From: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Date: Mon, 16 Dec 2013 09:24:46 +0000 (+0100)
Subject: ARM: make isa_mode macro more robust and fix for v7-M
X-Git-Tag: v3.15-rc1~82^2^2~2^2~2
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=3f18b1bf599d3d13cd81fdf6bf869c458772adfe;p=pandora-kernel.git

ARM: make isa_mode macro more robust and fix for v7-M

The definition of isa_mode hardcodes the values to shift PSR_J_BIT and
PSR_T_BIT to move them to bits 1 and 0 respectively. Instead use __ffs to
calculate the shift from the #define already used for masking.

This is relevant on v7-M as there PSR_T_BIT is 0x01000000 instead of
0x00000020 for V7-[AR] and earlier. Because of that isa_mode produced
values >= 0x80000 which are unsuitable to index into isa_modes[4] there
and so made __show_regs read from undefined memory which resulted in
hangs and crashes.

Moreover isa_mode is wrong for v7-M even after this robustness fix as
there is no J-bit in the PSR register. So hardcode isa_mode to "Thumb"
for v7-M.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
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