[2/2] Fast tracepoint for powerpc64le
Commit Message
Hi,
This patch adds an IPA function, jump_pad_area_hint, for giving a hint
where to map jump pad buffer. addr = pagesize is too low for powerpr
executable.
Besides, "MAP_FIXED" flag is removed. See MMAP(2)
If the memory region specified by addr and len overlaps pages
of any existing mapping(s), then the overlapped part of the existing
^^^^^^^^^^^^
mapping(s) will be discarded.
^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Thanks,
Wei-cheng
---
gdb/gdbserver/ChangeLog
2015-02-20 Wei-cheng Wang <cole945@gmail.com>
* tracepoint.c (initialize_tracepoint): Calling jump_pad_area_hint()
to get where to map gdb_jump_pad_buffer. Remove MAP_FIXED.
* tracepoint.h (jump_pad_area_hint): Add declaration.
* linux-amd64-ipa.c (jump_pad_area_hint): New function.
* linux-i386-ipa.c (jump_pad_area_hint): New function.
* linux-ppc-ipa.c (jump_pad_area_hint): New function.
---
gdb/gdbserver/linux-amd64-ipa.c | 11 +++++++++++
gdb/gdbserver/linux-i386-ipa.c | 11 +++++++++++
gdb/gdbserver/linux-ppc-ipa.c | 12 ++++++++++++
gdb/gdbserver/tracepoint.c | 7 +++----
gdb/gdbserver/tracepoint.h | 1 +
5 files changed, 38 insertions(+), 4 deletions(-)
Comments
On 02/20/2015 06:05 PM, Wei-cheng Wang wrote:
> gdb/gdbserver/ChangeLog
>
> 2015-02-20 Wei-cheng Wang <cole945@gmail.com>
>
> * tracepoint.c (initialize_tracepoint): Calling jump_pad_area_hint()
> to get where to map gdb_jump_pad_buffer. Remove MAP_FIXED.
Write:
* tracepoint.c (initialize_tracepoint): Call jump_pad_area_hint
to get where to map gdb_jump_pad_buffer. Remove MAP_FIXED.
> * tracepoint.h (jump_pad_area_hint): Add declaration.
> * linux-amd64-ipa.c (jump_pad_area_hint): New function.
> * linux-i386-ipa.c (jump_pad_area_hint): New function.
> * linux-ppc-ipa.c (jump_pad_area_hint): New function.
I'll leave the PPC-specifics to Ulrich, but otherwise this looks
fine to me, with a nit.
>
> +/* Return the address for where to allocate buffer for jump pad.
> + The buffer should be close enough for tracepoints. */
> +
> +uintptr_t
> +jump_pad_area_hint (void)
> +/* Return the address for where to allocate buffer for jump pad.
> + The buffer should be close enough for tracepoints. */
> +
> +uintptr_t
> +jump_pad_area_hint (void)
> +/* Return the address for where to allocate buffer for jump pad.
> + The buffer should be close enough for tracepoints. */
> +
> +uintptr_t
> +jump_pad_area_hint (void)
Could you move this duplicated comments to the declaration
instead? Then in the implementations' comment you can
just write:
/* See tracepoint.h. */
Thanks,
Pedro Alves
@@ -77,6 +77,17 @@ gdb_agent_get_raw_reg (const unsigned char *raw_regs, int regnum)
return *(ULONGEST *) (raw_regs + x86_64_ft_collect_regmap[regnum]);
}
+/* Return the address for where to allocate buffer for jump pad.
+ The buffer should be close enough for tracepoints. */
+
+uintptr_t
+jump_pad_area_hint (void)
+{
+ /* Allocate scratch buffer aligned on a page boundary, at a low
+ address (close to the main executable's code). */
+ return sysconf (_SC_PAGE_SIZE);
+}
+
#ifdef HAVE_UST
#include <ust/processor.h>
@@ -114,6 +114,17 @@ gdb_agent_get_raw_reg (unsigned char *raw_regs, int regnum)
return *(int *) (raw_regs + i386_ft_collect_regmap[regnum]);
}
+/* Return the address for where to allocate buffer for jump pad.
+ The buffer should be close enough for tracepoints. */
+
+uintptr_t
+jump_pad_area_hint (void)
+{
+ /* Allocate scratch buffer aligned on a page boundary, at a low
+ address (close to the main executable's code). */
+ return sysconf (_SC_PAGE_SIZE);
+}
+
#ifdef HAVE_UST
#include <ust/processor.h>
@@ -105,6 +105,18 @@ gdb_agent_get_raw_reg (const unsigned char *raw_regs, int regnum)
+ ppc_ft_collect_regmap[regnum] * REGSZ);
}
+/* Return the address for where to allocate buffer for jump pad.
+ The buffer should be close enough for tracepoints. */
+
+uintptr_t
+jump_pad_area_hint (void)
+{
+ /* Main executables are normally mapped at 256MB. Unconditional branch
+ can jump +/- 25-bit far (+/- 32MB), so allocate the buffer at 240MB
+ should be close enough in most cases. */
+ return 0xf000000;
+}
+
/* Initialize ipa_tdesc and others. */
void
@@ -7388,13 +7388,12 @@ initialize_tracepoint (void)
#define SCRATCH_BUFFER_NPAGES 20
- /* Allocate scratch buffer aligned on a page boundary, at a low
- address (close to the main executable's code). */
- for (addr = pagesize; addr != 0; addr += pagesize)
+ addr = jump_pad_area_hint ();
+ for (; addr != 0; addr += pagesize)
{
gdb_jump_pad_buffer = mmap ((void *) addr, pagesize * SCRATCH_BUFFER_NPAGES,
PROT_READ | PROT_WRITE | PROT_EXEC,
- MAP_PRIVATE | MAP_ANONYMOUS | MAP_FIXED,
+ MAP_PRIVATE | MAP_ANONYMOUS,
-1, 0);
if (gdb_jump_pad_buffer != MAP_FAILED)
break;
@@ -88,6 +88,7 @@ void supply_static_tracepoint_registers (struct regcache *regcache,
CORE_ADDR pc);
void set_trampoline_buffer_space (CORE_ADDR begin, CORE_ADDR end,
char *errmsg);
+uintptr_t jump_pad_area_hint (void);
extern const struct target_desc *ipa_tdesc;