Initial commit.

3 files changed, 257 insertions, 0 deletions

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..d3e4a2a
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1 @@
+/vc-log
diff --git a/Makefile b/Makefile
new file mode 100644
index 0000000..b1ff639
--- /dev/null
+++ b/Makefile
@@ -0,0 +1,4 @@
+CFLAGS = -O2 -g
+
+vc-log: vc-log.c
+	$(CC) -std=gnu11 -Wall -Wextra $(CFLAGS) $< -o $@
diff --git a/vc-log.c b/vc-log.c
new file mode 100644
index 0000000..e1e3b63
--- /dev/null
+++ b/vc-log.c
@@ -0,0 +1,252 @@
+// SPDX-License-Identifier: LGPL-3.0-or-later
+
+#include <fcntl.h>
+#include <unistd.h>
+#include <stdio.h>
+#include <stdint.h>
+#include <sys/ioctl.h>
+#include <sys/mman.h>
+#include <stdlib.h>
+#include <string.h>
+
+static int vc_fd;
+static uint32_t vc_mem_size, vc_mem_base, vc_mem_load, vc_mem_phys;
+static void *vc_mem;
+static uint32_t vc_syms_off;
+
+#define VC_MEM_IOC_MAGIC  'v'
+
+#define VC_MEM_IOC_MEM_PHYS_ADDR    _IOR( VC_MEM_IOC_MAGIC, 0, unsigned long )
+#define VC_MEM_IOC_MEM_SIZE         _IOR( VC_MEM_IOC_MAGIC, 1, unsigned int )
+#define VC_MEM_IOC_MEM_BASE         _IOR( VC_MEM_IOC_MAGIC, 2, unsigned int )
+#define VC_MEM_IOC_MEM_LOAD         _IOR( VC_MEM_IOC_MAGIC, 3, unsigned int )
+#define VC_MEM_IOC_MEM_COPY         _IOWR( VC_MEM_IOC_MAGIC, 4, char *)
+
+#define VC_DEBUG_HEADER_OFFSET 0x2800
+#define VC_SYMBOL_BASE_OFFSET VC_DEBUG_HEADER_OFFSET
+
+static void vc_read(void *buf, size_t off, size_t size) {
+	// if(off < vc_mem_base) {
+	// 	fprintf(stderr, "small address\n");
+	// 	abort();
+	// }
+	if(off > vc_mem_size || size > vc_mem_size - off) {
+		fprintf(stderr, "out of bounds read: %zx+%zx/%x\n", off, size, vc_mem_size);
+		abort();
+	}
+
+	if(size == 0) return;
+
+	size_t skip = off % 4;
+	volatile uint32_t *inp = (volatile uint32_t*)((char*)vc_mem + (off - skip));
+	char *out = buf;
+	if(skip) {
+		uint32_t v = *inp;
+		inp++;
+		size_t have = 4 - skip;
+		if(have >= size) {
+			memcpy(out, (char*)&v + skip, size);
+			return;
+		}
+		memcpy(out, (char*)&v + skip, have);
+		out += have;
+		size -= have;
+	}
+
+	while(1) {
+		uint32_t v = *inp;
+		inp++;
+		if(size < 4) {
+			memcpy(out, &v, size);
+			return;
+		}
+		memcpy(out, &v, 4);
+		out += 4;
+		size -= 4;
+	}
+}
+
+static uint32_t vc_read_u32(size_t off) {
+	uint32_t r = 42;
+	vc_read(&r, off, 4);
+	return r;
+}
+
+static uint16_t vc_read_u16(size_t off) {
+	uint16_t r = 42;
+	vc_read(&r, off, 2);
+	return r;
+}
+
+static uint8_t vc_read_u8(size_t off) {
+	uint8_t r = 42;
+	vc_read(&r, off, 1);
+	return r;
+}
+
+static size_t vc_read_ptr(size_t off) {
+	uint32_t r = vc_read_u32(off);
+	if(r == 0) return 0;
+	if(r <= 0xc0000000) {
+		fprintf(stderr, "invalid pointer: %x\n", r);
+		abort();
+	}
+	return r - 0xc0000000;
+}
+
+static char *vc_read_str(size_t off) {
+	size_t len = 0, alloc = 16;
+	char *r = malloc(alloc);
+	if(!r) abort();
+	while(1) {
+		size_t roff = off + len;
+		size_t try_read = alloc - len;
+		if(try_read > vc_mem_size - roff) {
+			try_read = vc_mem_size - roff;
+		}
+		if(try_read == 0) abort();
+		vc_read(r + len, roff, try_read);
+		size_t add = strnlen(r + len, try_read);
+		len += add;
+		if(add < try_read) {
+			break;
+		}
+
+		size_t alloc2 = alloc + (alloc << 2);
+		char *r2 = realloc(r, alloc2);
+		if(!r2) abort();
+		r = r2;
+		alloc = alloc2;
+	}
+
+	return r;
+}
+
+static void vc_open(void) {
+	int r = open("/dev/vc-mem", O_RDWR | O_SYNC | O_CLOEXEC);
+	if(r < 0) {
+		perror("open");
+		abort();
+	}
+	vc_fd = r;
+
+	r = ioctl(vc_fd, VC_MEM_IOC_MEM_SIZE, &vc_mem_size);
+	if(r < 0) {
+		perror("VC_MEM_IOC_MEM_SIZE");
+		abort();
+	}
+	r = ioctl(vc_fd, VC_MEM_IOC_MEM_BASE, &vc_mem_base);
+	if(r < 0) {
+		perror("VC_MEM_IOC_MEM_BASE");
+		abort();
+	}
+	r = ioctl(vc_fd, VC_MEM_IOC_MEM_LOAD, &vc_mem_load);
+	if(r < 0) {
+		perror("VC_MEM_IOC_MEM_LOAD");
+		abort();
+	}
+	r = ioctl(vc_fd, VC_MEM_IOC_MEM_PHYS_ADDR, &vc_mem_phys);
+	if(r < 0) {
+		perror("VC_MEM_IOC_MEM_PHYS_ADDR");
+		abort();
+	}
+
+	vc_mem = mmap(NULL, vc_mem_size, PROT_READ | PROT_WRITE, MAP_SHARED, vc_fd, 0);
+	if(vc_mem == MAP_FAILED) {
+		perror("mmap");
+		abort();
+	}
+
+	uint32_t dbg_off = vc_mem_load + VC_DEBUG_HEADER_OFFSET;
+	uint32_t dbg_magic = vc_read_u32(dbg_off + 4);
+	if(dbg_magic != 0x48444356) {
+		fprintf(stderr, "bad debug magic: %x, expected 48444356\n", dbg_magic);
+		abort();
+	}
+	vc_syms_off = vc_read_u32(dbg_off);
+}
+
+static size_t vc_sym_find(const char *want) {
+	uint32_t at = vc_syms_off;
+	while(1) {
+		uint32_t label = vc_read_u32(at + 0);
+		uint32_t addr = vc_read_u32(at + 4);
+		if(label == 0) return 0;
+
+		char *name = vc_read_str(label);
+		int r = strcmp(name, want);
+		free(name);
+		if(!r) return addr;
+
+		at += 12;
+	}
+}
+
+static void vc_log_read(size_t descriptor_ptr) {
+	uint8_t fmt = vc_read_u8(descriptor_ptr);
+	size_t ptr = vc_read_ptr(descriptor_ptr + 4);
+	if(!ptr) {
+		printf("no data\n");
+	}
+	if(fmt != 1) {
+		printf("unsupported log format %u\n", fmt);
+		return;
+	}
+
+	uint32_t magic = vc_read_u32(ptr);
+	if(magic != 0x5353454d) {
+		printf("bad magic %x, wanted 5353454d", magic);
+		return;
+	}
+
+	size_t l_start = vc_read_ptr(ptr + 4);
+	size_t l_end = vc_read_ptr(ptr + 8);
+	size_t l_ptr = vc_read_ptr(ptr + 12);
+	size_t l_next_msg = vc_read_ptr(ptr + 16);
+
+	size_t at = l_next_msg;
+	do {
+		uint32_t time = vc_read_u32(at + 0);
+		uint32_t seq = vc_read_u16(at + 4);
+		size_t size = vc_read_u16(at + 6);
+		if(size < 12) {
+			printf("short message: %zu\n", size);
+			return;
+		}
+		size_t len = size - 12;
+		char *s = malloc(len + 1);
+		if(!s) abort();
+		vc_read(s, at + 12, len);
+		s[len] = 0;
+		printf("[%u : %u] %s\n", time, seq, s);
+		free(s);
+
+		at += size;
+		if(at == l_end) at = l_start;
+	} while(at != l_ptr);
+}
+
+static void vc_log_read_all(void) {
+	size_t log_start = vc_sym_find("__LOG_START");
+	if(!log_start) {
+		fprintf(stderr, "no __LOG_START\n");
+		abort();
+	}
+	log_start = vc_read_ptr(log_start);
+
+	uint32_t log_magic = vc_read_u32(log_start);
+	if(log_magic != 0x564c4f47) {
+		fprintf(stderr, "bad log magic: %x, wanted 4c4f4756\n", log_magic);
+		abort();
+	}
+
+	vc_log_read(log_start + 40);
+}
+
+int main() {
+	vc_open();
+	vc_log_read_all();
+
+	close(vc_fd);
+	return 0;
+}