MIPS: Skip odd double FP registers when copying FP32 sigcontext

When a task uses 32 bit floating point, the odd indexed 32b register
values are stored in bits 63:32 of the preceding even indexed 64b
FP register field in saved context. Thus there is no point in
preserving the odd indexed 64b register fields since they hold no
valid context. This patch will cause them to be skipped, as is
already done in arch/mips/kernel/signal32.c.

[[email protected]: Fixed reject.]

Signed-off-by: Paul Burton <[email protected]>
Cc: [email protected]
Cc: Guenter Roeck <[email protected]>
Cc: Matthew Fortune <[email protected]>
Cc: Michael Ellerman <[email protected]>
Cc: [email protected]
Cc: Richard Weinberger <[email protected]>
Cc: Andy Lutomirski <[email protected]>
Cc: Maciej W. Rozycki <[email protected]>
Cc: Andrew Morton <[email protected]>
Patchwork: https://patchwork.linux-mips.org/patch/10791/
Signed-off-by: Ralf Baechle <[email protected]>

1 files changed, 4 insertions, 2 deletions

diff --git a/arch/mips/kernel/signal.c b/arch/mips/kernel/signal.c
index 9c42c500134e..cc3a01f5c5af 100644
--- a/arch/mips/kernel/signal.c
+++ b/arch/mips/kernel/signal.c
@@ -69,8 +69,9 @@ static int copy_fp_to_sigcontext(void __user *sc)
 	uint32_t __user *csr = sc + abi->off_sc_fpc_csr;
 	int i;
 	int err = 0;
+	int inc = test_thread_flag(TIF_32BIT_FPREGS) ? 2 : 1;
 
-	for (i = 0; i < NUM_FPU_REGS; i++) {
+	for (i = 0; i < NUM_FPU_REGS; i += inc) {
 		err |=
 		    __put_user(get_fpr64(&current->thread.fpu.fpr[i], 0),
 			       &fpregs[i]);
@@ -87,9 +88,10 @@ static int copy_fp_from_sigcontext(void __user *sc)
 	uint32_t __user *csr = sc + abi->off_sc_fpc_csr;
 	int i;
 	int err = 0;
+	int inc = test_thread_flag(TIF_32BIT_FPREGS) ? 2 : 1;
 	u64 fpr_val;
 
-	for (i = 0; i < NUM_FPU_REGS; i++) {
+	for (i = 0; i < NUM_FPU_REGS; i += inc) {
 		err |= __get_user(fpr_val, &fpregs[i]);
 		set_fpr64(&current->thread.fpu.fpr[i], 0, fpr_val);
 	}