diff options
| author | Paul Burton <paul.burton@imgtec.com> | 2017-06-02 11:35:01 -0700 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2017-06-26 07:13:11 +0200 |
| commit | c24159adf2226709053c48b3d536e756bf033e31 (patch) | |
| tree | d716d6a8f83a85f9aa4c2ca040b0b61764312785 | |
| parent | 94695386c79caccd82bf4048da642e6c9643fb92 (diff) | |
MIPS: Fix bnezc/jialc return address calculation
commit 1a73d9310e093fc3adffba4d0a67b9fab2ee3f63 upstream.
The code handling the pop76 opcode (ie. bnezc & jialc instructions) in
__compute_return_epc_for_insn() needs to set the value of $31 in the
jialc case, which is encoded with rs = 0. However its check to
differentiate bnezc (rs != 0) from jialc (rs = 0) was unfortunately
backwards, meaning that if we emulate a bnezc instruction we clobber $31
& if we emulate a jialc instruction it actually behaves like a jic
instruction.
Fix this by inverting the check of rs to match the way the instructions
are actually encoded.
Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Fixes: 28d6f93d201d ("MIPS: Emulate the new MIPS R6 BNEZC and JIALC instructions")
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/16178/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | arch/mips/kernel/branch.c | 4 |
1 files changed, 3 insertions, 1 deletions
diff --git a/arch/mips/kernel/branch.c b/arch/mips/kernel/branch.c index d8f9b357b222..e9fed8ca9b42 100644 --- a/arch/mips/kernel/branch.c +++ b/arch/mips/kernel/branch.c @@ -816,8 +816,10 @@ int __compute_return_epc_for_insn(struct pt_regs *regs, break; } /* Compact branch: BNEZC || JIALC */ - if (insn.i_format.rs) + if (!insn.i_format.rs) { + /* JIALC: set $31/ra */ regs->regs[31] = epc + 4; + } regs->cp0_epc += 8; break; #endif |