path: root/arch/um/sys-i386
diff options
authorIngo van Lil <inguin@gmx.de>2011-09-14 16:21:23 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2011-09-14 18:09:37 -0700
commitfbfe9c847edf57ac8232aeafb290f272289893a3 (patch)
treeda25f3f4ece74b9fa328ce3884f19ff18eff516d /arch/um/sys-i386
parentb40997b872cdb70140f127af6069f00a86b6cf81 (diff)
um: Save FPU registers between task switches
Some time ago Jeff prepared 42daba316557 ("uml: stop saving process FP state") for UML to stop saving the process FP state between task switches. The assumption was that since with SKAS0 every guest process runs inside a host process context the host OS will take care of keeping the proper FP state. Unfortunately this is not true for multi-threaded applications, where all guest threads share a single host process context yet all may use the FPU on their own. Although I haven't verified it I suspect things to be even worse in SKAS3 mode where all guest processes run inside a single host process. The patch reintroduces the saving and restoring of the FP context between task switches. [richard@nod.at: Ingo posted this patch in 2009, sadly it was never applied and got lost. Now in 2011 the problem was reported by Gunnar.] Signed-off-by: Ingo van Lil <inguin@gmx.de> Signed-off-by: Richard Weinberger <richard@nod.at> Reported-by: <gunnarlindroth@hotmail.com> Tested-by: <gunnarlindroth@hotmail.com> Cc: Stanislav Meduna <stano@meduna.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'arch/um/sys-i386')
1 files changed, 1 insertions, 0 deletions
diff --git a/arch/um/sys-i386/shared/sysdep/ptrace.h b/arch/um/sys-i386/shared/sysdep/ptrace.h
index d50e62e07070..c398a5076111 100644
--- a/arch/um/sys-i386/shared/sysdep/ptrace.h
+++ b/arch/um/sys-i386/shared/sysdep/ptrace.h
@@ -53,6 +53,7 @@ extern int sysemu_supported;
struct uml_pt_regs {
unsigned long gp[MAX_REG_NR];
+ unsigned long fp[HOST_FPX_SIZE];
struct faultinfo faultinfo;
long syscall;
int is_user;

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