Re: [PATCH v3 06/60] arm64: ptdump: Allow VMALLOC_END to be defined at boot

Mark Rutland
2023-04-28T11:25:35Z

On Tue, Mar 07, 2023 at 03:04:28PM +0100, Ard Biesheuvel wrote:
> Extend the existing pattern for populating ptdump marker entries at
> boot, and add handling of VMALLOC_END, which will cease to be a compile
> time constant for configurations that support 52-bit virtual addressing.
>
> Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
> ---
> arch/arm64/mm/ptdump.c | 8 +++++++-
> 1 file changed, 7 insertions(+), 1 deletion(-)
>
> diff --git a/arch/arm64/mm/ptdump.c b/arch/arm64/mm/ptdump.c
> index 76d28056bd14920a..910b35f02280cbdb 100644
> --- a/arch/arm64/mm/ptdump.c
> +++ b/arch/arm64/mm/ptdump.c
> @@ -31,7 +31,12 @@ enum address_markers_idx {
> PAGE_END_NR,
> #if defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS)
> KASAN_START_NR,
> + KASAN_END_NR,
> #endif
> + MODULES_NR,
> + MODULES_END_NR,
> + VMALLOC_START_NR,
> + VMALLOC_END_NR,
> };

While it'd be a bit more verbose, I reckon it'd be worth making all of this
dynamically initialized. That would naturally handle things which are not
compile-time constant, and it'd keep all the values in one place, so it's
easier to keep the start/end/name/whatever in sync.

Something like:

| enum address_markers_idx {
| MARKER_LINEAR_START,
| MARKER_LINEAR_END,
| #if defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS)
| MARKER_KASAN_START,
| MARKER_KASAN_END,
| #endif
| MARKER_FOO_START,
| MARKER_FOO_END,
| MARKER_BAR_START,
| MARKER_BAR_END,
| MARKER_SENTINEL,
| };
|
| static __ro_after_init struct addr_marker address_markers[] {
| [MARKER_SENTINEL] = {
| .start_address = 0,
| .name = NULL,
| }
| };
|
| static int __init ptdump_init(void)
| {
| address_markers[MARKER_LINEAR_START] = (struct addr_marker) {
| .start_address = [...],
| .name = "Linear mapping start",
| };
| address_markers[MARKER_LINEAR_END] = (struct addr_marker) {
| .start_address = [...],
| .name = "Linear mapping end",
| };
|
| #if defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS)
| address_markers[MARKER_LINEAR_START] = (struct addr_marker) {
| .start_adddress = [...],
| .name = "KASAN shadow start",
| };
| address_markers[MARKER_LINEAR_START] = (struct addr_marker) {
| .start_adddress = [...],
| .name = "KASAN shadow end",
| };
| #endif
|
| [...]
|
| ptdump_initialize();
| ptdump_debugfs_register(&kernel_ptdump_info, "kernel_page_tables");
| return 0;
| };

Thanks,
Mark.

>
> static struct addr_marker address_markers[] = {
> @@ -44,7 +49,7 @@ static struct addr_marker address_markers[] = {
> { MODULES_VADDR, "Modules start" },
> { MODULES_END, "Modules end" },
> { VMALLOC_START, "vmalloc() area" },
> - { VMALLOC_END, "vmalloc() end" },
> + { 0, "vmalloc() end" },
> { VMEMMAP_START, "vmemmap start" },
> { VMEMMAP_START + VMEMMAP_SIZE, "vmemmap end" },
> { PCI_IO_START, "PCI I/O start" },
> @@ -379,6 +384,7 @@ static int __init ptdump_init(void)
> #if defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS)
> address_markers[KASAN_START_NR].start_address = KASAN_SHADOW_START;
> #endif
> + address_markers[VMALLOC_END_NR].start_address = VMALLOC_END;
> ptdump_initialize();
> ptdump_debugfs_register(&kernel_ptdump_info, "kernel_page_tables");
> return 0;
> --
> 2.39.2
>
>