74 lines
1.5 KiB
C
74 lines
1.5 KiB
C
#include <cheriintrin.h>
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#include <stdint.h>
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#include <stddef.h>
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#define HEAP_SIZE 4096
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static char heap[HEAP_SIZE];
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static size_t bump = 0;
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// Add delta value for TLB translation
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static inline void * __capability add_delta(void * __capability cap, int offset) {
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void * __capability result;
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asm volatile (
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"candperm %0, %1, %2"
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: "=C" (result) // Output: %0 (result)
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: "C" (cap), // Input: %1 (original cap)
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"r" (offset) // Input: %2 (offset register)
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: // No clobbered registers
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);
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return result;
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}
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void * __capability malloc(size_t size) {
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// Align to 8 bytes (important for capability safety)
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size = (size + 7) & ~7;
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if (bump + size > HEAP_SIZE)
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return NULL;
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void * __capability base = cheri_ddc_get();
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uintptr_t addr = (uintptr_t)(heap + bump);
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// Create capability to this region
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void * __capability cap = cheri_address_set(base, addr);
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// Enforce bounds (this is the key CHERI feature)
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cap = cheri_bounds_set(cap, size);
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// Hard-coded delta value
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cap = add_delta(cap, 4);
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bump += size;
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return cap;
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}
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void bump_reset(void) {
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bump = 0;
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}
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int main(void) {
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char * __capability a = malloc(30);
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char * __capability b = malloc(16);
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if (!a || !b) return -1;
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a[0] = 'A';
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a[1] = 'C';
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b[0] = 'B';
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// This will fault (out-of-bounds)
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// a[20] = 'X';
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if (a[1] != 'C') {
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while (1);
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}
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return 0;
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} |