From 1feb8d2d7396748fb3bd6795d09bbfbdd4c03dff Mon Sep 17 00:00:00 2001 From: Paolo 'Blaisorblade' Giarrusso Date: Thu, 14 Jul 2005 00:33:36 -0700 Subject: [PATCH] [PATCH] uml: workaround host bug in "TT mode vs. NPTL link fix" A big bug has been diagnosed on hosts running the SKAS patch and built with CONFIG_REGPARM, due to some missing prevent_tail_call(). On these hosts, this workaround is needed to avoid triggering that bug, because "to" is kept by GCC only in EBX, which is corrupted at the return of mmap2(). Since to trigger this bug int 0x80 must be used when doing the call, it rarely manifests itself, so I'd prefer to get this merged to workaround that host bug, since it should cause no functional change. Still, you might prefer to drop it, I'll leave this to you. Signed-off-by: Paolo 'Blaisorblade' Giarrusso Cc: Jeff Dike Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- arch/um/sys-i386/unmap.c | 2 +- arch/um/sys-x86_64/unmap.c | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-) diff --git a/arch/um/sys-i386/unmap.c b/arch/um/sys-i386/unmap.c index 136875263d27..1b0ad0e4adcd 100644 --- a/arch/um/sys-i386/unmap.c +++ b/arch/um/sys-i386/unmap.c @@ -15,7 +15,7 @@ int switcheroo(int fd, int prot, void *from, void *to, int size) if(munmap(to, size) < 0){ return(-1); } - if(mmap2(to, size, prot, MAP_SHARED | MAP_FIXED, fd, 0) != to){ + if(mmap2(to, size, prot, MAP_SHARED | MAP_FIXED, fd, 0) == (void*) -1 ){ return(-1); } if(munmap(from, size) < 0){ diff --git a/arch/um/sys-x86_64/unmap.c b/arch/um/sys-x86_64/unmap.c index bc7094cce47e..f4a4bffd8a18 100644 --- a/arch/um/sys-x86_64/unmap.c +++ b/arch/um/sys-x86_64/unmap.c @@ -15,7 +15,7 @@ int switcheroo(int fd, int prot, void *from, void *to, int size) if(munmap(to, size) < 0){ return(-1); } - if(mmap(to, size, prot, MAP_SHARED | MAP_FIXED, fd, 0) != to){ + if(mmap(to, size, prot, MAP_SHARED | MAP_FIXED, fd, 0) == (void*) -1){ return(-1); } if(munmap(from, size) < 0){ -- 2.20.1