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authorNathan Lynch <nathan_lynch@mentor.com>2014-11-10 23:46:27 +0100
committerRussell King <rmk+kernel@arm.linux.org.uk>2014-11-13 23:45:21 +0000
commit08b964ff3c51b10aaf2e6ba639f40054c09f0f7a (patch)
tree5d688cd847dcdfddc7ad0ab0f28c1f74f1f3fd83
parent238962ac71910d6c20162ea5230685fead1836a4 (diff)
ARM: 8198/1: make kuser helpers depend on MMU
The kuser helpers page is not set up on non-MMU systems, so it does not make sense to allow CONFIG_KUSER_HELPERS to be enabled when CONFIG_MMU=n. Allowing it to be set on !MMU results in an oops in set_tls (used in execve and the arm_syscall trap handler): Unhandled exception: IPSR = 00000005 LR = fffffff1 CPU: 0 PID: 1 Comm: swapper Not tainted 3.18.0-rc1-00041-ga30465a #216 task: 8b838000 ti: 8b82a000 task.ti: 8b82a000 PC is at flush_thread+0x32/0x40 LR is at flush_thread+0x21/0x40 pc : [<8f00157a>] lr : [<8f001569>] psr: 4100000b sp : 8b82be20 ip : 00000000 fp : 8b83c000 r10: 00000001 r9 : 88018c84 r8 : 8bb85000 r7 : 8b838000 r6 : 00000000 r5 : 8bb77400 r4 : 8b82a000 r3 : ffff0ff0 r2 : 8b82a000 r1 : 00000000 r0 : 88020354 xPSR: 4100000b CPU: 0 PID: 1 Comm: swapper Not tainted 3.18.0-rc1-00041-ga30465a #216 [<8f002bc1>] (unwind_backtrace) from [<8f002033>] (show_stack+0xb/0xc) [<8f002033>] (show_stack) from [<8f00265b>] (__invalid_entry+0x4b/0x4c) As best I can tell this issue existed for the set_tls ARM syscall before commit fbfb872f5f41 "ARM: 8148/1: flush TLS and thumbee register state during exec" consolidated the TLS manipulation code into the set_tls helper function, but now that we're using it to flush register state during execve, !MMU users encounter the oops at the first exec. Prevent CONFIG_MMU=n configurations from enabling CONFIG_KUSER_HELPERS. Fixes: fbfb872f5f41 (ARM: 8148/1: flush TLS and thumbee register state during exec) Signed-off-by: Nathan Lynch <nathan_lynch@mentor.com> Reported-by: Stefan Agner <stefan@agner.ch> Acked-by: Uwe Kleine-K├Ânig <u.kleine-koenig@pengutronix.de> Cc: stable@vger.kernel.org Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
-rw-r--r--arch/arm/mm/Kconfig1
1 files changed, 1 insertions, 0 deletions
diff --git a/arch/arm/mm/Kconfig b/arch/arm/mm/Kconfig
index ae69809a9e47..7eb94e6fc376 100644
--- a/arch/arm/mm/Kconfig
+++ b/arch/arm/mm/Kconfig
@@ -798,6 +798,7 @@ config NEED_KUSER_HELPERS
config KUSER_HELPERS
bool "Enable kuser helpers in vector page" if !NEED_KUSER_HELPERS
+ depends on MMU
default y
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