| # commit 0b2c2ace3601d5d59cf89130b16840e7f132f7a6 |
| # Author: Alan Modra <amodra@gmail.com> |
| # Date: Sat Aug 17 18:36:45 2013 +0930 |
| # |
| # PowerPC makecontext |
| # http://sourceware.org/ml/libc-alpha/2013-08/msg00092.html |
| # |
| # Use conditional form of branch and link to avoid destroying the cpu |
| # link stack used to predict blr return addresses. |
| # |
| # * sysdeps/unix/sysv/linux/powerpc/powerpc32/makecontext.S: Use |
| # conditional form of branch and link when obtaining pc. |
| # * sysdeps/unix/sysv/linux/powerpc/powerpc64/makecontext.S: Likewise. |
| # |
| diff -urN glibc-2.17-c758a686/sysdeps/unix/sysv/linux/powerpc/powerpc32/makecontext.S glibc-2.17-c758a686/sysdeps/unix/sysv/linux/powerpc/powerpc32/makecontext.S |
| |
| |
| @@ -47,7 +47,9 @@ |
| #ifdef PIC |
| mflr r0 |
| cfi_register(lr,r0) |
| - bl 1f |
| + /* Use this conditional form of branch and link to avoid destroying |
| + the cpu link stack used to predict blr return addresses. */ |
| + bcl 20,31,1f |
| 1: mflr r6 |
| addi r6,r6,L(exitcode)-1b |
| mtlr r0 |
| @@ -136,7 +138,9 @@ |
| #ifdef PIC |
| mflr r0 |
| cfi_register(lr,r0) |
| - bl 1f |
| + /* Use this conditional form of branch and link to avoid destroying |
| + the cpu link stack used to predict blr return addresses. */ |
| + bcl 20,31,1f |
| 1: mflr r6 |
| addi r6,r6,L(novec_exitcode)-1b |
| mtlr r0 |
| diff -urN glibc-2.17-c758a686/sysdeps/unix/sysv/linux/powerpc/powerpc64/makecontext.S glibc-2.17-c758a686/sysdeps/unix/sysv/linux/powerpc/powerpc64/makecontext.S |
| |
| |
| @@ -124,8 +124,10 @@ |
| |
| /* If the target function returns we need to do some cleanup. We use a |
| code trick to get the address of our cleanup function into the link |
| - register. Do not add any code between here and L(exitcode). */ |
| - bl L(gotexitcodeaddr); |
| + register. Do not add any code between here and L(exitcode). |
| + Use this conditional form of branch and link to avoid destroying |
| + the cpu link stack used to predict blr return addresses. */ |
| + bcl 20,31,L(gotexitcodeaddr); |
| |
| /* This is the helper code which gets called if a function which |
| is registered with 'makecontext' returns. In this case we |