[PATCH 3.16 072/192] MIPS: Send SIGILL for BPOSGE32 in `__compute_return_epc_for_insn'

Ben Hutchings
2017-10-09T13:44:46Z

From: "Maciej W. Rozycki" <macro@imgtec.com>

commit 7b82c1058ac1f8f8b9f2b8786b1f710a57a870a8 upstream.

Fix commit e50c0a8fa60d ("Support the MIPS32 / MIPS64 DSP ASE.") and
send SIGILL rather than SIGBUS whenever an unimplemented BPOSGE32 DSP
ASE instruction has been encountered in `__compute_return_epc_for_insn'
as our Reserved Instruction exception handler would in response to an
attempt to actually execute the instruction. Sending SIGBUS only makes
sense for the unaligned PC case, since moved to `__compute_return_epc'.
Adjust function documentation accordingly, correct formatting and use
`pr_info' rather than `printk' as the other exit path already does.

Fixes: e50c0a8fa60d ("Support the MIPS32 / MIPS64 DSP ASE.")
Signed-off-by: Maciej W. Rozycki <macro@imgtec.com>
Cc: James Hogan <james.hogan@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/16396/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
arch/mips/kernel/branch.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)

--- a/arch/mips/kernel/branch.c
+++ b/arch/mips/kernel/branch.c
@@ -396,7 +396,7 @@ int __MIPS16e_compute_return_epc(struct
*
* @regs: Pointer to pt_regs
* @insn: branch instruction to decode
- * @returns: -EFAULT on error and forces SIGBUS, and on success
+ * @returns: -EFAULT on error and forces SIGILL, and on success
* returns 0 or BRANCH_LIKELY_TAKEN as appropriate after
* evaluating the branch.
*/
@@ -633,8 +633,9 @@ int __compute_return_epc_for_insn(struct
return ret;

sigill:
- printk("%s: DSP branch but not DSP ASE - sending SIGBUS.\n", current->comm);
- force_sig(SIGBUS, current);
+ pr_info("%s: DSP branch but not DSP ASE - sending SIGILL.\n",
+ current->comm);
+ force_sig(SIGILL, current);
return -EFAULT;
}
EXPORT_SYMBOL_GPL(__compute_return_epc_for_insn);