On Tue, May 29, 2012 at 03:09:43PM +0100, Al Viro wrote: > On Tue, May 29, 2012 at 12:55:10AM -0400, Matt Turner wrote: > > > I recently looked at this gentoo bug -- > > https://bugs.gentoo.org/show_bug.cgi?id=405829 and then came across > > this email and the two patches. They seem possibly related. > > > > It looks like Al said he thought he had a better way of fixing the > > problem, but then I'm not sure if his patches surfaced or not. > > > > Also possibly related, Tobias and Michael have seen some RCU stalls > > with recent kernels. Looks like getxpid needs an update? > > Umm... Let me see if I can find it... Here: [snip] BTW, there's another completely untested patch bouncing around in the local tree - takes kernel_execve() out of entry.S diff --git a/arch/alpha/kernel/alpha_ksyms.c b/arch/alpha/kernel/alpha_ksyms.c index d96e742..b77b813 100644 --- a/arch/alpha/kernel/alpha_ksyms.c +++ b/arch/alpha/kernel/alpha_ksyms.c @@ -52,7 +52,6 @@ EXPORT_SYMBOL(alpha_write_fp_reg_s); /* entry.S */ EXPORT_SYMBOL(kernel_thread); -EXPORT_SYMBOL(kernel_execve); /* Networking helper routines. */ EXPORT_SYMBOL(csum_tcpudp_magic); diff --git a/arch/alpha/kernel/entry.S b/arch/alpha/kernel/entry.S index 4074645..a8c9db8 100644 --- a/arch/alpha/kernel/entry.S +++ b/arch/alpha/kernel/entry.S @@ -663,58 +663,6 @@ kernel_thread: br ret_to_kernel .end kernel_thread -/* - * kernel_execve(path, argv, envp) - */ - .align 4 - .globl kernel_execve - .ent kernel_execve -kernel_execve: - /* We can be called from a module. */ - ldgp $gp, 0($27) - lda $sp, -(32+SIZEOF_PT_REGS+8)($sp) - .frame $sp, 32+SIZEOF_PT_REGS+8, $26, 0 - stq $26, 0($sp) - stq $16, 8($sp) - stq $17, 16($sp) - stq $18, 24($sp) - .prologue 1 - - lda $16, 32($sp) - lda $17, 0 - lda $18, SIZEOF_PT_REGS - bsr $26, memset !samegp - - /* Avoid the HAE being gratuitously wrong, which would cause us - to do the whole turn off interrupts thing and restore it. */ - ldq $2, alpha_mv+HAE_CACHE - stq $2, 152+32($sp) - - ldq $16, 8($sp) - ldq $17, 16($sp) - ldq $18, 24($sp) - lda $19, 32($sp) - bsr $26, do_execve !samegp - - ldq $26, 0($sp) - bne $0, 1f /* error! */ - - /* Move the temporary pt_regs struct from its current location - to the top of the kernel stack frame. See copy_thread for - details for a normal process. */ - lda $16, 0x4000 - SIZEOF_PT_REGS($8) - lda $17, 32($sp) - lda $18, SIZEOF_PT_REGS - bsr $26, memmove !samegp - - /* Take that over as our new stack frame and visit userland! */ - lda $sp, 0x4000 - SIZEOF_PT_REGS($8) - br $31, ret_from_sys_call - -1: lda $sp, 32+SIZEOF_PT_REGS+8($sp) - ret -.end kernel_execve - /* * Special system calls. Most of these are special in that they either diff --git a/arch/alpha/kernel/process.c b/arch/alpha/kernel/process.c index 153d3fc..d6fde98 100644 --- a/arch/alpha/kernel/process.c +++ b/arch/alpha/kernel/process.c @@ -455,3 +455,22 @@ get_wchan(struct task_struct *p) } return pc; } + +int kernel_execve(const char *path, const char *const argv[], const char *const envp[]) +{ + /* Avoid the HAE being gratuitously wrong, which would cause us + to do the whole turn off interrupts thing and restore it. */ + struct pt_regs regs = {.hae = alpha_mv.hae_cache}; + int err = do_execve(path, argv, envp, ®s); + if (!err) { + struct pt_regs *p = current_pt_regs(); + /* copy regs to normal position and off to userland we go... */ + *p = regs; + __asm__ __volatile__ ( + "mov %0, $sp;" + "br $31, ret_from_sys_call" + : : "r"(p)); + } + return err; +} +EXPORT_SYMBOL(kernel_execve); -- To unsubscribe from this list: send the line "unsubscribe linux-alpha" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
