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arm: VFP: Report bounce statistics using procfs

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Report VFP instruction bounce statistics in procfs to aid
in detecting userspace applications that use deprecated VFP
instructions.

Change-Id: Id32387cc6ced399ef6be9c827a9b9c7d52e83e77
Signed-off-by: Stepan Moskovchenko <stepanm@codeaurora.org>
This commit is contained in:
Stepan Moskovchenko
2012-05-29 16:34:41 -07:00
committed by Stephen Boyd
parent 58dff12cbb
commit 8cb58fdfbb
1 changed files with 40 additions and 1 deletions
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41
arch/arm/vfp/vfpmodule.c
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@@ -20,6 +20,7 @@
#include <linux/init.h>
#include <linux/uaccess.h>
#include <linux/user.h>
#include <linux/proc_fs.h>
#include <asm/cp15.h>
#include <asm/cputype.h>
@@ -86,6 +87,11 @@ static void vfp_force_reload(unsigned int cpu, struct thread_info *thread)
#endif
}
/*
* Used for reporting emulation statistics via /proc
*/
static atomic64_t vfp_bounce_count = ATOMIC64_INIT(0);
/*
* Per-thread VFP initialization.
*/
@@ -337,6 +343,7 @@ void VFP_bounce(u32 trigger, u32 fpexc, struct pt_regs *regs)
u32 fpscr, orig_fpscr, fpsid, exceptions;
pr_debug("VFP: bounce: trigger %08x fpexc %08x\n", trigger, fpexc);
atomic64_inc(&vfp_bounce_count);
/*
* At this point, FPEXC can have the following configuration:
@@ -648,6 +655,26 @@ static int vfp_hotplug(struct notifier_block *b, unsigned long action,
return NOTIFY_OK;
}
#ifdef CONFIG_PROC_FS
static int proc_read_status(char *page, char **start, off_t off, int count,
int *eof, void *data)
{
char *p = page;
int len;
p += snprintf(p, PAGE_SIZE, "%llu\n", atomic64_read(&vfp_bounce_count));
len = (p - page) - off;
if (len < 0)
len = 0;
*eof = (len <= count) ? 1 : 0;
*start = page + off;
return len;
}
#endif
/*
* VFP support code initialisation.
*/
@@ -655,7 +682,9 @@ static int __init vfp_init(void)
{
unsigned int vfpsid;
unsigned int cpu_arch = cpu_architecture();
#ifdef CONFIG_PROC_FS
static struct proc_dir_entry *procfs_entry;
#endif
if (cpu_arch >= CPU_ARCH_ARMv6)
on_each_cpu(vfp_enable, NULL, 1);
@@ -724,6 +753,16 @@ static int __init vfp_init(void)
elf_hwcap |= HWCAP_VFPv4;
}
}
#ifdef CONFIG_PROC_FS
procfs_entry = create_proc_entry("cpu/vfp_bounce", S_IRUGO, NULL);
if (procfs_entry)
procfs_entry->read_proc = proc_read_status;
else
pr_err("Failed to create procfs node for VFP bounce reporting\n");
#endif
return 0;
}