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2007-06-13 Nathan Sidwell <nathan@codesourcery.com>
Mark Shinwell <shinwell@codesourcery.com>
* sysdeps/unix/sysv/linux/powerpc/libc-start.c
(__libc_start_main): Detect 8xx parts and clear
__cache_line_size if detected.
* sysdeps/unix/sysv/linux/powerpc/dl-sysdep.c
(DL_PLATFORM_AUXV): Likewise.
Upstream-Status: Pending
Index: git/sysdeps/unix/sysv/linux/powerpc/dl-sysdep.c
===================================================================
--- git.orig/sysdeps/unix/sysv/linux/powerpc/dl-sysdep.c 2014-08-27 18:49:23.996070587 +0000
+++ git/sysdeps/unix/sysv/linux/powerpc/dl-sysdep.c 2014-08-27 18:49:27.332070587 +0000
@@ -24,9 +24,21 @@
/* Scan the Aux Vector for the "Data Cache Block Size" entry. If found
verify that the static extern __cache_line_size is defined by checking
for not NULL. If it is defined then assign the cache block size
- value to __cache_line_size. */
+ value to __cache_line_size. This is used by memset to
+ optimize setting to zero. We have to detect 8xx processors, which
+ have buggy dcbz implementations that cannot report page faults
+ correctly. That requires reading SPR, which is a privileged
+ operation. Fortunately 2.2.18 and later emulates PowerPC mfspr
+ reads from the PVR register. */
#define DL_PLATFORM_AUXV \
case AT_DCACHEBSIZE: \
+ if (__LINUX_KERNEL_VERSION >= 0x020218) \
+ { \
+ unsigned pvr = 0; \
+ asm ("mfspr %0, 287" : "=r" (pvr)); \
+ if ((pvr & 0xffff0000) == 0x00500000) \
+ break; \
+ } \
__cache_line_size = av->a_un.a_val; \
break;
Index: git/sysdeps/unix/sysv/linux/powerpc/libc-start.c
===================================================================
--- git.orig/sysdeps/unix/sysv/linux/powerpc/libc-start.c 2014-08-27 18:49:23.996070587 +0000
+++ git/sysdeps/unix/sysv/linux/powerpc/libc-start.c 2014-08-27 18:49:27.332070587 +0000
@@ -68,11 +68,24 @@
rtld_fini = NULL;
}
- /* Initialize the __cache_line_size variable from the aux vector. */
+ /* Initialize the __cache_line_size variable from the aux vector.
+ This is used by memset to optimize setting to zero. We have to
+ detect 8xx processors, which have buggy dcbz implementations that
+ cannot report page faults correctly. That requires reading SPR,
+ which is a privileged operation. Fortunately 2.2.18 and later
+ emulates PowerPC mfspr reads from the PVR register. */
for (ElfW (auxv_t) * av = auxvec; av->a_type != AT_NULL; ++av)
switch (av->a_type)
{
case AT_DCACHEBSIZE:
+ if (__LINUX_KERNEL_VERSION >= 0x020218)
+ {
+ unsigned pvr = 0;
+
+ asm ("mfspr %0, 287" : "=r" (pvr) :);
+ if ((pvr & 0xffff0000) == 0x00500000)
+ break;
+ }
__cache_line_size = av->a_un.a_val;
break;
}
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