thread support broken on ppc-aix

Programming / Debugging / GDB - Joel Brobecker [gnat.com] - 29 August 2013 16:02 UTC

Thread support got broken when adding 64bit support on ppc-aix. Upon digging further, I found that the following patch...

| * gdb_ptrace.h: Use ptrace64 instead of ptrace if HAVE_PTRACE64 | is defined. | * rs6000-nat.c: Check for __ld_info64_ if compiling 64 BIT gdb. | (rs6000_ptrace32): Call ptrace64 instead of ptrace if present. | (rs6000_ptrace64): Call ptace64 instead of ptracex if present. | * configure.ac: Check for ptrace64. | * configure, config.in: Regenerate.

... is responsible for this regression:

(gdb) x /x &__n_pthreads 0xf06a8258 <__n_pthreads>: Cannot access memory at address 0xf06a8258

Prior to the patch, we have:

(gdb) x /x &__n_pthreads 0xf06a8258 <__n_pthreads>: 0x00000003

The problem occurs inside rs6000_ptrace32, while calling ptrace64. The address is given to rs6000_ptrace32 as an "int *", while ptrace64 takes a "long long". The cast causes the address to be sign-extended, which results in GDB trying to read the wrong address.

This patch fixes the issue by casting the address to a "uintptr_t" instead, and letting the compiler do the implicit conversion to "long long" in the function call.

gdb/ChangeLog:

- rs6000-nat.c (rs6000_ptrace32): Cast "addr" to "uintptr_t" instead of "long long" in call to ptrace64.

75d11e2 thread support broken on ppc-aix.
gdb/ChangeLog | 5 +++++
gdb/rs6000-nat.c | 2 +-
2 files changed, 6 insertions(+), 1 deletion(-)

Upstream: sourceware.org

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