On 9/19/22 13:43, Mark Brown wrote:
On Fri, Sep 16, 2022 at 01:01:31PM +0100, Catalin Marinas wrote:
On Mon, Aug 29, 2022 at 04:49:20PM +0100, Mark Brown wrote:
@@ -1392,7 +1407,7 @@ static const struct user_regset aarch64_regsets[] = {
},
[REGSET_TLS] = {
.core_note_type = NT_ARM_TLS,
- .n = 1,
+ .n = 2,
.size = sizeof(void *),
.align = sizeof(void *),
.regset_get = tls_get,
Does this change confuse user-space? I presume an updated gdb would
check the iov.len to figure out whether a new register is available but
would existing debuggers complain of the new size of this regset?
gdb seems happy as far as I can see, it is possible something would be
reusing the read_iov for repeated TLS read calls in a context where it
was only pointing at a single u64 but I'm not sure how realistic that
is given the idiom. I did do a search on sources.debian.net and didn't
turn up anything that'd have problems.
If using this as an extensiblility mechanism is a concern we need to
bear that in mind elsewhere, and for this it's either a case of
providing another single register regset or trying to do a generic
sysreg read/get (though that'd be another regset that's not idiomatic
for the regset API).
Older GDB's assume a single register for NT_ARM_TLS, so they will always
fetch TPIDR. Newer GDB's will check the size and act accordingly.
