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kernel modules: hack up quick floating point example

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Ciro Santilli 六四事件 法轮功
2019-06-02 00:00:01 +00:00
parent 7f917af66b
commit 819ef42ea4
5 changed files with 121 additions and 11 deletions
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5
kernel_modules/Makefile
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@@ -13,6 +13,11 @@ ccflags-y := \
-Wno-declaration-after-statement \
$(CCFLAGS)
ifeq ($(ARCH),x86)
# https://github.com/cirosantilli/linux-kernel-module-cheat#floating-point-in-kernel-modules
CFLAGS_REMOVE_float.o += -mno-sse -mno-sse2
endif
.PHONY: all
all:

31
kernel_modules/float.c Normal file
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@@ -0,0 +1,31 @@
/* https://github.com/cirosantilli/linux-kernel-module-cheat#floating-point-in-kernel-modules */
#include <linux/kernel.h>
#include <linux/module.h>
#include <asm/fpu/api.h> /* kernel_fpu_begin, kernel_fpu_end */
/* float params are not supported, so we just go with int. */
static int myfloat = 1;
static int enable_fpu = 1;
module_param(myfloat, int, S_IRUSR | S_IWUSR);
module_param(enable_fpu, int, S_IRUSR | S_IWUSR);
static int myinit(void)
{
if (enable_fpu) {
kernel_fpu_begin();
}
if ((float)myfloat + 1.5f == 2.5f) {
pr_info("magic value\n");
}
if (enable_fpu) {
kernel_fpu_end();
}
return 0;
}
static void myexit(void) {}
module_init(myinit)
module_exit(myexit)
MODULE_LICENSE("GPL");