From: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx> local_flush_tlb() does a CR3 write. But, that kind of TLB flush is not guaranteed to invalidate global pages. The entire kernel is mapped with global pages. Also, now that we have PCIDs, local_flush_tlb() will only flush the *current* PCID. It would not flush the entries for all PCIDs. At the moment, this is a moot point because all kernel pages are _PAGE_GLOBAL which do not really *have* a particular PCID. Use the stronger __flush_tlb_all() which does flush global pages. This was found because of a warning I added to __native_flush_tlb() to look for calls to it when PCIDs are enabled. This patch does not fix any bug known to be hit in practice. Signed-off-by: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx> Cc: x86@xxxxxxxxxx Cc: Andy Lutomirski <luto@xxxxxxxxxx> --- b/arch/x86/kernel/alternative.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff -puN arch/x86/kernel/alternative.c~x86-mm-text-poke-misses-global-pages arch/x86/kernel/alternative.c --- a/arch/x86/kernel/alternative.c~x86-mm-text-poke-misses-global-pages 2017-10-31 10:28:44.306557256 -0700 +++ b/arch/x86/kernel/alternative.c 2017-10-31 10:28:44.309557393 -0700 @@ -722,7 +722,8 @@ void *text_poke(void *addr, const void * clear_fixmap(FIX_TEXT_POKE0); if (pages[1]) clear_fixmap(FIX_TEXT_POKE1); - local_flush_tlb(); + /* Make sure to flush Global pages: */ + __flush_tlb_all(); sync_core(); /* Could also do a CLFLUSH here to speed up CPU recovery; but that causes hangs on some VIA CPUs. */ _ -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>
