Commit 235a6f06 authored by Karol Swietlicki's avatar Karol Swietlicki Committed by Linus Torvalds
Browse files

uml: improve detection of host cmov



This patch introduces a new way of checking for the cmov instruction.  I use
signal handling instead of reading /proc/cpuinfo.

[ jdike - Fiddled the asm to make it obvious that it didn't mess with
any in-use registers and made test_for_host_cmov void ]

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: default avatarKarol Swietlicki <magotari@gmail.com>
Signed-off-by: default avatarJeff Dike <jdike@linux.intel.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 0ba9d3f9
...@@ -18,6 +18,7 @@ DEFINE_STR(UM_KERN_WARNING, KERN_WARNING); ...@@ -18,6 +18,7 @@ DEFINE_STR(UM_KERN_WARNING, KERN_WARNING);
DEFINE_STR(UM_KERN_NOTICE, KERN_NOTICE); DEFINE_STR(UM_KERN_NOTICE, KERN_NOTICE);
DEFINE_STR(UM_KERN_INFO, KERN_INFO); DEFINE_STR(UM_KERN_INFO, KERN_INFO);
DEFINE_STR(UM_KERN_DEBUG, KERN_DEBUG); DEFINE_STR(UM_KERN_DEBUG, KERN_DEBUG);
DEFINE_STR(UM_KERN_CONT, KERN_CONT);
DEFINE(UM_ELF_CLASS, ELF_CLASS); DEFINE(UM_ELF_CLASS, ELF_CLASS);
DEFINE(UM_ELFCLASS32, ELFCLASS32); DEFINE(UM_ELFCLASS32, ELFCLASS32);
......
...@@ -10,11 +10,41 @@ ...@@ -10,11 +10,41 @@
#include "os.h" #include "os.h"
#include "task.h" #include "task.h"
#include "user.h" #include "user.h"
#include "sysdep/archsetjmp.h"
#define MAXTOKEN 64 #define MAXTOKEN 64
/* Set during early boot */ /* Set during early boot */
int host_has_cmov = 1; int host_has_cmov = 1;
static jmp_buf cmov_test_return;
static void cmov_sigill_test_handler(int sig)
{
host_has_cmov = 0;
longjmp(cmov_test_return, 1);
}
static void test_for_host_cmov(void)
{
struct sigaction old, new;
printk(UM_KERN_INFO "Checking for host processor cmov support...");
new.sa_handler = cmov_sigill_test_handler;
/* Make sure that SIGILL is enabled after the handler longjmps back */
new.sa_flags = SA_NODEFER;
sigemptyset(&new.sa_mask);
sigaction(SIGILL, &new, &old);
if (setjmp(cmov_test_return) == 0) {
unsigned long foo = 0;
__asm__ __volatile__("cmovz %0, %1" : "=r" (foo) : "0" (foo));
printk(UM_KERN_CONT "Yes\n");
} else
printk(UM_KERN_CONT "No\n");
sigaction(SIGILL, &old, &new);
}
static char token(int fd, char *buf, int len, char stop) static char token(int fd, char *buf, int len, char stop)
{ {
...@@ -153,15 +183,7 @@ void arch_init_thread(void) ...@@ -153,15 +183,7 @@ void arch_init_thread(void)
void arch_check_bugs(void) void arch_check_bugs(void)
{ {
int have_it; test_for_host_cmov();
if (os_access("/proc/cpuinfo", OS_ACC_R_OK) < 0) {
printk(UM_KERN_ERR "/proc/cpuinfo not available - skipping CPU "
"capability checks\n");
return;
}
if (check_cpu_flag("cmov", &have_it))
host_has_cmov = have_it;
} }
int arch_handle_signal(int sig, struct uml_pt_regs *regs) int arch_handle_signal(int sig, struct uml_pt_regs *regs)
......
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