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| author | Aleksandar Markovic <aleksandar.markovic@imgtec.com> | 2017-08-21 14:24:47 +0200 |
|---|---|---|
| committer | Ralf Baechle <ralf@linux-mips.org> | 2017-08-29 15:21:56 +0200 |
| commit | 1ff8560ac9db1cbffcd700b70e1661f2fcc2e5d7 (patch) | |
| tree | 0a42550ba42a4e94f9ae8b9e8bd5e07816086699 /arch/mips | |
| parent | MIPS: math-emu: <MADDF|MSUBF>.D: Fix accuracy (64-bit case) (diff) | |
| download | linux-1ff8560ac9db1cbffcd700b70e1661f2fcc2e5d7.tar.xz linux-1ff8560ac9db1cbffcd700b70e1661f2fcc2e5d7.zip | |
MIPS: math-emu: CMP.Sxxx.<D|S>: Prevent occurrences of SIGILL crashes
Fix CMP.Sxxx.<D|S> SIGILL crashes by fixing main switch/case statement
in fpu_emul() function so that inadvertent fall-troughs are prevented.
Consider, let's say, CMP.SAF.S instruction when one of inputs is zero
and another input is a signaling NaN. The desired output is zero, and
the exception flag "invalid operation" set. For such case, the main
portion of the implementation is within "d_fmt" case of the main
"switch/case" statement in fpu_emul() function. The execution will
follow one of "if-else" branches that doesn't contain "goto cop1scr;"
statement, and will therefore reach the end of "d_fmt" case. It will
subsequently fall through to the next case, "l_fmt". After following
similar pattern, the execution will fall through to the succeeding
case, which is "default". The "default" case contains "return SIGILL;"
statement only. This means that the caller application will crash
with "illegal instruction" message.
It is obvious that above described fall-throughs are unnecessary and
harmful. This patch rectifies that behavior by providing "break;"
statements at the end of cases "d_fmt" and "l_fmt".
There are 22 instructions affected by this problem:
CMP.<SAF|SEQ|SLE|SLT|SNE|SOR|SUEQ|SULE|SULT|SUN|SUNE>.<D|S>.
Signed-off-by: Miodrag Dinic <miodrag.dinic@imgtec.com>
Signed-off-by: Goran Ferenc <goran.ferenc@imgtec.com>
Signed-off-by: Aleksandar Markovic <aleksandar.markovic@imgtec.com>
Cc: Douglas Leung <douglas.leung@imgtec.com>
Cc: James Hogan <james.hogan@imgtec.com>
Cc: Maciej W. Rozycki <macro@imgtec.com>
Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: Paul Burton <paul.burton@imgtec.com>
Cc: Petar Jovanovic <petar.jovanovic@imgtec.com>
Cc: Raghu Gandham <raghu.gandham@imgtec.com>
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/17140/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Diffstat (limited to 'arch/mips')
| -rw-r--r-- | arch/mips/math-emu/cp1emu.c | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/arch/mips/math-emu/cp1emu.c b/arch/mips/math-emu/cp1emu.c index d225e2173899..9694e9e0b14c 100644 --- a/arch/mips/math-emu/cp1emu.c +++ b/arch/mips/math-emu/cp1emu.c @@ -2394,6 +2394,7 @@ dcopuop: break; } } + break; } case l_fmt: @@ -2468,6 +2469,8 @@ dcopuop: break; } } + break; + default: return SIGILL; } |