linux-kernel - [PATCH 4.6 023/121] MIPS: Fix sigreturn via VDSO on microMIPS kernel

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Date:	Sun,  5 Jun 2016 14:42:55 -0700
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	linux-kernel@...r.kernel.org
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	stable@...r.kernel.org, James Hogan <james.hogan@...tec.com>,
	Paul Burton <paul.burton@...tec.com>,
	linux-mips@...ux-mips.org, Ralf Baechle <ralf@...ux-mips.org>
Subject: [PATCH 4.6 023/121] MIPS: Fix sigreturn via VDSO on microMIPS kernel

4.6-stable review patch.  If anyone has any objections, please let me know.

------------------

From: James Hogan <james.hogan@...tec.com>

commit 13eb192d10bcc9ac518d57356179071d603bcb4e upstream.

In microMIPS kernels, handle_signal() sets the isa16 mode bit in the
vdso address so that the sigreturn trampolines (which are offset from
the VDSO) get executed as microMIPS.

However commit ebb5e78cc634 ("MIPS: Initial implementation of a VDSO")
changed the offsets to come from the VDSO image, which already have the
isa16 mode bit set correctly since they're extracted from the VDSO
shared library symbol table.

Drop the isa16 mode bit handling from handle_signal() to fix sigreturn
for cores which support both microMIPS and normal MIPS. This doesn't fix
microMIPS only cores, since the VDSO is still built for normal MIPS, but
thats a separate problem.

Fixes: ebb5e78cc634 ("MIPS: Initial implementation of a VDSO")
Signed-off-by: James Hogan <james.hogan@...tec.com>
Cc: Paul Burton <paul.burton@...tec.com>
Cc: linux-mips@...ux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/13348/
Signed-off-by: Ralf Baechle <ralf@...ux-mips.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 arch/mips/kernel/signal.c |    8 --------
 1 file changed, 8 deletions(-)

--- a/arch/mips/kernel/signal.c
+++ b/arch/mips/kernel/signal.c
@@ -770,15 +770,7 @@ static void handle_signal(struct ksignal
 	sigset_t *oldset = sigmask_to_save();
 	int ret;
 	struct mips_abi *abi = current->thread.abi;
-#ifdef CONFIG_CPU_MICROMIPS
-	void *vdso;
-	unsigned long tmp = (unsigned long)current->mm->context.vdso;
-
-	set_isa16_mode(tmp);
-	vdso = (void *)tmp;
-#else
 	void *vdso = current->mm->context.vdso;
-#endif

 	if (regs->regs[0]) {
 		switch(regs->regs[2]) {