The patch titled
x86_64: disable tsc with seccomp
has been removed from the -mm tree. Its filename is
x86_64-disable-tsc-with-seccomp.patch
This patch was probably dropped from -mm because
it has now been merged into a subsystem tree or
into Linus's tree, or because it was folded into
its parent patch in the -mm tree.
From: Andrea Arcangeli <andrea@xxxxxxxxxxxx>
akpm: needs new changelog.
akpm: I can't see the fuss really - context switch simply isn't as much a
fastpath as people think. If you're doing >10,000 switches/second/CPU then
you've got problems anyway.
Signed-off-by: Andrea Arcangeli <andrea@xxxxxxxxxxxx>
Cc: Andi Kleen <ak@xxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxx>
---
arch/x86_64/kernel/process.c | 29 +++++++++++++++++++++++++++++
include/linux/sched.h | 3 ++-
2 files changed, 31 insertions(+), 1 deletion(-)
diff -puN arch/x86_64/kernel/process.c~x86_64-disable-tsc-with-seccomp arch/x86_64/kernel/process.c
--- devel/arch/x86_64/kernel/process.c~x86_64-disable-tsc-with-seccomp 2006-04-22 01:39:32.000000000 -0700
+++ devel-akpm/arch/x86_64/kernel/process.c 2006-04-22 01:39:32.000000000 -0700
@@ -492,6 +492,33 @@ out:
}
/*
+ * This function selects if the context switch from prev to next
+ * has to tweak the TSC disable bit in the cr4.
+ */
+static inline void disable_tsc(struct task_struct *prev_p,
+ struct task_struct *next_p)
+{
+ struct thread_info *prev, *next;
+
+ /*
+ * gcc should eliminate the ->thread_info dereference if
+ * has_secure_computing returns 0 at compile time (SECCOMP=n).
+ */
+ prev = prev_p->thread_info;
+ next = next_p->thread_info;
+
+ if (has_secure_computing(prev) || has_secure_computing(next)) {
+ /* slow path here */
+ if (has_secure_computing(prev) &&
+ !has_secure_computing(next)) {
+ write_cr4(read_cr4() & ~X86_CR4_TSD);
+ } else if (!has_secure_computing(prev) &&
+ has_secure_computing(next))
+ write_cr4((read_cr4() | X86_CR4_TSD) & ~X86_CR4_PCE);
+ }
+}
+
+/*
* This special macro can be used to load a debugging register
*/
#define loaddebug(thread,r) set_debugreg(thread->debugreg ## r, r)
@@ -616,6 +643,8 @@ __switch_to(struct task_struct *prev_p,
}
}
+ disable_tsc(prev_p, next_p);
+
return prev_p;
}
diff -puN include/linux/sched.h~x86_64-disable-tsc-with-seccomp include/linux/sched.h
--- devel/include/linux/sched.h~x86_64-disable-tsc-with-seccomp 2006-04-22 01:39:32.000000000 -0700
+++ devel-akpm/include/linux/sched.h 2006-04-22 01:39:32.000000000 -0700
@@ -725,6 +725,8 @@ struct task_struct {
struct sched_info sched_info;
#endif
+ seccomp_t seccomp;
+
struct list_head tasks;
/*
* ptrace_list/ptrace_children forms the list of my children
@@ -824,7 +826,6 @@ struct task_struct {
void *security;
struct audit_context *audit_context;
- seccomp_t seccomp;
/* Thread group tracking */
u32 parent_exec_id;
_
Patches currently in -mm which might be from andrea@xxxxxxxxxxxx are
x86_64-disable-tsc-with-seccomp.patch
-
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