Re: [PATCH 8/9] Support TLS variables on FreeBSD/riscv.

Andrew Burgess
2019-01-27T23:35:36Z

* John Baldwin <jhb@FreeBSD.org> [2019-01-22 10:43:01 -0800]:

> Derive the pointer to the DTV array from the tp register.
>
> gdb/ChangeLog:
>
> * riscv-fbsd-tdep.c (riscv_fbsd_get_thread_local_address): New.
> (riscv_fbsd_init_abi): Install gdbarch
> "fetch_tls_load_module_address" and "get_thread_local_address"
> methods.
> ---
> gdb/ChangeLog | 7 +++++++
> gdb/riscv-fbsd-tdep.c | 27 +++++++++++++++++++++++++++
> 2 files changed, 34 insertions(+)

These look good to me.

Thanks,
Andrew

>
> diff --git a/gdb/ChangeLog b/gdb/ChangeLog
> index 06c637c80a..5d228614db 100644
> --- a/gdb/ChangeLog
> +++ b/gdb/ChangeLog
> @@ -1,3 +1,10 @@
> +2019-01-22 John Baldwin <jhb@FreeBSD.org>
> +
> + * riscv-fbsd-tdep.c (riscv_fbsd_get_thread_local_address): New.
> + (riscv_fbsd_init_abi): Install gdbarch
> + "fetch_tls_load_module_address" and "get_thread_local_address"
> + methods.
> +
> 2019-01-22 John Baldwin <jhb@FreeBSD.org>
>
> * i386-fbsd-tdep.c (i386fbsd_get_thread_local_address): New.
> diff --git a/gdb/riscv-fbsd-tdep.c b/gdb/riscv-fbsd-tdep.c
> index 97ad28f59a..3125a2285e 100644
> --- a/gdb/riscv-fbsd-tdep.c
> +++ b/gdb/riscv-fbsd-tdep.c
> @@ -174,6 +174,28 @@ static const struct tramp_frame riscv_fbsd_sigframe =
> riscv_fbsd_sigframe_init
> };
>
> +/* Implement the "get_thread_local_address" gdbarch method. */
> +
> +static CORE_ADDR
> +riscv_fbsd_get_thread_local_address (struct gdbarch *gdbarch, ptid_t ptid,
> + CORE_ADDR lm_addr, CORE_ADDR offset)
> +{
> + struct regcache *regcache;
> +
> + regcache = get_thread_arch_regcache (ptid, gdbarch);
> +
> + target_fetch_registers (regcache, RISCV_TP_REGNUM);
> +
> + ULONGEST tp;
> + if (regcache->cooked_read (RISCV_TP_REGNUM, &tp) != REG_VALID)
> + error (_("Unable to fetch %%tp"));
> +
> + /* %tp points to the end of the TCB which contains two pointers.
> + The first pointer in the TCB points to the DTV array. */
> + CORE_ADDR dtv_addr = tp - (gdbarch_ptr_bit (gdbarch) / 8) * 2;
> + return fbsd_get_thread_local_address (gdbarch, dtv_addr, lm_addr, offset);
> +}
> +
> /* Implement the 'init_osabi' method of struct gdb_osabi_handler. */
>
> static void
> @@ -193,6 +215,11 @@ riscv_fbsd_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
>
> set_gdbarch_iterate_over_regset_sections
> (gdbarch, riscv_fbsd_iterate_over_regset_sections);
> +
> + set_gdbarch_fetch_tls_load_module_address (gdbarch,
> + svr4_fetch_objfile_link_map);
> + set_gdbarch_get_thread_local_address (gdbarch,
> + riscv_fbsd_get_thread_local_address);
> }
>
> void
> --
> 2.19.2
>