Re: [PATCH V3 2/3] perf/powerpc :add support for sampling intr machine state

On Tuesday 03 November 2015 02:46 PM, Michael Ellerman wrote:

On Tue, 2015-11-03 at 11:40 +0530, Anju T wrote:

quoted

The perf infrastructure uses a bit mask to find out
valid registers to display. Define a register mask
for supported registers defined in asm/perf_regs.h.
The bit positions also correspond to register IDs
which is used by perf infrastructure to fetch the register
values.CONFIG_HAVE_PERF_REGS enables
sampling of the interrupted machine state.

diff --git a/arch/powerpc/perf/perf_regs.c b/arch/powerpc/perf/perf_regs.c
new file mode 100644
index 0000000..0520492
--- /dev/null
+++ b/arch/powerpc/perf/perf_regs.c

@@ -0,0 +1,92 @@
+#include <linux/errno.h>
+#include <linux/kernel.h>
+#include <linux/sched.h>
+#include <linux/perf_event.h>
+#include <linux/bug.h>
+#include <linux/stddef.h>
+#include <asm/ptrace.h>
+#include <asm/perf_regs.h>
+
+#define PT_REGS_OFFSET(id, r) [id] = offsetof(struct pt_regs, r)
+
+#define REG_RESERVED (~((1ULL << PERF_REG_POWERPC_MAX) - 1))
+
+static unsigned int pt_regs_offset[PERF_REG_POWERPC_MAX] = {
+	PT_REGS_OFFSET(PERF_REG_POWERPC_GPR0, gpr[0]),
+	PT_REGS_OFFSET(PERF_REG_POWERPC_GPR1, gpr[1]),
+	PT_REGS_OFFSET(PERF_REG_POWERPC_GPR2, gpr[2]),

<snip>

I realise you're following the example of other architectures, but we have
almost this exact same structure in ptrace.c, see regoffset_table.

That won't work because we want to add more regs to the perf version but
not the ptrace version.

Maddy

It would be really nice if we could share them between ptrace and perf.

cheers

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