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authorPaul Burton <paul.burton@imgtec.com>2015-01-08 12:17:37 +0000
committerRalf Baechle <ralf@linux-mips.org>2015-02-12 12:30:29 +0100
commit9791554b45a2acc28247f66a5fd5bbc212a6b8c8 (patch)
treeb23e43745d5b5f10b004dcbe216b5a02ad6018ec /kernel/sys.c
parentae58d882bfd3e537b1ed4a4c3577ca9ba853f0d8 (diff)
MIPS,prctl: add PR_[GS]ET_FP_MODE prctl options for MIPS
Userland code may be built using an ABI which permits linking to objects that have more restrictive floating point requirements. For example, userland code may be built to target the O32 FPXX ABI. Such code may be linked with other FPXX code, or code built for either one of the more restrictive FP32 or FP64. When linking with more restrictive code, the overall requirement of the process becomes that of the more restrictive code. The kernel has no way to know in advance which mode the process will need to be executed in, and indeed it may need to change during execution. The dynamic loader is the only code which will know the overall required mode, and so it needs to have a means to instruct the kernel to switch the FP mode of the process. This patch introduces 2 new options to the prctl syscall which provide such a capability. The FP mode of the process is represented as a simple bitmask combining a number of mode bits mirroring those present in the hardware. Userland can either retrieve the current FP mode of the process: mode = prctl(PR_GET_FP_MODE); or modify the current FP mode of the process: err = prctl(PR_SET_FP_MODE, new_mode); Signed-off-by: Paul Burton <paul.burton@imgtec.com> Cc: Matthew Fortune <matthew.fortune@imgtec.com> Cc: Markos Chandras <markos.chandras@imgtec.com> Cc: linux-mips@linux-mips.org Patchwork: https://patchwork.linux-mips.org/patch/8899/ Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Diffstat (limited to 'kernel/sys.c')
-rw-r--r--kernel/sys.c12
1 files changed, 12 insertions, 0 deletions
diff --git a/kernel/sys.c b/kernel/sys.c
index a8c9f5a7dda6..08b16bbdcdf0 100644
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -97,6 +97,12 @@
#ifndef MPX_DISABLE_MANAGEMENT
# define MPX_DISABLE_MANAGEMENT(a) (-EINVAL)
#endif
+#ifndef GET_FP_MODE
+# define GET_FP_MODE(a) (-EINVAL)
+#endif
+#ifndef SET_FP_MODE
+# define SET_FP_MODE(a,b) (-EINVAL)
+#endif
/*
* this is where the system-wide overflow UID and GID are defined, for
@@ -2215,6 +2221,12 @@ SYSCALL_DEFINE5(prctl, int, option, unsigned long, arg2, unsigned long, arg3,
case PR_MPX_DISABLE_MANAGEMENT:
error = MPX_DISABLE_MANAGEMENT(me);
break;
+ case PR_SET_FP_MODE:
+ error = SET_FP_MODE(me, arg2);
+ break;
+ case PR_GET_FP_MODE:
+ error = GET_FP_MODE(me);
+ break;
default:
error = -EINVAL;
break;