The branch stable/13 has been updated by dchagin:

URL: 
https://cgit.FreeBSD.org/src/commit/?id=b69b287a0969b9dd27a3184b2141e9a580a64535

commit b69b287a0969b9dd27a3184b2141e9a580a64535
Author:     Dmitry Chagin <dcha...@freebsd.org>
AuthorDate: 2023-02-02 17:21:37 +0000
Commit:     Dmitry Chagin <dcha...@freebsd.org>
CommitDate: 2023-02-09 07:55:24 +0000

    linux(4): Microoptimize rt_sendsig() on amd64.
    
    Drop proc lock earlier, before copying user stuff.
    
    Pointed out by:         kib
    Reviewed by:            kib
    Differential Revision:  https://reviews.freebsd.org/D38326
    MFC after:              1 week
    
    (cherry picked from commit 6ad07a4b2bdf0856545ff8495a7b3396695814fa)
---
 sys/amd64/linux/linux_sysvec.c | 34 +++++++++++++++++-----------------
 1 file changed, 17 insertions(+), 17 deletions(-)

diff --git a/sys/amd64/linux/linux_sysvec.c b/sys/amd64/linux/linux_sysvec.c
index 9e36f8739556..d7e33ccb8b70 100644
--- a/sys/amd64/linux/linux_sysvec.c
+++ b/sys/amd64/linux/linux_sysvec.c
@@ -464,16 +464,29 @@ linux_rt_sendsig(sig_t catcher, ksiginfo_t *ksi, sigset_t 
*mask)
        LINUX_CTR4(rt_sendsig, "%p, %d, %p, %u",
            catcher, sig, mask, code);
 
-       /* Save user context. */
        bzero(&sf, sizeof(sf));
-       bsd_to_linux_sigset(mask, &sf.sf_uc.uc_sigmask);
-       sf.sf_uc.uc_mcontext.sc_mask = sf.sf_uc.uc_sigmask;
-
        sf.sf_uc.uc_stack.ss_sp = PTROUT(td->td_sigstk.ss_sp);
        sf.sf_uc.uc_stack.ss_size = td->td_sigstk.ss_size;
        sf.sf_uc.uc_stack.ss_flags = (td->td_pflags & TDP_ALTSTACK)
            ? ((oonstack) ? LINUX_SS_ONSTACK : 0) : LINUX_SS_DISABLE;
 
+       /* Allocate space for the signal handler context. */
+       if ((td->td_pflags & TDP_ALTSTACK) != 0 && !oonstack &&
+           SIGISMEMBER(psp->ps_sigonstack, sig)) {
+               sp = (caddr_t)td->td_sigstk.ss_sp + td->td_sigstk.ss_size;
+       } else
+               sp = (caddr_t)regs->tf_rsp - 128;
+
+       mtx_unlock(&psp->ps_mtx);
+       PROC_UNLOCK(p);
+
+       /* Make room, keeping the stack aligned. */
+       sp -= sizeof(struct l_rt_sigframe);
+       sfp = (struct l_rt_sigframe *)((unsigned long)sp & ~0xFul);
+
+       /* Save user context. */
+       bsd_to_linux_sigset(mask, &sf.sf_uc.uc_sigmask);
+       sf.sf_uc.uc_mcontext.sc_mask   = sf.sf_uc.uc_sigmask;
        sf.sf_uc.uc_mcontext.sc_rdi    = regs->tf_rdi;
        sf.sf_uc.uc_mcontext.sc_rsi    = regs->tf_rsi;
        sf.sf_uc.uc_mcontext.sc_rdx    = regs->tf_rdx;
@@ -497,19 +510,6 @@ linux_rt_sendsig(sig_t catcher, ksiginfo_t *ksi, sigset_t 
*mask)
        sf.sf_uc.uc_mcontext.sc_trapno = bsd_to_linux_trapcode(code);
        sf.sf_uc.uc_mcontext.sc_cr2    = (register_t)ksi->ksi_addr;
 
-       /* Allocate space for the signal handler context. */
-       if ((td->td_pflags & TDP_ALTSTACK) != 0 && !oonstack &&
-           SIGISMEMBER(psp->ps_sigonstack, sig)) {
-               sp = (caddr_t)td->td_sigstk.ss_sp + td->td_sigstk.ss_size;
-       } else
-               sp = (caddr_t)regs->tf_rsp - 128;
-       sp -= sizeof(struct l_rt_sigframe);
-       /* Align to 16 bytes. */
-       sfp = (struct l_rt_sigframe *)((unsigned long)sp & ~0xFul);
-
-       mtx_unlock(&psp->ps_mtx);
-       PROC_UNLOCK(p);
-
        get_fpcontext(td, &mc, NULL, NULL);
        KASSERT(mc.mc_fpformat != _MC_FPFMT_NODEV, ("fpu not present"));
        svfp = (struct savefpu *)mc.mc_fpstate;

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