| Message ID | 20240812101555.3558589-4-mark.rutland@arm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Cleanup initialization | expand |
On Mon, 12 Aug 2024 11:15:48 +0100 Mark Rutland <mark.rutland@arm.com> wrote: > 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. That looks fine and still boots when entered in EL2 or EL3. Just one nit below, with that: Reviewed-by: Andre Przywara <andre.przywara@arm.com> > > Signed-off-by: Mark Rutland <mark.rutland@arm.com> > Acked-by: Marc Zyngier <maz@kernel.org> > Cc: Akos Denke <akos.denke@arm.com> > Cc: Andre Przywara <andre.przywara@arm.com> > Cc: Luca Fancellu <luca.fancellu@arm.com> > --- > arch/aarch64/boot.S | 30 +++++++++++++----------------- > 1 file changed, 13 insertions(+), 17 deletions(-) > > diff --git a/arch/aarch64/boot.S b/arch/aarch64/boot.S > index 52c617d..0ac0c98 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 > @@ -111,18 +107,11 @@ 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 > - > - b.eq 1f > - br x19 // No EL3 > - > -1: mov x4, #SPSR_KERNEL > + mov x4, #SPSR_KERNEL > > /* > * If bit 0 of the kernel address is set, we're entering in AArch32 > @@ -130,13 +119,20 @@ ASM_FUNC(jump_kernel) > */ > bfi x4, x19, #5, #1 > > + mrs x5, CurrentEL > + cmp x5, #CURRENTEL_EL3 > + b.eq eret_at_el3 > + cmp x5, #CURRENTEL_EL2 > + b.eq eret_at_el2 > + b . // Not possible > + > +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 Looks like we don't need this directive anymore. Cheers, Andre > - > - .data > - .align 3 > -flag_no_el3: > - .long 0
diff --git a/arch/aarch64/boot.S b/arch/aarch64/boot.S index 52c617d..0ac0c98 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 @@ -111,18 +107,11 @@ 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 - - b.eq 1f - br x19 // No EL3 - -1: mov x4, #SPSR_KERNEL + mov x4, #SPSR_KERNEL /* * If bit 0 of the kernel address is set, we're entering in AArch32 @@ -130,13 +119,20 @@ ASM_FUNC(jump_kernel) */ bfi x4, x19, #5, #1 + mrs x5, CurrentEL + cmp x5, #CURRENTEL_EL3 + b.eq eret_at_el3 + cmp x5, #CURRENTEL_EL2 + b.eq eret_at_el2 + b . // Not possible + +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