[PATCH v7 00/10] Improve signal performance on PPC64 with KUAP

[Michael Ellerman]

On Fri, 26 Feb 2021 19:12:49 -0600, Christopher M. Riedl wrote:
> As reported by Anton, there is a large penalty to signal handling
> performance on radix systems using KUAP. The signal handling code
> performs many user access operations, each of which needs to switch the
> KUAP permissions bit to open and then close user access. This involves a
> costly 'mtspr' operation [0].
> 
> There is existing work done on x86 and by Christophe Leroy for PPC32 to
> instead open up user access in "blocks" using user_*_access_{begin,end}.
> We can do the same in PPC64 to bring performance back up on KUAP-enabled
> radix and now also hash MMU systems [1].
> 
> [...]

Applied to powerpc/next.

[01/10] powerpc/uaccess: Add unsafe_copy_from_user()
        https://git.kernel.org/powerpc/c/9466c1799fa2acb68e505a264dcdf53779101ac6
[02/10] powerpc/signal: Add unsafe_copy_{vsx, fpr}_from_user()
        https://git.kernel.org/powerpc/c/609355dfc88e2921bfcbd879300d482a9a33378e
[03/10] powerpc/signal64: Remove non-inline calls from setup_sigcontext()
        https://git.kernel.org/powerpc/c/c6c9645e37483444ec5182373455b2f22e4b1535
[04/10] powerpc: Reference parameter in MSR_TM_ACTIVE() macro
        https://git.kernel.org/powerpc/c/1a130b67c682be9842f188f593c2080786de4204
[05/10] powerpc/signal64: Remove TM ifdefery in middle of if/else block
        https://git.kernel.org/powerpc/c/2d19630e20fe5fbd5813f73fd5b1c81ddec61369
[06/10] powerpc/signal64: Replace setup_sigcontext() w/ unsafe_setup_sigcontext()
        https://git.kernel.org/powerpc/c/7bb081c8f043ab166f8c6f26fca744821217dad7
[07/10] powerpc/signal64: Replace restore_sigcontext() w/ unsafe_restore_sigcontext()
        https://git.kernel.org/powerpc/c/193323e1009437c0885240e75ca71f7963e4a006
[08/10] powerpc/signal64: Rewrite handle_rt_signal64() to minimise uaccess switches
        https://git.kernel.org/powerpc/c/96d7a4e06fab9fbc4f67c563af65b073902f3e61
[09/10] powerpc/signal64: Rewrite rt_sigreturn() to minimise uaccess switches
        https://git.kernel.org/powerpc/c/0f92433b8f9f76608528101e7a81cd3bfd00e236
[10/10] powerpc/signal: Use __get_user() to copy sigset_t
        https://git.kernel.org/powerpc/c/d3ccc9781560af051554017c702631560bdc0811

cheers