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authorArd Biesheuvel <ardb@kernel.org>2023-03-18 17:24:27 +0100
committerArd Biesheuvel <ardb@kernel.org>2023-05-16 20:24:08 +0200
commit8769177658d3559c4323200a719dd456d2f2675a (patch)
tree0720bd3cf595858aed661c4f9ddb51e5a3131954 /arch/arm/vfp
parentf1fcbaa18b28dec10281551dfe6ed3a3ed80e3d6 (diff)
ARM: vfp: Record VFP bounces as perf emulation faults
VFP 'bouncing' occurs when the VFP unit cannot complete the execution of a VFP instruction, either because it is not implemented at all, or because the values of the arguments are out of range for the hardware implementation, and the software needs to step in to complete the operation. To give some insight in how much certain programs rely on this bouncing, record the emulation of a VFP instruction in perf's emulation-faults counter. This can be used like so perf stat -e emulation-faults ./testfloat -all2 and the output will be something like Performance counter stats for './testfloat -all2': 259,277 emulation-faults:u 6.846432176 seconds time elapsed Reviewed-by: Linus Walleij <linus.walleij@linaro.org> Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Diffstat (limited to 'arch/arm/vfp')
-rw-r--r--arch/arm/vfp/vfpmodule.c2
1 files changed, 2 insertions, 0 deletions
diff --git a/arch/arm/vfp/vfpmodule.c b/arch/arm/vfp/vfpmodule.c
index 349dcb944a93..08d5dfcf7079 100644
--- a/arch/arm/vfp/vfpmodule.c
+++ b/arch/arm/vfp/vfpmodule.c
@@ -18,6 +18,7 @@
#include <linux/uaccess.h>
#include <linux/user.h>
#include <linux/export.h>
+#include <linux/perf_event.h>
#include <asm/cp15.h>
#include <asm/cputype.h>
@@ -313,6 +314,7 @@ static u32 vfp_emulate_instruction(u32 inst, u32 fpscr, struct pt_regs *regs)
* emulate it.
*/
}
+ perf_sw_event(PERF_COUNT_SW_EMULATION_FAULTS, 1, regs, regs->ARM_pc);
return exceptions & ~VFP_NAN_FLAG;
}