Add a basic software implementation of the ARM64 pagetable walker. This can be used for debugging U-Boot's pagetable, as well as dumping the pagetable from the previous bootloader stage if it used one (by reading out the ttbr address).

One can either call dump_pagetable() to print the pagetable to the console with the default formatter, or implement their own pagetable handler using walke_pagetable() with a custom pte_walker_cb_t callback.

All of the added code is discarded when unused, hence there is no need to add an additional Kconfig option for this.

Signed-off-by: Caleb Connolly caleb.connolly@linaro.org --- arch/arm/cpu/armv8/cache_v8.c | 245 +++++++++++++++++++++++++++++++++++++++ arch/arm/include/asm/armv8/mmu.h | 56 +++++++++ 2 files changed, 301 insertions(+)

diff --git a/arch/arm/cpu/armv8/cache_v8.c b/arch/arm/cpu/armv8/cache_v8.c index d4c64f2d60d9..c3f8dac648ba 100644 --- a/arch/arm/cpu/armv8/cache_v8.c +++ b/arch/arm/cpu/armv8/cache_v8.c @@ -395,8 +395,253 @@ static int count_ranges(void)

return count; }

+#define ALL_ATTRS (3 << 8 | PMD_ATTRINDX_MASK) +#define PTE_IS_TABLE(pte, level) (pte_type(&(pte)) == PTE_TYPE_TABLE && (level) < 3) + +enum walker_state { + WALKER_STATE_START = 0, + WALKER_STATE_TABLE, + WALKER_STATE_REGION, /* block or page, depending on level */ +}; + + +/** + * __pagetable_walk() - Walk through the pagetable and call cb() for each memory region + * + * This is a software implementation of the ARMv8-A MMU translation table walk. As per + * section D5.4 of the ARMv8-A Architecture Reference Manual. It recursively walks the + * 4 or 3 levels of the page table and calls the callback function for each discrete + * region of memory (that being the discovery of a new table, a collection of blocks + * with the same attributes, or of pages with the same attributes). + * + * U-Boot picks the smallest number of virtual address (VA) bits that it can based on the + * memory map configured by the board. If this is less than 39 then the MMU will only use + * 3 levels of translation instead of 3 - skipping level 0. + * + * Each level has 512 entries of 64-bits each. Each entry includes attribute bits and + * an address. When the attribute bits indicate a table, the address is the physical + * address of the table, so we can recursively call _pagetable_walk() on it (after calling + * @cb). If instead they indicate a block or page, we record the start address and attributes + * and continue walking until we find a region with different attributes, or the end of the + * table, in either case we call @cb with the start and end address of the region. + * + * This approach can be used to fully emulate the MMU's translation table walk, as per + * Figure D5-25 of the ARMv8-A Architecture Reference Manual. + * + * @addr: The address of the table to walk + * @tcr: The TCR register value + * @level: The current level of the table + * @cb: The callback function to call for each region + * @priv: Private data to pass to the callback function + */ +static void __pagetable_walk(u64 addr, u64 tcr, int level, pte_walker_cb_t cb, void *priv) +{ + u64 *table = (u64 *)addr; + u64 attrs, last_attrs = 0, last_addr = 0, entry_start = 0; + int i; + u64 va_bits = 64 - (tcr & (BIT(6) - 1)); + static enum walker_state state[4] = { 0 }; + static bool exit; + + if (!level) { + exit = false; + if (va_bits < 39) + level = 1; + } + + state[level] = WALKER_STATE_START; + + /* Walk through the table entries */ + for (i = 0; i < MAX_PTE_ENTRIES; i++) { + u64 pte = table[i]; + u64 _addr = pte & GENMASK_ULL(va_bits, PAGE_SHIFT); + + if (exit) + return; + + if (pte_type(&pte) == PTE_TYPE_FAULT) + continue; + + attrs = pte & ALL_ATTRS; + /* If we're currently inside a block or set of pages */ + if (state[level] > WALKER_STATE_START && state[level] != WALKER_STATE_TABLE) { + /* + * Continue walking if this entry has the same attributes as the last and + * is one page/block away -- it's a contiguous region. + */ + if (attrs == last_attrs && _addr == last_addr + (1 << level2shift(level))) { + last_attrs = attrs; + last_addr = _addr; + continue; + } else { + /* We either hit a table or a new region */ + exit = cb(entry_start, last_addr + (1 << level2shift(level)), + va_bits, level, priv); + if (exit) + return; + state[level] = WALKER_STATE_START; + } + } + last_attrs = attrs; + last_addr = _addr; + + if (PTE_IS_TABLE(pte, level)) { + /* After the end of the table might be corrupted data */ + if (!_addr || (pte & 0xfff) > 0x3ff) + return; + state[level] = WALKER_STATE_TABLE; + /* Signify the start of a table */ + exit = cb(pte, 0, va_bits, level, priv); + if (exit) + return; + + /* Go down a level */ + __pagetable_walk(_addr, tcr, level + 1, cb, priv); + state[level] = WALKER_STATE_START; + } else if (pte_type(&pte) == PTE_TYPE_BLOCK || pte_type(&pte) == PTE_TYPE_PAGE) { + /* We foud a block or page, start walking */ + entry_start = pte; + state[level] = WALKER_STATE_REGION; + } + } + + if (state[level] > WALKER_STATE_START) + exit = cb(entry_start, last_addr + (1 << level2shift(level)), va_bits, level, priv); +} + +static void pretty_print_pte_type(u64 pte) +{ + switch (pte_type(&pte)) { + case PTE_TYPE_FAULT: + printf(" %-5s", "Fault"); + break; + case PTE_TYPE_BLOCK: + printf(" %-5s", "Block"); + break; + case PTE_TYPE_PAGE: + printf(" %-5s", "Pages"); + break; + default: + printf(" %-5s", "Unk"); + } +} + +static void pretty_print_table_attrs(u64 pte) +{ + int ap = (pte & PTE_TABLE_AP) >> 61; + + printf(" | %2s %10s", + (ap & 2) ? "RO" : "", + (ap & 1) ? "!EL0" : ""); + printf(" | %3s %2s %2s", + (pte & PTE_TABLE_PXN) ? "PXN" : "", + (pte & PTE_TABLE_XN) ? "XN" : "", + (pte & PTE_TABLE_NS) ? "NS" : ""); +} + +static void pretty_print_block_attrs(u64 pte) +{ + u64 attrs = pte & PMD_ATTRINDX_MASK; + + switch (attrs) { + case PTE_BLOCK_MEMTYPE(MT_DEVICE_NGNRNE): + printf(" | %-13s", "Device-nGnRnE"); + break; + case PTE_BLOCK_MEMTYPE(MT_DEVICE_NGNRE): + printf(" | %-13s", "Device-nGnRE"); + break; + case PTE_BLOCK_MEMTYPE(MT_DEVICE_GRE): + printf(" | %-13s", "Device-GRE"); + break; + case PTE_BLOCK_MEMTYPE(MT_NORMAL_NC): + printf(" | %-13s", "Normal-NC"); + break; + case PTE_BLOCK_MEMTYPE(MT_NORMAL): + printf(" | %-13s", "Normal"); + break; + default: + printf(" | %-13s", "Unknown"); + } +} + +static void pretty_print_block_memtype(u64 pte) +{ + u64 share = pte & (3 << 8); + + switch (share) { + case PTE_BLOCK_NON_SHARE: + printf(" | %-16s", "Non-shareable"); + break; + case PTE_BLOCK_OUTER_SHARE: + printf(" | %-16s", "Outer-shareable"); + break; + case PTE_BLOCK_INNER_SHARE: + printf(" | %-16s", "Inner-shareable"); + break; + default: + printf(" | %-16s", "Unknown"); + } +} + +static void print_pte(u64 pte, int level) +{ + if (PTE_IS_TABLE(pte, level)) { + printf(" %-5s", "Table"); + pretty_print_table_attrs(pte); + } else { + pretty_print_pte_type(pte); + pretty_print_block_attrs(pte); + pretty_print_block_memtype(pte); + } + printf("\n"); +} + +/** + * pagetable_print_entry() - Callback function to print a single pagetable region + * + * This is the default callback used by @dump_pagetable(). It does some basic pretty + * printing (see example in the U-Boot arm64 documentation). It can be replaced by + * a custom callback function if more detailed information is needed. + * + * @start_attrs: The start address and attributes of the region (or table address) + * @end: The end address of the region (or 0 if it's a table) + * @va_bits: The number of bits used for the virtual address + * @level: The level of the region + * @priv: Private data for the callback (unused) + */ +static bool pagetable_print_entry(u64 start_attrs, u64 end, int va_bits, int level, void *priv) +{ + u64 _addr = start_attrs & GENMASK_ULL(va_bits, PAGE_SHIFT); + int indent = va_bits < 39 ? level - 1 : level; + + printf("%*s", indent * 2, ""); + if (PTE_IS_TABLE(start_attrs, level)) + printf("[%#011llx]%14s", _addr, ""); + else + printf("[%#011llx - %#011llx]", _addr, end); + + printf("%*s | ", (3 - level) * 2, ""); + print_pte(start_attrs, level); + + return false; +} + +void walk_pagetable(u64 ttbr, u64 tcr, pte_walker_cb_t cb, void *priv) +{ + __pagetable_walk(ttbr, tcr, 0, cb, priv); +} + +void dump_pagetable(u64 ttbr, u64 tcr) +{ + u64 va_bits = 64 - (tcr & (BIT(6) - 1)); + + printf("Walking pagetable at %p, va_bits: %lld. Using %d levels\n", (void *)ttbr, + va_bits, va_bits < 39 ? 3 : 4); + walk_pagetable(ttbr, tcr, pagetable_print_entry, NULL); +} + /* Returns the estimated required size of all page tables */ __weak u64 get_page_table_size(void) { u64 one_pt = MAX_PTE_ENTRIES * sizeof(u64); diff --git a/arch/arm/include/asm/armv8/mmu.h b/arch/arm/include/asm/armv8/mmu.h index 52cb18b9ed5e..1348db4204ee 100644 --- a/arch/arm/include/asm/armv8/mmu.h +++ b/arch/arm/include/asm/armv8/mmu.h @@ -128,8 +128,64 @@ static inline void set_ttbr_tcr_mair(int el, u64 table, u64 tcr, u64 attr) } asm volatile("isb"); }

+static inline void get_ttbr_tcr_mair(int el, u64 *table, u64 *tcr, u64 *attr) +{ + if (el == 1) { + asm volatile("mrs %0, ttbr0_el1" : "=r" (*table)); + asm volatile("mrs %0, tcr_el1" : "=r" (*tcr)); + asm volatile("mrs %0, mair_el1" : "=r" (*attr)); + } else if (el == 2) { + asm volatile("mrs %0, ttbr0_el2" : "=r" (*table)); + asm volatile("mrs %0, tcr_el2" : "=r" (*tcr)); + asm volatile("mrs %0, mair_el2" : "=r" (*attr)); + } else if (el == 3) { + asm volatile("mrs %0, ttbr0_el3" : "=r" (*table)); + asm volatile("mrs %0, tcr_el3" : "=r" (*tcr)); + asm volatile("mrs %0, mair_el3" : "=r" (*attr)); + } else { + hang(); + } +} + +/** + * pte_walker_cb_t - callback function for walk_pagetable. + * + * This function is called when the walker finds a table entry + * or after parsing a block or pages. For a table the @end address + * is 0, and @addr is the address of the table. Otherwise, they + * are the start and end physical addresses of the block or page. + * + * @addr: PTE start address (PA), or address of table. Includes attributes. + * @end: End address of the region (or 0 for a table) + * @va_bits: Number of bits in the virtual address + * @level: Table level + * @priv: Private data for the callback + * + * Return: true to stop walking, false to continue + */ +typedef bool (*pte_walker_cb_t)(u64 addr, u64 end, int va_bits, int level, void *priv); + +/** + * walk_pagetable() - Walk the pagetable at ttbr and call @cb for each region + * + * @ttbr: Address of the pagetable to dump + * @tcr: TCR value to use + * @cb: Callback function to call for each entry + * @priv: Private data for the callback + */ +void walk_pagetable(u64 ttbr, u64 tcr, pte_walker_cb_t cb, void *priv); + +/** + * dump_pagetable() - Dump the pagetable at ttbr, printing each region and + * level. + * + * @ttbr: Address of the pagetable to dump + * @tcr: TCR value to use + */ +void dump_pagetable(u64 ttbr, u64 tcr); + struct mm_region { u64 virt; u64 phys; u64 size;