	jump_kernel(addr, 0, 0, 0, 0);
 
 	unreachable();
@@ -60,12 +53,15 @@ void __noreturn first_spin(unsigned int cpu, unsigned long *mbox,
 			   unsigned long invalid)
 {
 	if (cpu == 0) {
-		*mbox = (unsigned long)&entrypoint;
-		sevl();
-		spin(mbox, invalid, 1);
+		unsigned long addr = (unsigned long)&entrypoint;
+#ifdef KERNEL_32
+		jump_kernel(addr, 0, ~0, (unsigned long)&dtb, 0);
+#else
+		jump_kernel(addr, (unsigned long)&dtb, 0, 0, 0);
+#endif
 	} else {
 		*mbox = invalid;
-		spin(mbox, invalid, 0);
+		spin(mbox, invalid);
 	}
 
 	unreachable();
diff --git a/common/psci.c b/common/psci.c
index 5ae4255..19cc315 100644
--- a/common/psci.c
+++ b/common/psci.c
@@ -57,7 +57,7 @@ static int psci_cpu_off(void)
 
 	branch_table[cpu] = PSCI_ADDR_INVALID;
 
-	spin(branch_table + cpu, PSCI_ADDR_INVALID, 0);
+	spin(branch_table + cpu, PSCI_ADDR_INVALID);
 
 	unreachable();
 }
diff --git a/include/boot.h b/include/boot.h
index 459d1d5..18b805d 100644
--- a/include/boot.h
+++ b/include/boot.h
@@ -12,7 +12,7 @@
 #include <compiler.h>
 #include <stdbool.h>
 
-void __noreturn spin(unsigned long *mbox, unsigned long invalid, int is_entry);
+void __noreturn spin(unsigned long *mbox, unsigned long invalid);
 
 void __noreturn first_spin(unsigned int cpu, unsigned long *mbox,
 			   unsigned long invalid_addr);
-- 
2.30.2

[BOOT-WRAPPER 10/11] Add printing functions

[Mark Rutland]

In subsequent patches we'll want to log messages from specific CPUs. Add
helpers to make this simpler.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Akos Denke <akos.denke@arm.com>
Cc: Andre Przywara <andre.przywara@arm.com>
Cc: Luca Fancellu <luca.fancellu@arm.com>
Cc: Marc Zyngier <maz@kernel.org>
---
 common/platform.c  | 35 +++++++++++++++++++++++++++++++++++
 include/platform.h |  4 ++++
 2 files changed, 39 insertions(+)

diff --git a/common/platform.c b/common/platform.c
index 1607ee6..4e390e1 100644
--- a/common/platform.c
+++ b/common/platform.c
@@ -65,6 +65,41 @@ void print_ulong_hex(unsigned long val)
 	}
 }
 
+// 2^32 is 4,294,967,296
+#define DEC_CHARS_PER_UINT	10
+
+void print_uint_dec(unsigned int val)
+{
+	char digits[DEC_CHARS_PER_UINT];
+	int d = 0;
+
+	do {
+		digits[d] = val % 10;
+		val /= 10;
+		d++;
+	} while (val);
+
+	while (d--) {
+		print_char('0' + digits[d]);
+	}
+}
+
+void print_cpu_warn(unsigned int cpu, const char *str)
+{
+	print_string("CPU");
+	print_uint_dec(cpu);
+	print_string(" WARNING: ");
+	print_string(str);
+}
+
+void print_cpu_msg(unsigned int cpu, const char *str)
+{
+	print_string("CPU");
+	print_uint_dec(cpu);
+	print_string(": ");
+	print_string(str);
+}
+
 void init_uart(void)
 {
 	/*
diff --git a/include/platform.h b/include/platform.h
index c88e124..09712b1 100644
--- a/include/platform.h
+++ b/include/platform.h
@@ -12,6 +12,10 @@
 void print_char(char c);
 void print_string(const char *str);
 void print_ulong_hex(unsigned long val);
+void print_uint_dec(unsigned int val);
+
+void print_cpu_warn(unsigned int cpu, const char *str);
+void print_cpu_msg(unsigned int cpu, const char *str);
 
 void init_uart(void);
 
-- 
2.30.2

[BOOT-WRAPPER 11/11] Boot CPUs sequentially

[Mark Rutland]

Currently the boot-wrapper initializes all CPUs in parallel. This means
that we cannot log errors as they happen, as this would mean multiple
CPUs concurrently writing to the UART, producing garbled output. To
produce meaningful output we have to special-case errors on the boot CPU
and hope CPUs have been configured consistently.

To make it easier to handle errors, boot CPUs sequentially so that errors
can be logged as they happen. With this change it's pretty clear that
the cpu_init_bootmethod() abstraction isn't helpful, and so this is
removed with cpu_init_arch() directly initializing PSCI where necessary.

When things go well this looks like:

| Boot-wrapper v0.2
| Entered at EL3
| Memory layout:
| [0000000080000000..0000000080001f90] => boot-wrapper
| [000000008000fff8..0000000080010000] => mbox
| [0000000080200000..0000000082cbaa00] => kernel
| [0000000088000000..0000000088002df1] => dtb
| CPU0: (MPIDR 0000000000000000) initializing...
| CPU0: Done
| CPU1: (MPIDR 0000000000000100) initializing...
| CPU1: Done
| CPU2: (MPIDR 0000000000000200) initializing...
| CPU2: Done
| CPU3: (MPIDR 0000000000000300) initializing...
| CPU3: Done
| CPU4: (MPIDR 0000000000010000) initializing...
| CPU4: Done
| CPU5: (MPIDR 0000000000010100) initializing...
| CPU5: Done
| CPU6: (MPIDR 0000000000010200) initializing...
| CPU6: Done
| CPU7: (MPIDR 0000000000010300) initializing...
| CPU7: Done
| All CPUs initialized. Entering kernel...
|
| [    0.000000] Booting Linux on physical CPU 0x0000000000 [0x410fd0f0]

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Akos Denke <akos.denke@arm.com>
Cc: Andre Przywara <andre.przywara@arm.com>
Cc: Luca Fancellu <luca.fancellu@arm.com>
Cc: Marc Zyngier <maz@kernel.org>
---
 arch/aarch32/boot.S |  2 --
 arch/aarch32/init.c | 17 +++++++++------
 arch/aarch64/boot.S |  2 --
 arch/aarch64/init.c | 17 +++++++++------
 arch/aarch64/spin.S |  3 ---
 common/init.c       | 50 +++++++++++++++++++++++++++++++++++++--------
 common/psci.c       | 14 -------------
 include/boot.h      |  6 +-----
 8 files changed, 64 insertions(+), 47 deletions(-)

diff --git a/arch/aarch32/boot.S b/arch/aarch32/boot.S
index 3a51cb0..679e28a 100644
--- a/arch/aarch32/boot.S
+++ b/arch/aarch32/boot.S
@@ -70,8 +70,6 @@ reset_common:
 
 	bl	cpu_init_bootwrapper
 
-	bl	cpu_init_arch
-
 	b	start_bootmethod
 
 err_invalid_id:
diff --git a/arch/aarch32/init.c b/arch/aarch32/init.c
index cb67bf6..d08ac83 100644
--- a/arch/aarch32/init.c
+++ b/arch/aarch32/init.c
@@ -6,6 +6,7 @@
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE.txt file.
  */
+#include <boot.h>
 #include <cpu.h>
 #include <gic.h>
 #include <platform.h>
@@ -43,24 +44,28 @@ static void cpu_init_monitor(void)
 #ifdef PSCI
 extern char psci_vectors[];
 
-bool cpu_init_psci_arch(void)
+static void cpu_init_psci_arch(unsigned int cpu)
 {
-	if (read_cpsr_mode() != PSR_MON)
-		return false;
+	if (read_cpsr_mode() != PSR_MON) {
+		print_cpu_warn(cpu, "PSCI could not be initialized (not booted at PL1).\r\n");
+		return;
+	}
 
 	mcr(MVBAR, (unsigned long)psci_vectors);
 	isb();
-
-	return true;
 }
+#else
+static static void cpu_init_psci_arch(unsigned int cpu) { }
 #endif
 
-void cpu_init_arch(void)
+void cpu_init_arch(unsigned int cpu)
 {
 	if (read_cpsr_mode() == PSR_MON) {
 		cpu_init_monitor();
 		gic_secure_init();
 	}
 
+	cpu_init_psci_arch(cpu);
+
 	mcr(CNTFRQ, COUNTER_FREQ);
 }
diff --git a/arch/aarch64/boot.S b/arch/aarch64/boot.S
index 4cc41bb..f8fc808 100644
--- a/arch/aarch64/boot.S
+++ b/arch/aarch64/boot.S
@@ -69,8 +69,6 @@ reset_common:
 
 	bl	cpu_init_bootwrapper
 
-	bl	cpu_init_arch
-
 	b	start_bootmethod
 
 err_invalid_id:
diff --git a/arch/aarch64/init.c b/arch/aarch64/init.c
index 68c220b..81fe33a 100644
--- a/arch/aarch64/init.c
+++ b/arch/aarch64/init.c
@@ -6,6 +6,7 @@
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE.txt file.
  */
+#include <boot.h>
 #include <cpu.h>
 #include <gic.h>
 #include <platform.h>
@@ -159,24 +160,28 @@ static void cpu_init_el3(void)
 #ifdef PSCI
 extern char psci_vectors[];
 
-bool cpu_init_psci_arch(void)
+static void cpu_init_psci_arch(unsigned int cpu)
 {
-	if (mrs(CurrentEL) != CURRENTEL_EL3)
-		return false;
+	if (mrs(CurrentEL) != CURRENTEL_EL3) {
+		print_cpu_warn(cpu, "PSCI could not be initialized (not booted at EL3).\r\n");
+		return;
+	}
 
 	msr(VBAR_EL3, (unsigned long)psci_vectors);
 	isb();
-
-	return true;
 }
+#else
+static void cpu_init_psci_arch(unsigned int cpu);
 #endif
 
-void cpu_init_arch(void)
+void cpu_init_arch(unsigned int cpu)
 {
 	if (mrs(CurrentEL) == CURRENTEL_EL3) {
 		cpu_init_el3();
 		gic_secure_init();
 	}
 
+	cpu_init_psci_arch(cpu);
+
 	msr(CNTFRQ_EL0, COUNTER_FREQ);
 }
diff --git a/arch/aarch64/spin.S b/arch/aarch64/spin.S
index a7879d4..81d7ee4 100644
--- a/arch/aarch64/spin.S
+++ b/arch/aarch64/spin.S
@@ -12,9 +12,6 @@
 
 	.text
 
-ASM_FUNC(cpu_init_bootmethod)
-	ret
-
 ASM_FUNC(start_bootmethod)
 	cpuid	x0, x1
 	bl	find_logical_id
diff --git a/common/init.c b/common/init.c
index 3c05ac3..6197ead 100644
--- a/common/init.c
+++ b/common/init.c
@@ -43,18 +43,50 @@ static void announce_objects(void)
 
 void announce_arch(void);
 
+static void init_bootwrapper(void)
+{
+	init_uart();
+	announce_bootwrapper();
+	announce_arch();
+	announce_objects();
+	init_platform();
+}
+
+static void cpu_init_self(unsigned int cpu)
+{
+	print_string("CPU");
+	print_uint_dec(cpu);
+	print_string(": (MPIDR ");
+	print_ulong_hex(read_mpidr());
+	print_string(") initializing...\r\n");
+
+	cpu_init_arch(cpu);
+
+	print_cpu_msg(cpu, "Done\r\n");
+}
+
 void cpu_init_bootwrapper(void)
 {
+	static volatile unsigned int cpu_next = 0;
 	unsigned int cpu = this_cpu_logical_id();
 
-	if (cpu == 0) {
-		init_uart();
-		announce_bootwrapper();
-		announce_arch();
-		announce_objects();
-		print_string("\r\n");
-		init_platform();
-	}
+	if (cpu == 0)
+		init_bootwrapper();
+
+	while (cpu_next != cpu)
+		wfe();
+
+	cpu_init_self(cpu);
+
+	cpu_next = cpu + 1;
+	dsb(sy);
+	sev();
+
+	if (cpu != 0)
+		return;
+
+	while (cpu_next != NR_CPUS)
+		wfe();
 
-	cpu_init_bootmethod(cpu);
+	print_string("All CPUs initialized. Entering kernel...\r\n\r\n");
 }
diff --git a/common/psci.c b/common/psci.c
index 19cc315..5fe8999 100644
--- a/common/psci.c
+++ b/common/psci.c
@@ -87,17 +87,3 @@ void __noreturn psci_first_spin(void)
 
 	unreachable();
 }
-
-void cpu_init_bootmethod(unsigned int cpu)
-{
-	if (cpu_init_psci_arch())
-		return;
-
-	if (cpu == 0) {
-		print_string("WARNING: PSCI could not be initialized. Boot may fail\r\n\r\n");
-		return;
-	}
-
-	while (1)
-		wfe();
-}
diff --git a/include/boot.h b/include/boot.h
index 18b805d..12c9c5c 100644
--- a/include/boot.h
+++ b/include/boot.h
@@ -17,10 +17,6 @@ void __noreturn spin(unsigned long *mbox, unsigned long invalid);
 void __noreturn first_spin(unsigned int cpu, unsigned long *mbox,
 			   unsigned long invalid_addr);
 
-void cpu_init_bootmethod(unsigned int cpu);
-
-#ifdef PSCI
-bool cpu_init_psci_arch(void);
-#endif
+void cpu_init_arch(unsigned int cpu);
 
 #endif
-- 
2.30.2

Re: [BOOT-WRAPPER 11/11] Boot CPUs sequentially

[Luca Fancellu]

Hi Mark,

> diff --git a/arch/aarch64/init.c b/arch/aarch64/init.c
> index 68c220b..81fe33a 100644
> --- a/arch/aarch64/init.c
> +++ b/arch/aarch64/init.c
> @@ -6,6 +6,7 @@
>  * Use of this source code is governed by a BSD-style license that can be
>  * found in the LICENSE.txt file.
>  */
> +#include <boot.h>
> #include <cpu.h>
> #include <gic.h>
> #include <platform.h>
> @@ -159,24 +160,28 @@ static void cpu_init_el3(void)
> #ifdef PSCI
> extern char psci_vectors[];
> 
> -bool cpu_init_psci_arch(void)
> +static void cpu_init_psci_arch(unsigned int cpu)
> {
> - if (mrs(CurrentEL) != CURRENTEL_EL3)
> - return false;
> + if (mrs(CurrentEL) != CURRENTEL_EL3) {
> + print_cpu_warn(cpu, "PSCI could not be initialized (not booted at EL3).\r\n");
> + return;
> + }
> 
> msr(VBAR_EL3, (unsigned long)psci_vectors);
> isb();
> -
> - return true;
> }
> +#else
> +static void cpu_init_psci_arch(unsigned int cpu);

This needs {} otherwise I’m getting:

| aarch64-poky-linux-ld: arch/aarch64/init.o: in function `cpu_init_arch’:
| /usr/src/debug/boot-wrapper-aarch64/gitAUTOINC+cd7fe8a88e-r0/arch/aarch64/init.c:246: undefined reference to `cpu_init_psci_arch’
| aarch64-poky-linux-ld: /usr/src/debug/boot-wrapper-aarch64/gitAUTOINC+cd7fe8a88e-r0/arch/aarch64/init.c:246: undefined reference to `cpu_init_psci_arch’

When compiling without PSCI.

Cheers,
Luca

Re: [BOOT-WRAPPER 11/11] Boot CPUs sequentially

[Mark Rutland]

On Wed, Jul 31, 2024 at 10:57:34AM +0100, Luca Fancellu wrote:
> Hi Mark,
> 
> > diff --git a/arch/aarch64/init.c b/arch/aarch64/init.c
> > index 68c220b..81fe33a 100644
> > --- a/arch/aarch64/init.c
> > +++ b/arch/aarch64/init.c
> > @@ -6,6 +6,7 @@
> >  * Use of this source code is governed by a BSD-style license that can be
> >  * found in the LICENSE.txt file.
> >  */
> > +#include <boot.h>
> > #include <cpu.h>
> > #include <gic.h>
> > #include <platform.h>
> > @@ -159,24 +160,28 @@ static void cpu_init_el3(void)
> > #ifdef PSCI
> > extern char psci_vectors[];
> >
> > -bool cpu_init_psci_arch(void)
> > +static void cpu_init_psci_arch(unsigned int cpu)
> > {
> > - if (mrs(CurrentEL) != CURRENTEL_EL3)
> > - return false;
> > + if (mrs(CurrentEL) != CURRENTEL_EL3) {
> > + print_cpu_warn(cpu, "PSCI could not be initialized (not booted at EL3).\r\n");
> > + return;
> > + }
> >
> > msr(VBAR_EL3, (unsigned long)psci_vectors);
> > isb();
> > -
> > - return true;
> > }
> > +#else
> > +static void cpu_init_psci_arch(unsigned int cpu);
> 
> This needs {} otherwise I’m getting:
> 
> | aarch64-poky-linux-ld: arch/aarch64/init.o: in function `cpu_init_arch’:
> | /usr/src/debug/boot-wrapper-aarch64/gitAUTOINC+cd7fe8a88e-r0/arch/aarch64/init.c:246: undefined reference to `cpu_init_psci_arch’
> | aarch64-poky-linux-ld: /usr/src/debug/boot-wrapper-aarch64/gitAUTOINC+cd7fe8a88e-r0/arch/aarch64/init.c:246: undefined reference to `cpu_init_psci_arch’
> 
> When compiling without PSCI.

Whoops; I've fixed that up locally. Thanks for the report.

Mark.

Re: [BOOT-WRAPPER 00/11] Cleanup initialization

[Marc Zyngier]

On Mon, 29 Jul 2024 17:14:50 +0100,
Mark Rutland <mark.rutland@arm.com> wrote:
> 
> These patches cleanup the boot-wrapper initialization logic to make it
> more consistent and easier to extend in C code in future. The big
> changes are:
> 
> * The kernel is always entered via an exception return. This allows us
>   to initialize PSTATE consistently, and will allow us to adjust the
>   SPSR dynamically in C code in future if necessary.
> 
> * Regardless of the entered exception level, CPU state is initialized
>   under cpu_init_arch(), allowing for logic to be shared regardless of
>   which exception level was entered.
> 
> * CPUs are initialized sequentially, which allows better for better
>   logging within the boot-wrapper.
> 
> Mark.
> 
> Mark Rutland (11):
>   Always enter AArch32 kernels in ARM mode
>   aarch64: Remove redundant EL1 entry logic
>   aarch64: Implement cpu_init_arch()
>   aarch64: Always enter kernel via exception return
>   aarch32: Refactor inital entry
>   aarch32: Implement cpu_init_arch()
>   aarch32: Always enter kernel via exception return
>   Unify assembly setup paths
>   Simplify spin logic
>   Add printing functions
>   Boot CPUs sequentially
> 
>  arch/aarch32/boot.S                          | 95 ++++++++++----------
>  arch/aarch32/include/asm/{gic-v3.h => gic.h} |  2 +-
>  arch/aarch32/init.c                          | 30 +++++--
>  arch/aarch64/boot.S                          | 66 ++++----------
>  arch/aarch64/include/asm/{gic-v3.h => gic.h} |  2 +-
>  arch/aarch64/init.c                          | 30 +++++--
>  arch/aarch64/spin.S                          | 14 +--
>  common/boot.c                                | 20 ++---
>  common/gic-v3.c                              |  2 +-
>  common/gic.c                                 |  2 +-
>  common/init.c                                | 50 +++++++++--
>  common/platform.c                            | 35 ++++++++
>  common/psci.c                                | 16 +---
>  include/boot.h                               |  8 +-
>  include/gic.h                                | 16 ++++
>  include/platform.h                           |  4 +
>  16 files changed, 221 insertions(+), 171 deletions(-)
>  rename arch/aarch32/include/asm/{gic-v3.h => gic.h} (91%)
>  rename arch/aarch64/include/asm/{gic-v3.h => gic.h} (92%)
>  create mode 100644 include/gic.h

This looks good to me. With the issue reported by Lucas fixed and an
extra comment in patch #3:

Acked-by: Marc Zyngier <maz@kernel.org>

	M.

-- 
Without deviation from the norm, progress is not possible.