> -----Original Message-----
> With ARMv8.2-LVA architecture extension availability, arm64 hardware
> which supports this extension can support upto 52-bit virtual
> addresses. It is specially useful for having a 52-bit user-space virtual
> address space while the kernel can still retain 48-bit/52-bit virtual
> addressing.
>
> Since at the moment we enable the support of this extension in the
> kernel via a CONFIG flag (CONFIG_ARM64_VA_BITS_52), so there are
> no clear mechanisms in user-space to determine this CONFIG
> flag value and use it to determine the kernel-space VA address range
> values.
>
> 'makedumpfile' can instead use 'TCR_EL1.T1SZ' value from vmcoreinfo
> which indicates the size offset of the memory region addressed by
> TTBR1_EL1 (and hence can be used for determining the
> vabits_actual value).
>
> The user-space computation for determining whether an address lies in
> the linear map range is the same as we have in kernel-space:
>
> #define __is_lm_address(addr) (!(((u64)addr) & BIT(vabits_actual -
> 1)))
>
> I have sent a kernel patch upstream to add 'TCR_EL1.T1SZ' to
> vmcoreinfo for arm64 (see [0]).
>
> This patch is in accordance with ARMv8 Architecture Reference Manual
> version D.a
>
> Note that with these changes the '--mem-usage' option will not work
> properly for arm64 (a subsequent patch in this series will address the
> same) and there is a discussion on-going with the arm64 maintainers to
> find a way-out for the same (via standard kernel symbols like _stext).
>
> [0].http://lists.infradead.org/pipermail/kexec/2019-November/023962.html
>
> Cc: Kazuhito Hagio <k-ha...@ab.jp.nec.com>
> Cc: John Donnelly <john.p.donne...@oracle.com>
> Cc: kexec@lists.infradead.org
> Signed-off-by: Bhupesh Sharma <bhsha...@redhat.com>
> ---
> arch/arm64.c | 148
> +++++++++++++++++++++++++++++++++++++++++++++------------
> makedumpfile.c | 2 +
> makedumpfile.h | 3 +-
> 3 files changed, 122 insertions(+), 31 deletions(-)
>
> diff --git a/arch/arm64.c b/arch/arm64.c
> index ecb19139e178..094d73b8a60f 100644
> --- a/arch/arm64.c
> +++ b/arch/arm64.c
> @@ -47,6 +47,7 @@ typedef struct {
> static int lpa_52_bit_support_available;
> static int pgtable_level;
> static int va_bits;
> +static int vabits_actual;
> static unsigned long kimage_voffset;
>
> #define SZ_4K 4096
> @@ -218,12 +219,19 @@ pmd_page_paddr(pmd_t pmd)
> #define pte_index(vaddr) (((vaddr) >> PAGESHIFT()) &
> (PTRS_PER_PTE - 1))
> #define pte_offset(dir, vaddr) (pmd_page_paddr((*dir)) +
> pte_index(vaddr) * sizeof(pte_t))
>
> +/*
> + * The linear kernel range starts at the bottom of the virtual address
> + * space. Testing the top bit for the start of the region is a
> + * sufficient check and avoids having to worry about the tag.
> + */
> +#define is_linear_addr(addr) (!(((unsigned long)addr) & (1UL <<
> (vabits_actual - 1))))
Does this check cover 5.3 or earlier kernels?
There is no case that vabits_actual is zero?
> +
> static unsigned long long
> __pa(unsigned long vaddr)
> {
> if (kimage_voffset == NOT_FOUND_NUMBER ||
> - (vaddr >= PAGE_OFFSET))
> - return (vaddr - PAGE_OFFSET + info->phys_base);
> + is_linear_addr(vaddr))
> + return (vaddr + info->phys_base - PAGE_OFFSET);
> else
> return (vaddr - kimage_voffset);
> }
> @@ -253,6 +261,7 @@ static int calculate_plat_config(void)
> (PAGESIZE() == SZ_64K && va_bits == 42)) {
> pgtable_level = 2;
> } else if ((PAGESIZE() == SZ_64K && va_bits == 48) ||
> + (PAGESIZE() == SZ_64K && va_bits == 52) ||
> (PAGESIZE() == SZ_4K && va_bits == 39) ||
> (PAGESIZE() == SZ_16K && va_bits == 47)) {
> pgtable_level = 3;
> @@ -287,6 +296,16 @@ get_phys_base_arm64(void)
> return TRUE;
> }
>
> + /* If both vabits_actual and va_bits are now initialized, always
> + * prefer vabits_actual over va_bits to calculate PAGE_OFFSET
> + * value.
> + */
> + if (vabits_actual && va_bits && vabits_actual != va_bits) {
> + info->page_offset = (-(1UL << vabits_actual));
> + DEBUG_MSG("page_offset : %lx (via vabits_actual)\n",
> + info->page_offset);
> + }
> +
Is this for --mem-usage?
If so, let's drop from this patch and think about it later because
some additional base functions will be needed for the option, I think.
> if (get_num_pt_loads() && PAGE_OFFSET) {
> for (i = 0;
> get_pt_load(i, &phys_start, NULL, &virt_start, NULL);
> @@ -406,6 +425,73 @@ get_stext_symbol(void)
> return(found ? kallsym : FALSE);
> }
>
> +static int
> +get_va_bits_from_stext_arm64(void)
> +{
> + ulong _stext;
> +
> + _stext = get_stext_symbol();
> + if (!_stext) {
> + ERRMSG("Can't get the symbol of _stext.\n");
> + return FALSE;
> + }
> +
> + /* Derive va_bits as per arch/arm64/Kconfig. Note that this is a
> + * best case approximation at the moment, as there can be
> + * inconsistencies in this calculation (for e.g., for
> + * 52-bit kernel VA case, even the 48th bit might be set in
> + * the _stext symbol).
> + *
> + * So, we need to rely on the actual VA_BITS symbol in the
> + * vmcoreinfo for a accurate value.
> + *
> + * TODO: Improve this further once there is a closure with arm64
> + * kernel maintainers on the same.
> + */
> + if ((_stext & PAGE_OFFSET_52) == PAGE_OFFSET_52) {
> + va_bits = 52;
> + } else if ((_stext & PAGE_OFFSET_48) == PAGE_OFFSET_48) {
> + va_bits = 48;
> + } else if ((_stext & PAGE_OFFSET_47) == PAGE_OFFSET_47) {
> + va_bits = 47;
> + } else if ((_stext & PAGE_OFFSET_42) == PAGE_OFFSET_42) {
> + va_bits = 42;
> + } else if ((_stext & PAGE_OFFSET_39) == PAGE_OFFSET_39) {
> + va_bits = 39;
> + } else if ((_stext & PAGE_OFFSET_36) == PAGE_OFFSET_36) {
> + va_bits = 36;
> + } else {
> + ERRMSG("Cannot find a proper _stext for calculating VA_BITS\n");
> + return FALSE;
> + }
> +
> + DEBUG_MSG("va_bits : %d (_stext) (approximation)\n", va_bits);
> +
> + return TRUE;
> +}
> +
> +static void
> +get_page_offset_arm64(void)
> +{
> + /* Check if 'vabits_actual' is initialized yet.
> + * If not, our best bet is to use 'va_bits' to calculate
> + * the PAGE_OFFSET value, otherwise use 'vabits_actual'
> + * for the same.
> + *
> + * See arch/arm64/include/asm/memory.h for more details.
> + */
> + if (!vabits_actual) {
> + info->page_offset = (-(1UL << va_bits));
> + DEBUG_MSG("page_offset : %lx (approximation)\n",
> + info->page_offset);
> + } else {
> + info->page_offset = (-(1UL << vabits_actual));
> + DEBUG_MSG("page_offset : %lx (accurate)\n",
> + info->page_offset);
> + }
Does this support 5.3 or earlier kernels?
Thanks,
Kazu
> +
> +}
> +
> int
> get_machdep_info_arm64(void)
> {
> @@ -420,8 +506,33 @@ get_machdep_info_arm64(void)
> /* Check if va_bits is still not initialized. If still 0, call
> * get_versiondep_info() to initialize the same.
> */
> + if (NUMBER(VA_BITS) != NOT_FOUND_NUMBER) {
> + va_bits = NUMBER(VA_BITS);
> + DEBUG_MSG("va_bits : %d (vmcoreinfo)\n",
> + va_bits);
> + }
> +
> + /* Check if va_bits is still not initialized. If still 0, call
> + * get_versiondep_info() to initialize the same from _stext
> + * symbol.
> + */
> if (!va_bits)
> - get_versiondep_info_arm64();
> + if (get_va_bits_from_stext_arm64() == FALSE)
> + return FALSE;
> +
> + get_page_offset_arm64();
> +
> + /* See TCR_EL1, Translation Control Register (EL1) register
> + * description in the ARMv8 Architecture Reference Manual.
> + * Basically, we can use the TCR_EL1.T1SZ
> + * value to determine the virtual addressing range supported
> + * in the kernel-space (i.e. vabits_actual).
> + */
> + if (NUMBER(tcr_el1_t1sz) != NOT_FOUND_NUMBER) {
> + vabits_actual = 64 - NUMBER(tcr_el1_t1sz);
> + DEBUG_MSG("vabits_actual : %d (vmcoreinfo)\n",
> + vabits_actual);
> + }
>
> if (!calculate_plat_config()) {
> ERRMSG("Can't determine platform config values\n");
> @@ -459,34 +570,11 @@ get_xen_info_arm64(void)
> int
> get_versiondep_info_arm64(void)
> {
> - ulong _stext;
> -
> - _stext = get_stext_symbol();
> - if (!_stext) {
> - ERRMSG("Can't get the symbol of _stext.\n");
> - return FALSE;
> - }
> -
> - /* Derive va_bits as per arch/arm64/Kconfig */
> - if ((_stext & PAGE_OFFSET_36) == PAGE_OFFSET_36) {
> - va_bits = 36;
> - } else if ((_stext & PAGE_OFFSET_39) == PAGE_OFFSET_39) {
> - va_bits = 39;
> - } else if ((_stext & PAGE_OFFSET_42) == PAGE_OFFSET_42) {
> - va_bits = 42;
> - } else if ((_stext & PAGE_OFFSET_47) == PAGE_OFFSET_47) {
> - va_bits = 47;
> - } else if ((_stext & PAGE_OFFSET_48) == PAGE_OFFSET_48) {
> - va_bits = 48;
> - } else {
> - ERRMSG("Cannot find a proper _stext for calculating VA_BITS\n");
> - return FALSE;
> - }
> -
> - info->page_offset = (0xffffffffffffffffUL) << (va_bits - 1);
> + if (!va_bits)
> + if (get_va_bits_from_stext_arm64() == FALSE)
> + return FALSE;
>
> - DEBUG_MSG("va_bits : %d\n", va_bits);
> - DEBUG_MSG("page_offset : %lx\n", info->page_offset);
> + get_page_offset_arm64();
>
> return TRUE;
> }
> diff --git a/makedumpfile.c b/makedumpfile.c
> index 4a000112ba59..baf559e4d74e 100644
> --- a/makedumpfile.c
> +++ b/makedumpfile.c
> @@ -2314,6 +2314,7 @@ write_vmcoreinfo_data(void)
> WRITE_NUMBER("HUGETLB_PAGE_DTOR", HUGETLB_PAGE_DTOR);
> #ifdef __aarch64__
> WRITE_NUMBER("VA_BITS", VA_BITS);
> + WRITE_NUMBER_UNSIGNED("tcr_el1_t1sz", tcr_el1_t1sz);
> WRITE_NUMBER_UNSIGNED("PHYS_OFFSET", PHYS_OFFSET);
> WRITE_NUMBER_UNSIGNED("kimage_voffset", kimage_voffset);
> #endif
> @@ -2720,6 +2721,7 @@ read_vmcoreinfo(void)
> READ_NUMBER("KERNEL_IMAGE_SIZE", KERNEL_IMAGE_SIZE);
> #ifdef __aarch64__
> READ_NUMBER("VA_BITS", VA_BITS);
> + READ_NUMBER_UNSIGNED("tcr_el1_t1sz", tcr_el1_t1sz);
> READ_NUMBER_UNSIGNED("PHYS_OFFSET", PHYS_OFFSET);
> READ_NUMBER_UNSIGNED("kimage_voffset", kimage_voffset);
> #endif
> diff --git a/makedumpfile.h b/makedumpfile.h
> index ac11e906b5b7..7eab6507c8df 100644
> --- a/makedumpfile.h
> +++ b/makedumpfile.h
> @@ -974,7 +974,7 @@ int get_versiondep_info_arm64(void);
> int get_xen_basic_info_arm64(void);
> int get_xen_info_arm64(void);
> unsigned long get_kaslr_offset_arm64(unsigned long vaddr);
> -#define paddr_to_vaddr_arm64(X) (((X) - info->phys_base) | PAGE_OFFSET)
> +#define paddr_to_vaddr_arm64(X) (((X) - (info->phys_base - PAGE_OFFSET)))
>
> #define find_vmemmap() stub_false()
> #define vaddr_to_paddr(X) vaddr_to_paddr_arm64(X)
> @@ -1937,6 +1937,7 @@ struct number_table {
> long KERNEL_IMAGE_SIZE;
> #ifdef __aarch64__
> long VA_BITS;
> + unsigned long tcr_el1_t1sz;
> unsigned long PHYS_OFFSET;
> unsigned long kimage_voffset;
> #endif
> --
> 2.7.4
>
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