On 2019/11/15 17:07, Peter Zijlstra wrote:
On Fri, Nov 15, 2019 at 02:47:49PM +0800, Shile Zhang wrote:+#if defined(SORTTABLE_64) && defined(UNWINDER_ORC_ENABLED) +/* ORC unwinder only support X86_64 */ +#include <errno.h> +#include <pthread.h> +#include <linux/types.h> + +#define ORC_REG_UNDEFINED 0 +#define ERRSTRING_MAXSZ 256 + +struct orc_entry { + s16 sp_offset; + s16 bp_offset; + unsigned sp_reg:4; + unsigned bp_reg:4; + unsigned type:2; + unsigned end:1; +} __attribute__((packed)); + +struct orctable_info { + size_t orc_size; + size_t orc_ip_size; +} orctable;There's ./arch/x86/include/asm/orc_types.h for this. Please don't duplicate. objtool uses that same header.
Good catch! Thanks for your kindly reminder! I'll remove it.
+/** + * sort - sort an array of elements + * @base: pointer to data to sort + * @num: number of elements + * @size: size of each element + * @cmp_func: pointer to comparison function + * @swap_func: pointer to swap function + * + * This function does a heapsort on the given array. You may provide a + * swap_func function optimized to your element type. + * + * Sorting time is O(n log n) both on average and worst-case. While + * qsort is about 20% faster on average, it suffers from exploitable + * O(n*n) worst-case behavior and extra memory requirements that make + * it less suitable for kernel use. + * + * This code token out of /lib/sort.c. + */ +static void sort(void *base, size_t num, size_t size, + int (*cmp_func)(const void *, const void *), + void (*swap_func)(void *, void *, int size)) +{ + /* pre-scale counters for performance */ + int i = (num/2 - 1) * size, n = num * size, c, r; + + /* heapify */ + for ( ; i >= 0; i -= size) { + for (r = i; r * 2 + size < n; r = c) { + c = r * 2 + size; + if (c < n - size && + cmp_func(base + c, base + c + size) < 0) + c += size; + if (cmp_func(base + r, base + c) >= 0) + break; + swap_func(base + r, base + c, size); + } + } + + /* sort */ + for (i = n - size; i > 0; i -= size) { + swap_func(base, base + i, size); + for (r = 0; r * 2 + size < i; r = c) { + c = r * 2 + size; + if (c < i - size && + cmp_func(base + c, base + c + size) < 0) + c += size; + if (cmp_func(base + r, base + c) >= 0) + break; + swap_func(base + r, base + c, size); + } + } +}Do we really need to copy the heapsort implementation? That is, why not use libc's qsort() ? This is userspace after all.
Yes, I think qsort is better choice than copy-paste here. But qsort does not support customized swap func, which is needed for ORC unwind swap two tables together. I think it's hard to do with qsort, so I used sort same with original orc unwind table sort.
