[#7702] GDB fails to find prologue

Question

Accepted Answer

[#7702] GDB fails to find prologue

Submitted By: Stuart Henderson

Open Date

2013-03-13 06:13:39

Priority:

Medium High Assignee:

Nobody

Board:

N/A Silicon Revision:

Resolution:

N/A Fixed In Release:

N/A

Processor:

ALL

Host Operating System:

toolchain rev.:

kernel rev.:

State:

Open Found In Release:

2012R2

Is this bug repeatable?:

N/A

Summary: GDB fails to find prologue

Details:

In the, somewhat rare, example we have below, gdb will completely fail to set a breakpoint anywhere sensible. in the end it sets it off in bad memory. this is due to the prologue skipping code in GDB (gdb/bfin-tdep.c:bfin_skip_prologue()).

At this point I tried making the function a little bigger with NOPs, to push us over the UPPER_LIMIT, but this ended up creating a breakpoint at 0xffa00002 (pc = orig_pc + 2;), in the middle of an instruction.

This is causing some issues with Eclipse's default behaviour.

None of these issues are particularly huge, but I think they warrant a review of the prologue skipping code.

(gdb) x/10i $pc

0xffa00000 <new>: P0.H = 0xffc0; /* (-64) P0=0x0xffc00000(-4194304) */

0xffa00004 <new+4>: P1.H = 0xffe0; /* (-32) P1=0x0xffe00000(-2097152) */

0xffa00008 <new+8>: P0.L = 0x0; /* ( 0) P0=0x0xffc00000(-4194304) */

0xffa0000c <new+12>: R0.L = 0x800; /* (2048) R0=0x0x800(2048) */

0xffa00010 <new+16>: W[P0] = R0;

0xffa00012 <new+18>: SSYNC;

0xffa00014 <new+20>: P0.L = 0x4; /* ( 4) P0=0x0xffc00004(-4194300) */

0xffa00018 <new+24>: R0.L = 0x2; /* ( 2) R0=0x0x2( 2) */

0xffa0001c <new+28>: W[P0] = R0;

0xffa0001e <new+30>: SSYNC;

0xffa00020: NOP;

0xffa00022: JUMP.S 0x0xffa00000 <new>;

0xffa00024: RTS;

0xffa00026: NOP;

0xffa00028: I0.L = 0x1300; /* (4864) I0=0x0x1300(4864) */

0xffa0002c: I0.H = 0xffe0; /* (-32) I0=0x0xffe01300(-2092288) */

0xffa00030: I1.L = 0x300; /* (768) I1=0x0x300(768) */

0xffa00034: I1.H = 0xffe0; /* (-32) I1=0x0xffe00300(-2096384) */

0xffa00038: R7 = 0x0 (X); /* R7=0x0( 0) */

0xffa0003a: [I0] = R7;

(gdb) break new

Breakpoint 1 at 0xffa00024: file test.S, line 16.

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