I've been trying to get a watchpoint to trigger, but no luck.
There should be 4 watchpoints accordíng to DBGDIDR, DBGDSCR=0x0204000e, so there shouldn't be any problems there?
I use (just in case) the cp14 interface - write DBGWVR0 and DBGWCR0 and read them back to see that the values went there.
Then I access the memory location, but nothing happens. Oh, and there are no masks in the CPSR set.
The program runs in non-secure SVC-mode.
Here's the watchpoint setting code:
void rpi2_set_watchpoint(unsigned int num, unsigned int addr, unsigned int control) { char scratchpad[9]; SYNC; volatile uint32_t *pval; pval = (volatile uint32_t *)(dbg_reg_base + 0x088); #if 0 // if memory-mapped interface works // 96-111 0x180-0x1BC DBGWVRm 4 watchpoint values // 112-127 0x1C0-0x1FC DBGWCRm 4 watchpoint controls uint32_t *pval, *pctrl; pval = (volatile uint32_t *)(dbg_reg_base + 0x180); pctrl = (volatile uint32_t *)(dbg_reg_base + 0x1c0); pval[num] = (uint32_t)addr; pctrl[num] = control; #else // have to use cp14 switch (num) { case 0: serial_raw_puts("\r\nwatch0!\r\n"); // write to DBGWVR0 asm volatile ("mcr p14, 0, %[val], c0, c0, 6\n\t" ::[val] "r" (addr) :); // write to DBGWCR0 asm volatile ("mcr p14, 0, %[ctl], c0, c0, 7\n\t" ::[ctl] "r" (control) :); // debug asm volatile ("mrc p14, 0, %[val], c0, c0, 6\n\t" :[val] "=r" (addr) ::); asm volatile ("mrc p14, 0, %[ctl], c0, c0, 7\n\t" :[ctl] "=r" (control) ::); serial_raw_puts("DBGWVR0: "); util_word_to_hex(scratchpad, addr); serial_raw_puts(scratchpad); serial_raw_puts(" DBGWCR0: "); util_word_to_hex(scratchpad, control); serial_raw_puts(scratchpad); serial_raw_puts(" DBGDSCR: "); util_word_to_hex(scratchpad, *pval); serial_raw_puts(scratchpad); serial_raw_puts("\r\n"); break; case 1: serial_raw_puts("\r\nwatch1!\r\n"); // write to DBGWVR1 asm volatile ("mcr p14, 0, %[val], c0, c1, 6\n\t" ::[val] "r" (addr) :); // write to DBGWCR1 asm volatile ("mcr p14, 0, %[ctl], c0, c1, 7\n\t" ::[ctl] "r" (control) :); break; case 2: serial_raw_puts("\r\nwatch2!\r\n"); // write to DBGWVR2 asm volatile ("mcr p14, 0, %[val], c0, c2, 6\n\t" ::[val] "r" (addr) :); // write to DBGWCR2 asm volatile ("mcr p14, 0, %[ctl], c0, c2, 7\n\t" ::[ctl] "r" (control) :); break; case 3: serial_raw_puts("\r\nwatch3!\r\n"); // write to DBGWVR3 asm volatile ("mcr p14, 0, %[val], c0, c3, 6\n\t" ::[val] "r" (addr) :); // write to DBGWCR3 asm volatile ("mcr p14, 0, %[ctl], c0, c3, 7\n\t" ::[ctl] "r" (control) :); break; default: serial_raw_puts("\r\nwatch?!\r\n"); // do nothing; break; } #endif SYNC; }
The machine is Raspberry Pi 2B if that helps.
The output from the function (through dgb):
w \x00](gdb) watch g_testloc
Sending packet: $m8360,4#9e...[\x00][\x00][\x00][\x00][\x00][\x00][\x00][\x00][\x00][\x00][\x00][
r +]Ack
[$][7][0][8][3][0][0][0][0][#][9][2]Packet received: 70830000
[
w \x00]Sending packet: $m8360,4#9e...[\x00][\x00][\x00][\x00][\x00][\x00][\x00][\x00][\x00][\x00][\x00][
w \x00]Hardware watchpoint 1: g_testloc
(gdb) cont
Continuing.
w \x00]Sending packet: $Z2,8360,4#e9...[\x00][\x00][\x00][\x00][\x00][\x00][\x00][\x00][\x00][\x00][\x00][\x00][\x00][
[\r][\n][w][a][t][c][h][ ][n][u][m][=][ ][0][0][0][0][0][0][0][0][ ][v][a][l][=][0][0][0][0][8][3][6][0][ ][c][t][r][l][0][0][0][0][2][1][f][7][\r][\n][\r][\n][w][a][t][c][h][0][!][\r][\n][D][B][G][W][V][R][0][:][ ][0][0][0][0][8][3][6][0][ ][D][B][G][W][C][R][0][:][ ][0][0][0][0][2][1][f][7][ ][D][B][G][D][S][C][R][:][ ][0][2][0][4][0][0][0][e][\r][\n][$][O][K][#][9][a]Packet received: OK
w \x00]Packet Z2 (write-watchpoint) is supported
Sending packet: $vCont?#49...[\x00][\x00][\x00][\x00][\x00][\x00][\x00][\x00][\x00][\x00][
[$][#][0][0]Packet received:
The address of g_testloc is indeed 0x8360
Disassembly of section .bss:
00008360 <g_testloc>:
8360: 00000000 andeq r0, r0, r0
False alarm: DBGAUTHSTATUS = 0xff.
DBGEN is high and invasive and non-invasibe secure and non-secure debug is enabled.
So what the heck is wrong?
The problem is solved. It was the OS lock.
Both double lock and dbg lock were clear.