| Message ID | 20190610193215.23704-10-julien.grall@arm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | xen/arm64: Rework head.S to make it more compliant with the Arm Arm | expand |
On Mon, 10 Jun 2019, Julien Grall wrote: > Adjust the coding style used in the comments within cpu_init(). Take the > opportunity to alter the early print to match the function name. > > Lastly, document the behavior and the main registers usage within the > function. > > Signed-off-by: Julien Grall <julien.grall@arm.com> > --- > xen/arch/arm/arm64/head.S | 19 ++++++++++++++----- > 1 file changed, 14 insertions(+), 5 deletions(-) > > diff --git a/xen/arch/arm/arm64/head.S b/xen/arch/arm/arm64/head.S > index 6aa3148192..ee0024173e 100644 > --- a/xen/arch/arm/arm64/head.S > +++ b/xen/arch/arm/arm64/head.S > @@ -396,19 +396,26 @@ skip_bss: > ret > ENDPROC(zero_bss) > > +/* > + * Initialize the processor for turning the MMU on. > + * > + * Clobbers x0 - x4 Shouldn't it be x0 - x3? The rest looks fine. > + */ > cpu_init: > - PRINT("- Setting up control registers -\r\n") > + PRINT("- Initialize CPU -\r\n") > > /* Set up memory attribute type tables */ > ldr x0, =MAIRVAL > msr mair_el2, x0 > > - /* Set up TCR_EL2: > + /* > + * Set up TCR_EL2: > * PS -- Based on ID_AA64MMFR0_EL1.PARange > * Top byte is used > * PT walks use Inner-Shareable accesses, > * PT walks are write-back, write-allocate in both cache levels, > - * 48-bit virtual address space goes through this table. */ > + * 48-bit virtual address space goes through this table. > + */ > ldr x0, =(TCR_RES1|TCR_SH0_IS|TCR_ORGN0_WBWA|TCR_IRGN0_WBWA|TCR_T0SZ(64-48)) > /* ID_AA64MMFR0_EL1[3:0] (PARange) corresponds to TCR_EL2[18:16] (PS) */ > mrs x1, ID_AA64MMFR0_EL1 > @@ -427,9 +434,11 @@ cpu_init: > ldr x0, =(HSCTLR_BASE) > msr SCTLR_EL2, x0 > > - /* Ensure that any exceptions encountered at EL2 > + /* > + * Ensure that any exceptions encountered at EL2 > * are handled using the EL2 stack pointer, rather > - * than SP_EL0. */ > + * than SP_EL0. > + */ > msr spsel, #1 > ret > ENDPROC(cpu_init) > -- > 2.11.0 >
Hi Stefano, On 26/06/2019 02:01, Stefano Stabellini wrote: > On Mon, 10 Jun 2019, Julien Grall wrote: >> Adjust the coding style used in the comments within cpu_init(). Take the >> opportunity to alter the early print to match the function name. >> >> Lastly, document the behavior and the main registers usage within the >> function. >> >> Signed-off-by: Julien Grall <julien.grall@arm.com> >> --- >> xen/arch/arm/arm64/head.S | 19 ++++++++++++++----- >> 1 file changed, 14 insertions(+), 5 deletions(-) >> >> diff --git a/xen/arch/arm/arm64/head.S b/xen/arch/arm/arm64/head.S >> index 6aa3148192..ee0024173e 100644 >> --- a/xen/arch/arm/arm64/head.S >> +++ b/xen/arch/arm/arm64/head.S >> @@ -396,19 +396,26 @@ skip_bss: >> ret >> ENDPROC(zero_bss) >> >> +/* >> + * Initialize the processor for turning the MMU on. >> + * >> + * Clobbers x0 - x4 > > Shouldn't it be x0 - x3? Yes it should be. I will update the comment. Cheers,
diff --git a/xen/arch/arm/arm64/head.S b/xen/arch/arm/arm64/head.S index 6aa3148192..ee0024173e 100644 --- a/xen/arch/arm/arm64/head.S +++ b/xen/arch/arm/arm64/head.S @@ -396,19 +396,26 @@ skip_bss: ret ENDPROC(zero_bss) +/* + * Initialize the processor for turning the MMU on. + * + * Clobbers x0 - x4 + */ cpu_init: - PRINT("- Setting up control registers -\r\n") + PRINT("- Initialize CPU -\r\n") /* Set up memory attribute type tables */ ldr x0, =MAIRVAL msr mair_el2, x0 - /* Set up TCR_EL2: + /* + * Set up TCR_EL2: * PS -- Based on ID_AA64MMFR0_EL1.PARange * Top byte is used * PT walks use Inner-Shareable accesses, * PT walks are write-back, write-allocate in both cache levels, - * 48-bit virtual address space goes through this table. */ + * 48-bit virtual address space goes through this table. + */ ldr x0, =(TCR_RES1|TCR_SH0_IS|TCR_ORGN0_WBWA|TCR_IRGN0_WBWA|TCR_T0SZ(64-48)) /* ID_AA64MMFR0_EL1[3:0] (PARange) corresponds to TCR_EL2[18:16] (PS) */ mrs x1, ID_AA64MMFR0_EL1 @@ -427,9 +434,11 @@ cpu_init: ldr x0, =(HSCTLR_BASE) msr SCTLR_EL2, x0 - /* Ensure that any exceptions encountered at EL2 + /* + * Ensure that any exceptions encountered at EL2 * are handled using the EL2 stack pointer, rather - * than SP_EL0. */ + * than SP_EL0. + */ msr spsel, #1 ret ENDPROC(cpu_init)
Adjust the coding style used in the comments within cpu_init(). Take the opportunity to alter the early print to match the function name. Lastly, document the behavior and the main registers usage within the function. Signed-off-by: Julien Grall <julien.grall@arm.com> --- xen/arch/arm/arm64/head.S | 19 ++++++++++++++----- 1 file changed, 14 insertions(+), 5 deletions(-)