I have a linker script:
SECTIONS
{
.text 0x42000:
{
*(.text*)
}
aligned_dot = ALIGN(0x10 * 1024);
.data aligned_dot :
{
*(.data*)
}
}
If I link a (very simple) file using this it gives what I would expect:
Sections:
Idx Name Size Address Type
0 00000000 0000000000000000
1 .text 00000008 0000000000042000 TEXT DATA
2 .data 00000000 0000000000044000 TEXT BSS
And aligned_dot is:
00044000 A aligned_dot
However, I'd like to use a MEMORY command like this:
MEMORY
{
ram (wxa) : ORIGIN = 0x42000, LENGTH = 0x100000
}
SECTIONS
{
.text :
{
*(.text*)
}
aligned_dot = ALIGN(0x10 * 1024);
.data aligned_dot :
{
*(.data*)
}
}
When I link using this script, it seems like the address of the .data section is ignored!
Sections:
Idx Name Size Address Type
0 00000000 0000000000000000
1 .text 00000008 0000000000042000 TEXT DATA
2 .data 00000000 0000000000042008 TEXT BSS
Even though aligned_dot is still:
00044000 A aligned_dot
That is weird right? What is going on? This is using Clang's LLD.
I think this might be a bug in LLVM. In LinkerScript.cpp we have:
void LinkerScript::assignOffsets(OutputSection *Sec) {
if (!(Sec->Flags & SHF_ALLOC))
Dot = 0;
else if (Sec->AddrExpr)
setDot(Sec->AddrExpr, Sec->Location, false);
Ctx->MemRegion = Sec->MemRegion;
Ctx->LMARegion = Sec->LMARegion;
if (Ctx->MemRegion)
Dot = Ctx->MemRegion->CurPos;
Which looks to me like it ignores the AddrExpr if MemRegion is set. If I change the penultimate line to this then it works fine:
if (Ctx->MemRegion && !Sec->AddrExpr)
Edit: Seems like this was not enough if there are sections after your manually address one. You need something like this, though I am even less sure about this:
void LinkerScript::assignOffsets(OutputSection *Sec) {
if (!(Sec->Flags & SHF_ALLOC))
Dot = 0;
else if (Sec->AddrExpr)
setDot(Sec->AddrExpr, Sec->Location, false);
Ctx->MemRegion = Sec->MemRegion;
Ctx->LMARegion = Sec->LMARegion;
if (Ctx->MemRegion && !Sec->AddrExpr)
Dot = Ctx->MemRegion->CurPos;
switchTo(Sec);
if (Ctx->MemRegion && Sec->AddrExpr) {
if (Ctx->MemRegion->CurPos < Dot) {
expandMemoryRegions(Dot - Ctx->MemRegion->CurPos);
}
}
Related
I have section in LDS script file
MEMORY
{
boot (r) : ORIGIN = 0x00000000, LENGTH = 0x10000
flash (rx) : ORIGIN = 0x00010000, LENGTH = 1080K
tcm (rw!x) : ORIGIN = 0x003F0000, LENGTH = 60k
itcm (rwx) : ORIGIN = 0x003FF000, LENGTH = 4k
ram (rw!x) : ORIGIN = 0x00400100, LENGTH = 192k - 0x100
}
SECTIONS
{
.tcm ALIGN(8) :
{
/* some other files */
*ate_app*.o(.bss .bss.* .scommon .sbss .dynbss COMMON)
/* some other files */
}>tcm AT>flash
/* other sections */
}
When my output file is ate_app.elf then linking fails with .tcm section overlap error.
When I change output name to qwerty.elf or change the ate_app.o directive to something else linking goes successfuly.
Why is this strange behavior?
I wrote the following code and declared it in ITCM.
static void __attribute__((section(".itcm"))) TxMain(ULONG thread_input)
{
uint8_t i = 0;
for (;;)
{
i++;
if(i == 100){
i = 0;
tx_thread_sleep(100); /* go to sleep 100ms. */
}
}
}
My ld script has the following statement.
/* Specify the memory areas */
MEMORY
{
DTCMRAM (xrw) : ORIGIN = 0x20000000, LENGTH = 128K
RAM_D1 (xrw) : ORIGIN = 0x24000000, LENGTH = 512K
RAM_D2 (xrw) : ORIGIN = 0x30000000, LENGTH = 288K
RAM_D3 (xrw) : ORIGIN = 0x38000000, LENGTH = 64K
ITCMRAM (xrw) : ORIGIN = 0x00000000, LENGTH = 64K
FLASH (rx) : ORIGIN = 0x8000000, LENGTH = 2048K
}
/* Define output sections */
SECTIONS
{
.itcm :
{
. = ALIGN(4);
*(.itcm)
*(.itcm*)
. = ALIGN(4);
} >ITCMRAM
/* ... others ... */
}
When I run it, I check that TxMain is at 0xC, which is normal, but when I run tx_thread_sleep, it indicates that it is at 0x18, when in fact it is in Flash, i.e. at address 0x2000 ???? in the Flash,
screenshot with itcm exec
When itcm is not declared, the address is taken normally.
screenshot without itcm exec
I have an example program I am running here to see if the substring matches the string and then print them out. So far, I am having trouble running the program due to a bad address. I am wondering if there is a way to fix this problem? I have attached the entire code but my problem is mostly related to isSubstring.
#include <uapi/linux/bpf.h>
#define ARRAYSIZE 64
struct data_t {
char buf[ARRAYSIZE];
};
BPF_ARRAY(lookupTable, struct data_t, ARRAYSIZE);
//char name[20];
//find substring in a string
static bool isSubstring(struct data_t stringVal)
{
char substring[] = "New York";
int M = sizeof(substring);
int N = sizeof(stringVal.buf) - 1;
/* A loop to slide pat[] one by one */
for (int i = 0; i <= N - M; i++) {
int j;
/* For current index i, check for
pattern match */
for (j = 0; j < M; j++)
if (stringVal.buf[i + j] != substring[j])
break;
if (j == M)
return true;
}
return false;
}
int Test(void *ctx)
{
#pragma clang loop unroll(full)
for (int i = 0; i < ARRAYSIZE; i++) {
int k = i;
struct data_t *line = lookupTable.lookup(&k);
if (line) {
// bpf_trace_printk("%s\n", key->buf);
if (isSubstring(*line)) {
bpf_trace_printk("%s\n", line->buf);
}
}
}
return 0;
}
My python code here:
import ctypes
from bcc import BPF
b = BPF(src_file="hello.c")
lookupTable = b["lookupTable"]
#add hello.csv to the lookupTable array
f = open("hello.csv","r")
contents = f.readlines()
for i in range(0,len(contents)):
string = contents[i].encode('utf-8')
print(len(string))
lookupTable[ctypes.c_int(i)] = ctypes.create_string_buffer(string, len(string))
f.close()
b.attach_kprobe(event=b.get_syscall_fnname("clone"), fn_name="Test")
b.trace_print()
Edit: Forgot to add the error: It's really long and can be found here: https://pastebin.com/a7E9L230
I think the most interesting part of the error is near the bottom where it mentions:
The sequence of 8193 jumps is too complex.
And a little bit farther down mentions: Bad Address.
The verifier checks all branches in your program. Each time it sees a jump instruction, it pushes the new branch to its “stack of branches to check”. This stack has a limit (BPF_COMPLEXITY_LIMIT_JMP_SEQ, currently 8192) that you are hitting, as the verifier tells you. “Bad Address” is just the translation of kernel's errno value which is set to -EFAULT in that case.
Not sure how to fix it though, you could try:
With smaller strings, or
On a 5.3+ kernel (which supports bounded loops): without unrolling the loop with clang (I don't know if it would help).
I want to have my Zedboard return a numeric value using the Xilinx lwIP example as a base but no matter what I do I can't figure out what stores the data received or transmitted.
I have found the void type payload but I don't know what to do with it.
Snapshot of one instance of payload and a list of lwIP files
Below is the closest function to my goal:
err_t recv_callback(void *arg, struct tcp_pcb *tpcb,
struct pbuf *p, err_t err){
/* do not read the packet if we are not in ESTABLISHED state */
if (!p) {
tcp_close(tpcb);
tcp_recv(tpcb, NULL);
return ERR_OK;
}
/* indicate that the packet has been received */
tcp_recved(tpcb, p->len);
/* echo back the payload */
/* in this case, we assume that the payload is < TCP_SND_BUF */
if (tcp_sndbuf(tpcb) > p->len) {
err = tcp_write(tpcb, p->payload, p->len, 1);
//I need to change p->paylod but IDK where it is given a value.
} else
xil_printf("no space in tcp_sndbuf\n\r");
/* free the received pbuf */
pbuf_free(p);
return ERR_OK;
}
Any guidance is appreciated.
Thanks,
Turtlemii
-I cheated and just made sure that the function has access to Global_tpcb from echo.c
-tcp_write() reads in an address and displays each char it seems.
void Print_Code()
{
/* Prepare for TRANSMISSION */
char header[] = "\rSwitch: 1 2 3 4 5 6 7 8\n\r"; //header text
char data_t[] = " \n\r\r"; //area for storing the
data
unsigned char mask = 10000000; //mask to decode switches
swc_value = XGpio_DiscreteRead(&SWCInst, 1); //Save switch values
/* Write switch values to the LEDs for visual. */
XGpio_DiscreteWrite(&LEDInst, LED_CHANNEL, swc_value);
for (int i =0; i<=7; i++) //load data_t with switch values (0/1)
{
data_t[8+2*i] = '0' + ((swc_value & mask)/mask); //convert one bit to 0/1
mask = mask >> 1;//move to next bit
}
int len_header = *(&header + 1) - header; //find the length of the
header string
int len_data = *(&data_t + 1) - data_t; //find the length of the data string
tcp_write(Global_tpcb, &header, len_header, 1); //print the header
tcp_write(Global_tpcb, &data_t, len_data, 1); //print the data
}
I am working in C with Netbeans8.0
I have to read files in an iterative approach to get list of words. That is, in single iteration a file is read into an array of strings and then merge this array into a single array.
void merge_array(char** a,int* M, char** b,int N)
{
//............. Add extra memory to a ..............*/
void *tmp = realloc(a, (*M+N) * sizeof(*a));
if (tmp == NULL)
{
perror("Merging -> Could not reallocate");
exit(EXIT_FAILURE);
}
a = tmp;
memset(a+(*M), 0, N*sizeof(*a));
//............. copy strings in b to a ..............*/
int i,j=0;
for(i=*M; i<((*M)+N); i++)
{
size_t wlen = strlen(b[j]);
a[i] = malloc((wlen+1) * sizeof(char));
if (a[i] == NULL)
{
perror("Failed to replicate string");
exit(EXIT_FAILURE);
}
memcpy(a[i], b[j], wlen+1);
j++;
}
(*M) = (*M)+N; // resetting the count
printf("Confirm - %s, %d\n",a[0],*M);
}
Above function reads the contents of a file. In main above function is called iteratively and merged into a single array named 'termlist'. Main code is given below
char** termlist;
int termCount=0;
while(files[i]){
char **word_array;
int wdCnt,a;
char* tmp = (char*) malloc(strlen(path)*sizeof(char));
strcpy(tmp,path); strcat(tmp,files[i]); strcpy(files[i],tmp);
printf("\n\n******* Reading file %s...\n",files[i]);
word_array = getTerms_fscanf(files[i],&a); //reading contents of file
wdCnt = a;
if(i==0) // before reading the first file initializing the termlist
{
termlist = (char**) malloc(wdCnt*sizeof(char*));
}
merge_array(termlist,&termCount,word_array,wdCnt);
printf("CHECK - %s, %d\n",termlist[0],termCount);
free(word_array);
++i;
}
Now the problem is that,
After 1st two iterations, Inside function everything works fine but in main values of termlist[0], termlist[1] turns out to be junk.. That is first 2 words read from first file is lost. The 3rd iteration returns with failure at merge_array function call.
Output is
******* Reading F:/Netbeans C/Test Docs/doc1.txt...
Confirm - tour, 52
CHECK - tour, 52
******* Reading F:/Netbeans C/Test Docs/doc2.txt...
Confirm - tour, 71
CHECK - Ôk'aÔk'a`œ€`œ€äk'aäk'aìk'aìk'aôk'aôk'aük'aük'ah“€, 71
I am not able to identify problem with this.. Please help with this..