From b74e34e6f53816ad57b13ba6fd70a97db1bc1eae Mon Sep 17 00:00:00 2001 From: Khem Raj Date: Thu, 31 Dec 2015 15:15:09 -0800 Subject: [PATCH 21/24] eglibc: Clear cache lines on ppc8xx 2007-06-13 Nathan Sidwell Mark Shinwell * 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 Signed-off-by: Khem Raj --- sysdeps/unix/sysv/linux/powerpc/dl-sysdep.c | 14 +++++++++++++- sysdeps/unix/sysv/linux/powerpc/libc-start.c | 16 +++++++++++++++- 2 files changed, 28 insertions(+), 2 deletions(-) diff --git a/sysdeps/unix/sysv/linux/powerpc/dl-sysdep.c b/sysdeps/unix/sysv/linux/powerpc/dl-sysdep.c index c2504ff..d50f1cb 100644 --- a/sysdeps/unix/sysv/linux/powerpc/dl-sysdep.c +++ b/sysdeps/unix/sysv/linux/powerpc/dl-sysdep.c @@ -24,9 +24,21 @@ int __cache_line_size attribute_hidden; /* 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; diff --git a/sysdeps/unix/sysv/linux/powerpc/libc-start.c b/sysdeps/unix/sysv/linux/powerpc/libc-start.c index 209a16d..5d8572d 100644 --- a/sysdeps/unix/sysv/linux/powerpc/libc-start.c +++ b/sysdeps/unix/sysv/linux/powerpc/libc-start.c @@ -73,11 +73,25 @@ __libc_start_main (int argc, char **argv, /* Initialize the __cache_line_size variable from the aux vector. For the static case, we also need _dl_hwcap, _dl_hwcap2 and _dl_platform, so we - can call __tcb_parse_hwcap_and_convert_at_platform (). */ + can call __tcb_parse_hwcap_and_convert_at_platform (). + + 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; #ifndef SHARED -- 2.6.4