Hi Ayan, On 27/10/2023 20:07, Ayan Kumar Halder wrote: > Before the MMU is turned on, PC uses physical address. Thus, one can use adr_l > instead of load_paddr to obtain the physical address of a symbol. > > The only exception (for this replacement) is create_table_entry() which is > called before and after MMU is turned on. > > Also, in lookup_processor_type() "r10" is no longer used. The reason being > __lookup_processor_type uses adr_l (thus r10 is no longer used to obtain the > physical address offset). Consequently, there is no need to save/restore r10. > > Signed-off-by: Ayan Kumar Halder <[email protected]> > --- > Refer https://lists.archive.carbon60.com/xen/devel/682900 for details. > > Changes from :- > > v1 :- 1. No need to modify create_table_entry(). > 2. Remove "mov r10, #0 " in lookup_processor_type(). > > v2 :- 1. No need to save/restore r10 in lookup_processor_type(). > 2. Update the commit message title. > > xen/arch/arm/arm32/head.S | 19 ++++++++----------- > 1 file changed, 8 insertions(+), 11 deletions(-) > > diff --git a/xen/arch/arm/arm32/head.S b/xen/arch/arm/arm32/head.S > index 33b038e7e0..1fcc6f745e 100644 > --- a/xen/arch/arm/arm32/head.S > +++ b/xen/arch/arm/arm32/head.S > @@ -171,7 +171,7 @@ past_zImage: > > /* Using the DTB in the .dtb section? */ > .ifnes CONFIG_DTB_FILE,"" > - load_paddr r8, _sdtb > + adr_l r8, _sdtb > .endif > > /* Initialize the UART if earlyprintk has been enabled. */ > @@ -213,7 +213,7 @@ GLOBAL(init_secondary) > mrc CP32(r1, MPIDR) > bic r7, r1, #(~MPIDR_HWID_MASK) /* Mask out flags to get CPU ID */ > > - load_paddr r0, smp_up_cpu > + adr_l r0, smp_up_cpu > dsb > 2: ldr r1, [r0] > cmp r1, r7 > @@ -479,7 +479,7 @@ create_page_tables: > * create_table_entry_paddr() will clobber the register storing > * the physical address of the table to point to. > */ > - load_paddr r5, boot_third > + adr_l r5, boot_third > mov_w r4, XEN_VIRT_START > .rept XEN_NR_ENTRIES(2) > mov r0, r5 /* r0 := paddr(l3 table) */ > @@ -578,7 +578,7 @@ enable_mmu: > flush_xen_tlb_local r0 > > /* Write Xen's PT's paddr into the HTTBR */ > - load_paddr r0, boot_pgtable > + adr_l r0, boot_pgtable > mov r1, #0 /* r0:r1 is paddr (boot_pagetable) */ > mcrr CP64(r0, r1, HTTBR) > isb > @@ -876,11 +876,10 @@ putn: mov pc, lr > > /* This provides a C-API version of __lookup_processor_type */ > ENTRY(lookup_processor_type) > - stmfd sp!, {r4, r10, lr} > - mov r10, #0 /* r10 := offset between virt&phys */ > + stmfd sp!, {r4, lr} > bl __lookup_processor_type > mov r0, r1 > - ldmfd sp!, {r4, r10, pc} > + ldmfd sp!, {r4, pc} > > /* > * Read processor ID register (CP#15, CR0), and Look up in the linker-built > @@ -888,8 +887,6 @@ ENTRY(lookup_processor_type) > * the __proc_info lists since we aren't running with the MMU on (and > therefore, > * we are not in correct address space). We have to calculate the offset. In v2, I mentioned that this comment needs to be tweaked as well. We no longer use load_paddr thus we don't care about the offset. I would remove the comment starting from "Note that...". to avoid confusion or add a proper explanation if you want to keep it. With that addressed: Reviewed-by: Michal Orzel <[email protected]>
~Michal
