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authorTim Bird <tim.bird@am.sony.com>2012-05-02 22:55:39 +0100
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2012-05-12 09:32:05 -0700
commitacfee6ae4cf54e4afb10252c86dc72ca3472eec7 (patch)
parent15e8eae4f13da852c0ed0a8b85af5ba62c46a56b (diff)
ARM: 7410/1: Add extra clobber registers for assembly in kernel_execve
commit e787ec1376e862fcea1bfd523feb7c5fb43ecdb9 upstream. The inline assembly in kernel_execve() uses r8 and r9. Since this code sequence does not return, it usually doesn't matter if the register clobber list is accurate. However, I saw a case where a particular version of gcc used r8 as an intermediate for the value eventually passed to r9. Because r8 is used in the inline assembly, and not mentioned in the clobber list, r9 was set to an incorrect value. This resulted in a kernel panic on execution of the first user-space program in the system. r9 is used in ret_to_user as the thread_info pointer, and if it's wrong, bad things happen. Signed-off-by: Tim Bird <tim.bird@am.sony.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
1 files changed, 1 insertions, 1 deletions
diff --git a/arch/arm/kernel/sys_arm.c b/arch/arm/kernel/sys_arm.c
index d2b177905cdb..76cbb055dd05 100644
--- a/arch/arm/kernel/sys_arm.c
+++ b/arch/arm/kernel/sys_arm.c
@@ -115,7 +115,7 @@ int kernel_execve(const char *filename,
"Ir" (THREAD_START_SP - sizeof(regs)),
"r" (&regs),
"Ir" (sizeof(regs))
- : "r0", "r1", "r2", "r3", "ip", "lr", "memory");
+ : "r0", "r1", "r2", "r3", "r8", "r9", "ip", "lr", "memory");
return ret;