| Message ID | 20240111183410.45566-2-julien@xen.org (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | xen/arm32: Improve logging during early boot | expand |
Hi Julien, On 11/01/2024 19:34, Julien Grall wrote: > > > From: Julien Grall <jgrall@amazon.com> > > Since commit 5e213f0f4d2c ("xen/arm32: head: Widen the use of the > temporary mapping"), boot_second (used to cover regions like Xen and > the fixmap) will not be mapped if the identity mapping overlap. > > So it is ok to prepare the fixmap table and link it in boot_second > earlier. With that, the fixmap can also be used earlier via the > temporary mapping. > > Therefore split setup_fixmap() in two: > * The table is now linked in create_page_tables() because > the boot page tables needs to be recreated for every CPU. > * The early UART mapping is only added for the boot CPU0 as the > fixmap table is not cleared when secondary CPUs boot. > > Signed-off-by: Julien Grall <jgrall@amazon.com> Reviewed-by: Michal Orzel <michal.orzel@amd.com> with below 2 adjustments: > > ---- > > Changelog since v1: > * Rebase > * Move the UART mapping enable_mm_boot_cpu() > --- > xen/arch/arm/arm32/mmu/head.S | 61 ++++++++--------------------------- > 1 file changed, 14 insertions(+), 47 deletions(-) > > diff --git a/xen/arch/arm/arm32/mmu/head.S b/xen/arch/arm/arm32/mmu/head.S > index 4e6395e7876d..a90799ad5451 100644 > --- a/xen/arch/arm/arm32/mmu/head.S > +++ b/xen/arch/arm/arm32/mmu/head.S > @@ -165,11 +165,6 @@ > * Rebuild the boot pagetable's first-level entries. The structure > * is described in mm.c. > * > - * After the CPU enables paging it will add the fixmap mapping > - * to these page tables, however this may clash with the 1:1 > - * mapping. So each CPU must rebuild the page tables here with > - * the 1:1 in place. > - * > * Inputs: > * r9 : paddr(start) > * r10: phys offset > @@ -197,6 +192,10 @@ create_page_tables: > add r5, r5, #PAGE_SIZE /* r5 := Next table */ > .endr > > + /* Map the fixmap into boot_second */ > + mov_w r0, FIXMAP_ADDR(0) > + create_table_entry boot_second, xen_fixmap, r0, 2 > + > /* > * Find the size of Xen in pages and multiply by the size of a > * PTE. This will then be compared in the mapping loop below. > @@ -442,19 +441,20 @@ ENDPROC(enable_secondary_cpu_mm) > ENTRY(enable_boot_cpu_mm) > mov r6, lr > > +#ifdef CONFIG_EARLY_PRINTK > + /* > + * Add the UART mapping to the fixmap so the UART can be used > + * as the MMU is on. This only need to do done on the boot CPU. s/need to do done/needs to be done/ > + */ > + mov_w r0, EARLY_UART_VIRTUAL_ADDRESS > + create_mapping_entry xen_fixmap, r0, r11, type=PT_DEV_L3 Would you mind listing r11 in the Input section of a comment? ~Michal
Hi Michal, On 12/01/2024 07:46, Michal Orzel wrote: > On 11/01/2024 19:34, Julien Grall wrote: >> >> >> From: Julien Grall <jgrall@amazon.com> >> >> Since commit 5e213f0f4d2c ("xen/arm32: head: Widen the use of the >> temporary mapping"), boot_second (used to cover regions like Xen and >> the fixmap) will not be mapped if the identity mapping overlap. >> >> So it is ok to prepare the fixmap table and link it in boot_second >> earlier. With that, the fixmap can also be used earlier via the >> temporary mapping. >> >> Therefore split setup_fixmap() in two: >> * The table is now linked in create_page_tables() because >> the boot page tables needs to be recreated for every CPU. >> * The early UART mapping is only added for the boot CPU0 as the >> fixmap table is not cleared when secondary CPUs boot. >> >> Signed-off-by: Julien Grall <jgrall@amazon.com> > Reviewed-by: Michal Orzel <michal.orzel@amd.com> Thanks. > > with below 2 adjustments: I will address them on commit. >> + */ >> + mov_w r0, EARLY_UART_VIRTUAL_ADDRESS >> + create_mapping_entry xen_fixmap, r0, r11, type=PT_DEV_L3 > Would you mind listing r11 in the Input section of a comment? I have added: r11: UART physical address > > ~Michal
diff --git a/xen/arch/arm/arm32/mmu/head.S b/xen/arch/arm/arm32/mmu/head.S index 4e6395e7876d..a90799ad5451 100644 --- a/xen/arch/arm/arm32/mmu/head.S +++ b/xen/arch/arm/arm32/mmu/head.S @@ -165,11 +165,6 @@ * Rebuild the boot pagetable's first-level entries. The structure * is described in mm.c. * - * After the CPU enables paging it will add the fixmap mapping - * to these page tables, however this may clash with the 1:1 - * mapping. So each CPU must rebuild the page tables here with - * the 1:1 in place. - * * Inputs: * r9 : paddr(start) * r10: phys offset @@ -197,6 +192,10 @@ create_page_tables: add r5, r5, #PAGE_SIZE /* r5 := Next table */ .endr + /* Map the fixmap into boot_second */ + mov_w r0, FIXMAP_ADDR(0) + create_table_entry boot_second, xen_fixmap, r0, 2 + /* * Find the size of Xen in pages and multiply by the size of a * PTE. This will then be compared in the mapping loop below. @@ -442,19 +441,20 @@ ENDPROC(enable_secondary_cpu_mm) ENTRY(enable_boot_cpu_mm) mov r6, lr +#ifdef CONFIG_EARLY_PRINTK + /* + * Add the UART mapping to the fixmap so the UART can be used + * as the MMU is on. This only need to do done on the boot CPU. + */ + mov_w r0, EARLY_UART_VIRTUAL_ADDRESS + create_mapping_entry xen_fixmap, r0, r11, type=PT_DEV_L3 +#endif + bl create_page_tables /* Address in the runtime mapping to jump to after the MMU is enabled */ - mov_w lr, 1f - b enable_mmu -1: mov lr, r6 - - /* - * Prepare the fixmap. The function will return to the virtual address - * requested by the caller. - */ - b setup_fixmap + b enable_mmu ENDPROC(enable_boot_cpu_mm) /* @@ -503,39 +503,6 @@ remove_temporary_mapping: mov pc, lr ENDPROC(remove_temporary_mapping) -/* - * Map the UART in the fixmap (when earlyprintk is used) and hook the - * fixmap table in the page tables. - * - * The fixmap cannot be mapped in create_page_tables because it may - * clash with the 1:1 mapping. - * - * Inputs: - * r10: Physical offset - * r11: Early UART base physical address - * - * Clobbers r0 - r4 - */ -setup_fixmap: -#if defined(CONFIG_EARLY_PRINTK) - /* Add UART to the fixmap table */ - mov_w r0, EARLY_UART_VIRTUAL_ADDRESS - create_mapping_entry xen_fixmap, r0, r11, type=PT_DEV_L3 -#endif - /* Map fixmap into boot_second */ - mov_w r0, FIXMAP_ADDR(0) - create_table_entry boot_second, xen_fixmap, r0, 2 - /* Ensure any page table updates made above have occurred. */ - dsb nshst - /* - * The fixmap area will be used soon after. So ensure no hardware - * translation happens before the dsb completes. - */ - isb - - mov pc, lr -ENDPROC(setup_fixmap) - /* Fail-stop */ fail: PRINT("- Boot failed -\r\n") 1: wfe