| Message ID | 20200326032420.27220-12-pasha.tatashin@soleen.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | arm64: MMU enabled kexec relocation | expand |
Hi Pavel, On 26/03/2020 03:24, Pavel Tatashin wrote: > Remove excessive empty lines from arm64_relocate_new_kernel. To make it harder to read? Or just for the churn ... > Also, use comments on the same lines with instructions where > appropriate. Churn, > Change ENDPROC to END it never returns. It might be more useful to convert this to the new style annotations, which should be a separate patch. See Documentation/asm-annotations.rst > copy_page(dest, src, tmps...) > Increments dest and src by PAGE_SIZE, so no need to store dest > prior to calling copy_page and increment it after. Also, src is not > used after a copy, not need to copy either. This bit sounds like cleanup, but I can't isolate it from the noise below.... > Call raw_dcache_line_size() only when relocation is actually going to > happen. Why? The pattern in this code is to setup register that don't change at the top, then do all the work. I think this was an attempt to make it more readable. Nothing branches back to that label, so this is fine, its just less obviously correct. > Since '.align 3' is intended to align globals at the end of the file, > move it there. Please don't make noisy changes to whitespace and comments, its never worth it. Thanks, James > diff --git a/arch/arm64/kernel/relocate_kernel.S b/arch/arm64/kernel/relocate_kernel.S > index c1d7db71a726..e9c974ea4717 100644 > --- a/arch/arm64/kernel/relocate_kernel.S > +++ b/arch/arm64/kernel/relocate_kernel.S > @@ -8,7 +8,6 @@ > > #include <linux/kexec.h> > #include <linux/linkage.h> > - > #include <asm/assembler.h> > #include <asm/kexec.h> > #include <asm/page.h> > @@ -17,25 +16,21 @@ > /* > * arm64_relocate_new_kernel - Put a 2nd stage image in place and boot it. > * > - * The memory that the old kernel occupies may be overwritten when coping the > + * The memory that the old kernel occupies may be overwritten when copying the > * new image to its final location. To assure that the > * arm64_relocate_new_kernel routine which does that copy is not overwritten, > * all code and data needed by arm64_relocate_new_kernel must be between the > * symbols arm64_relocate_new_kernel and arm64_relocate_new_kernel_end. The > * machine_kexec() routine will copy arm64_relocate_new_kernel to the kexec > - * control_code_page, a special page which has been set up to be preserved > - * during the copy operation. > + * safe memory that has been set up to be preserved during the copy operation. > */ > ENTRY(arm64_relocate_new_kernel) > - > /* Setup the list loop variables. */ > mov x18, x2 /* x18 = dtb address */ > mov x17, x1 /* x17 = kimage_start */ > mov x16, x0 /* x16 = kimage_head */ > - raw_dcache_line_size x15, x0 /* x15 = dcache line size */ > mov x14, xzr /* x14 = entry ptr */ > mov x13, xzr /* x13 = copy dest */ > - > /* Clear the sctlr_el2 flags. */ > mrs x0, CurrentEL > cmp x0, #CurrentEL_EL2 > @@ -46,14 +41,11 @@ ENTRY(arm64_relocate_new_kernel) > pre_disable_mmu_workaround > msr sctlr_el2, x0 > isb > -1: > - > - /* Check if the new image needs relocation. */ > +1: /* Check if the new image needs relocation. */ > tbnz x16, IND_DONE_BIT, .Ldone > - > + raw_dcache_line_size x15, x1 /* x15 = dcache line size */ > .Lloop: > and x12, x16, PAGE_MASK /* x12 = addr */ > - > /* Test the entry flags. */ > .Ltest_source: > tbz x16, IND_SOURCE_BIT, .Ltest_indirection > @@ -69,34 +61,18 @@ ENTRY(arm64_relocate_new_kernel) > b.lo 2b > dsb sy > > - mov x20, x13 > - mov x21, x12 > - copy_page x20, x21, x0, x1, x2, x3, x4, x5, x6, x7 > - > - /* dest += PAGE_SIZE */ > - add x13, x13, PAGE_SIZE > + copy_page x13, x12, x0, x1, x2, x3, x4, x5, x6, x7 > b .Lnext > - > .Ltest_indirection: > tbz x16, IND_INDIRECTION_BIT, .Ltest_destination > - > - /* ptr = addr */ > - mov x14, x12 > + mov x14, x12 /* ptr = addr */ > b .Lnext > - > .Ltest_destination: > tbz x16, IND_DESTINATION_BIT, .Lnext > - > - /* dest = addr */ > - mov x13, x12 > - > + mov x13, x12 /* dest = addr */ > .Lnext: > - /* entry = *ptr++ */ > - ldr x16, [x14], #8 > - > - /* while (!(entry & DONE)) */ > - tbz x16, IND_DONE_BIT, .Lloop > - > + ldr x16, [x14], #8 /* entry = *ptr++ */ > + tbz x16, IND_DONE_BIT, .Lloop /* while (!(entry & DONE)) */ > .Ldone: > /* wait for writes from copy_page to finish */ > dsb nsh > @@ -110,16 +86,12 @@ ENTRY(arm64_relocate_new_kernel) > mov x2, xzr > mov x3, xzr > br x17 > - > -ENDPROC(arm64_relocate_new_kernel) > - > .ltorg > - > -.align 3 /* To keep the 64-bit values below naturally aligned. */ > +END(arm64_relocate_new_kernel) > > .Lcopy_end: > .org KEXEC_CONTROL_PAGE_SIZE > - > +.align 3 /* To keep the 64-bit values below naturally aligned. */ > /* > * arm64_relocate_new_kernel_size - Number of bytes to copy to the > * control_code_page. >
diff --git a/arch/arm64/kernel/relocate_kernel.S b/arch/arm64/kernel/relocate_kernel.S index c1d7db71a726..e9c974ea4717 100644 --- a/arch/arm64/kernel/relocate_kernel.S +++ b/arch/arm64/kernel/relocate_kernel.S @@ -8,7 +8,6 @@ #include <linux/kexec.h> #include <linux/linkage.h> - #include <asm/assembler.h> #include <asm/kexec.h> #include <asm/page.h> @@ -17,25 +16,21 @@ /* * arm64_relocate_new_kernel - Put a 2nd stage image in place and boot it. * - * The memory that the old kernel occupies may be overwritten when coping the + * The memory that the old kernel occupies may be overwritten when copying the * new image to its final location. To assure that the * arm64_relocate_new_kernel routine which does that copy is not overwritten, * all code and data needed by arm64_relocate_new_kernel must be between the * symbols arm64_relocate_new_kernel and arm64_relocate_new_kernel_end. The * machine_kexec() routine will copy arm64_relocate_new_kernel to the kexec - * control_code_page, a special page which has been set up to be preserved - * during the copy operation. + * safe memory that has been set up to be preserved during the copy operation. */ ENTRY(arm64_relocate_new_kernel) - /* Setup the list loop variables. */ mov x18, x2 /* x18 = dtb address */ mov x17, x1 /* x17 = kimage_start */ mov x16, x0 /* x16 = kimage_head */ - raw_dcache_line_size x15, x0 /* x15 = dcache line size */ mov x14, xzr /* x14 = entry ptr */ mov x13, xzr /* x13 = copy dest */ - /* Clear the sctlr_el2 flags. */ mrs x0, CurrentEL cmp x0, #CurrentEL_EL2 @@ -46,14 +41,11 @@ ENTRY(arm64_relocate_new_kernel) pre_disable_mmu_workaround msr sctlr_el2, x0 isb -1: - - /* Check if the new image needs relocation. */ +1: /* Check if the new image needs relocation. */ tbnz x16, IND_DONE_BIT, .Ldone - + raw_dcache_line_size x15, x1 /* x15 = dcache line size */ .Lloop: and x12, x16, PAGE_MASK /* x12 = addr */ - /* Test the entry flags. */ .Ltest_source: tbz x16, IND_SOURCE_BIT, .Ltest_indirection @@ -69,34 +61,18 @@ ENTRY(arm64_relocate_new_kernel) b.lo 2b dsb sy - mov x20, x13 - mov x21, x12 - copy_page x20, x21, x0, x1, x2, x3, x4, x5, x6, x7 - - /* dest += PAGE_SIZE */ - add x13, x13, PAGE_SIZE + copy_page x13, x12, x0, x1, x2, x3, x4, x5, x6, x7 b .Lnext - .Ltest_indirection: tbz x16, IND_INDIRECTION_BIT, .Ltest_destination - - /* ptr = addr */ - mov x14, x12 + mov x14, x12 /* ptr = addr */ b .Lnext - .Ltest_destination: tbz x16, IND_DESTINATION_BIT, .Lnext - - /* dest = addr */ - mov x13, x12 - + mov x13, x12 /* dest = addr */ .Lnext: - /* entry = *ptr++ */ - ldr x16, [x14], #8 - - /* while (!(entry & DONE)) */ - tbz x16, IND_DONE_BIT, .Lloop - + ldr x16, [x14], #8 /* entry = *ptr++ */ + tbz x16, IND_DONE_BIT, .Lloop /* while (!(entry & DONE)) */ .Ldone: /* wait for writes from copy_page to finish */ dsb nsh @@ -110,16 +86,12 @@ ENTRY(arm64_relocate_new_kernel) mov x2, xzr mov x3, xzr br x17 - -ENDPROC(arm64_relocate_new_kernel) - .ltorg - -.align 3 /* To keep the 64-bit values below naturally aligned. */ +END(arm64_relocate_new_kernel) .Lcopy_end: .org KEXEC_CONTROL_PAGE_SIZE - +.align 3 /* To keep the 64-bit values below naturally aligned. */ /* * arm64_relocate_new_kernel_size - Number of bytes to copy to the * control_code_page.
Remove excessive empty lines from arm64_relocate_new_kernel. Also, use comments on the same lines with instructions where appropriate. Change ENDPROC to END it never returns. copy_page(dest, src, tmps...) Increments dest and src by PAGE_SIZE, so no need to store dest prior to calling copy_page and increment it after. Also, src is not used after a copy, not need to copy either. Call raw_dcache_line_size() only when relocation is actually going to happen. Since '.align 3' is intended to align globals at the end of the file, move it there. Signed-off-by: Pavel Tatashin <pasha.tatashin@soleen.com> --- arch/arm64/kernel/relocate_kernel.S | 50 +++++++---------------------- 1 file changed, 11 insertions(+), 39 deletions(-)