MIPS: Avoid BUG warning in arch_check_elf

BugLink: http://bugs.launchpad.net/bugs/1688499
commit c46f59e90226fa5bfcc83650edebe84ae47d454b upstream.

arch_check_elf contains a usage of current_cpu_data that will call
smp_processor_id() with preemption enabled and therefore triggers a
"BUG: using smp_processor_id() in preemptible" warning when an fpxx
executable is loaded.

As a follow-up to commit b244614a60ab ("MIPS: Avoid a BUG warning during
prctl(PR_SET_FP_MODE, ...)"), apply the same fix to arch_check_elf by
using raw_current_cpu_data instead. The rationale quoted from the previous
commit:

"It is assumed throughout the kernel that if any CPU has an FPU, then
all CPUs would have an FPU as well, so it is safe to perform the check
with preemption enabled - change the code to use raw_ variant of the
check to avoid the warning."

Fixes: 46490b572544 ("MIPS: kernel: elf: Improve the overall ABI and FPU mode checks")
Signed-off-by: James Cowgill <James.Cowgill@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/15951/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>

diff --git a/arch/mips/kernel/elf.c b/arch/mips/kernel/elf.c
index 6430bff21fff80a7bb6647c6af0198364cac7bdd..5c429d70e17f6f24cbcfd0fa912c67eccd11f28f 100644 (file)
--- a/arch/mips/kernel/elf.c
+++ b/arch/mips/kernel/elf.c
@@ -257,7 +257,7 @@ int arch_check_elf(void *_ehdr, bool has_interpreter, void *_interp_ehdr,
        else if ((prog_req.fr1 && prog_req.frdefault) ||
                 (prog_req.single && !prog_req.frdefault))
                /* Make sure 64-bit MIPS III/IV/64R1 will not pick FR1 */
-               state->overall_fp_mode = ((current_cpu_data.fpu_id & MIPS_FPIR_F64) &&
+               state->overall_fp_mode = ((raw_current_cpu_data.fpu_id & MIPS_FPIR_F64) &&
                                          cpu_has_mips_r2_r6) ?
                                          FP_FR1 : FP_FR0;
        else if (prog_req.fr1)