xyou
f1a2a110d7
Add the current OS source tree, build scripts, system image layout, and development notes covering DMA page allocation, e1000 bring-up, net API dispatch, and DHCP work in progress.
57 lines
1.6 KiB
C
57 lines
1.6 KiB
C
#include <utsm/utrw.h>
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#include <utsm/segment.h>
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#include <utsm/pckc.h>
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#include <utsm/crypto.h>
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#include <utsm/config.h>
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void *memcpy(void *dst, const void *src, usize len);
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int utsm_read(utsm_capability cap, u64 offset, void *dst, u64 len) {
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if (!dst && len != 0) {
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return UTSM_ERR_INVALID;
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}
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if (len == 0) {
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return UTSM_OK;
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}
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utsm_segment_desc *desc = NULL;
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int status = utsm_cap_validate(cap, UTSM_RIGHT_READ, offset, len, &desc);
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if (status != UTSM_OK) {
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return status;
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}
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utsm_key_material key;
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status = utsm_pckc_get_or_derive(cap.segment_slot, desc, &key);
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if (status != UTSM_OK) {
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return status;
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}
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u8 line_plain[UTSM_CACHE_LINE_SIZE];
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u64 seq_before = desc->writer_seq;
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if (seq_before & 1ULL) {
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return UTSM_ERR_RETRY;
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}
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u64 copied = 0;
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while (copied < len) {
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u64 absolute = offset + copied;
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u64 line_start = (absolute / UTSM_CACHE_LINE_SIZE) * UTSM_CACHE_LINE_SIZE;
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u64 in_line = absolute - line_start;
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u64 chunk = UTSM_CACHE_LINE_SIZE - in_line;
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if (chunk > len - copied) {
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chunk = len - copied;
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}
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u64 line_index = line_start / UTSM_CACHE_LINE_SIZE;
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u64 tweak = utsm_make_tweak(desc->tweak_seed, line_index, desc->key_epoch);
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utsm_crypt_line(&key, tweak, desc->cipher_base + line_start, line_plain);
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memcpy((u8 *)dst + copied, line_plain + in_line, chunk);
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copied += chunk;
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}
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u64 seq_after = desc->writer_seq;
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if (seq_before != seq_after) {
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return UTSM_ERR_RETRY;
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}
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return UTSM_OK;
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}
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