On 16/01/2024 15:37, Julien Grall wrote:
>
>
> From: Julien Grall <[email protected]>
>
> With the upcoming work to color Xen, the binary will not be anymore
> physically contiguous. This will be a problem during boot as the
> assembly code will need to work out where each piece of Xen reside.
>
> An easy way to solve the issue is to have all code/data accessed
> by the secondary CPUs while the MMU is off within a single page.
>
> Right now, most of the early printk messages are using PRINT() which
> will add the message in .rodata. This is unlikely to be within the
> same page as the rest of the idmap.
>
> So replace all the PRINT() that can be reachable by the secondary
> CPU with MMU-off with PRINT_ID().
>
> Signed-off-by: Julien Grall <[email protected]>
Reviewed-by: Michal Orzel <[email protected]>
with some remarks below
> ---
> xen/arch/arm/arm64/head.S | 14 +++++++-------
> xen/arch/arm/arm64/mmu/head.S | 2 +-
> xen/arch/arm/include/asm/arm64/macros.h | 9 ++++++---
> 3 files changed, 14 insertions(+), 11 deletions(-)
>
> diff --git a/xen/arch/arm/arm64/head.S b/xen/arch/arm/arm64/head.S
> index cfc04c755400..fa8b00b6f1db 100644
> --- a/xen/arch/arm/arm64/head.S
> +++ b/xen/arch/arm/arm64/head.S
> @@ -289,9 +289,9 @@ GLOBAL(init_secondary)
>
> #ifdef CONFIG_EARLY_PRINTK
> ldr x23, =CONFIG_EARLY_UART_BASE_ADDRESS /* x23 := UART base
> address */
> - PRINT("- CPU ")
> + PRINT_ID("- CPU ")
> print_reg x24
> - PRINT(" booting -\r\n")
> + PRINT_ID(" booting -\r\n")
> #endif
> bl check_cpu_mode
> bl cpu_init
> @@ -314,10 +314,10 @@ ENDPROC(init_secondary)
> * Clobbers x0 - x5
> */
> check_cpu_mode:
> - PRINT("- Current EL ")
> + PRINT_ID("- Current EL ")
> mrs x5, CurrentEL
> print_reg x5
> - PRINT(" -\r\n")
> + PRINT_ID(" -\r\n")
>
> /* Are we in EL2 */
> cmp x5, #PSR_MODE_EL2t
> @@ -326,8 +326,8 @@ check_cpu_mode:
> ret
> 1:
> /* OK, we're boned. */
> - PRINT("- Xen must be entered in NS EL2 mode -\r\n")
> - PRINT("- Please update the bootloader -\r\n")
> + PRINT_ID("- Xen must be entered in NS EL2 mode -\r\n")
> + PRINT_ID("- Please update the bootloader -\r\n")
> b fail
What about the PRINT in fail?
> ENDPROC(check_cpu_mode)
>
> @@ -361,7 +361,7 @@ ENDPROC(zero_bss)
> * Clobbers x0 - x3
> */
> cpu_init:
> - PRINT("- Initialize CPU -\r\n")
> + PRINT_ID("- Initialize CPU -\r\n")
>
> /* Set up memory attribute type tables */
> ldr x0, =MAIRVAL
> diff --git a/xen/arch/arm/arm64/mmu/head.S b/xen/arch/arm/arm64/mmu/head.S
> index 92b62ae94ce5..fa40b696ddc8 100644
> --- a/xen/arch/arm/arm64/mmu/head.S
> +++ b/xen/arch/arm/arm64/mmu/head.S
> @@ -276,7 +276,7 @@ ENDPROC(create_page_tables)
> enable_mmu:
> mov x4, x0
> mov x5, x1
> - PRINT("- Turning on paging -\r\n")
> + PRINT_ID("- Turning on paging -\r\n")
>
> /*
> * The state of the TLBs is unknown before turning on the MMU.
> diff --git a/xen/arch/arm/include/asm/arm64/macros.h
> b/xen/arch/arm/include/asm/arm64/macros.h
> index 10e652041f57..6a0108f778a2 100644
> --- a/xen/arch/arm/include/asm/arm64/macros.h
> +++ b/xen/arch/arm/include/asm/arm64/macros.h
> @@ -39,9 +39,12 @@
> * There are multiple flavors:
> * - PRINT_SECT(section, string): The @string will be located in @section
> * - PRINT(): The string will be located in .rodata.str.
> - * - PRINT_ID(): When Xen is running on the Identity Mapping, it is
> - * only possible to have a limited amount of Xen. This will create
> - * the string in .rodata.idmap which will always be mapped.
> + * - PRINT_ID(): This will create the string in .rodata.idmap which
> + * will always be accessible. This is used when:
> + * - Xen is running on the identity mapping because not all of Xen is
> mapped
> + * - Running with the MMU-off on secondary boots as Xen may not be
s/boots/CPUs
> + * physically contiguous in memory (e.g. in the case of cache
> + * coloring).
> *
> * Clobbers x0 - x3
> */
> --
> 2.40.1
>
~Michal
