Revert "MFC r321899"

This reverts commit 1027b09f970c81aab8f721168a4500261978c198.

4 files changed, 1 insertions, 52 deletions

diff --git a/sys/amd64/amd64/elf_machdep.c b/sys/amd64/amd64/elf_machdep.c
index 4e9476a..ca07adc 100644
--- a/sys/amd64/amd64/elf_machdep.c
+++ b/sys/amd64/amd64/elf_machdep.c
@@ -84,25 +84,6 @@ struct sysentvec elf64_freebsd_sysvec = {
 };
 INIT_SYSENTVEC(elf64_sysvec, &elf64_freebsd_sysvec);
 
-void
-amd64_lower_shared_page(struct sysentvec *sv)
-{
-	if (hw_lower_amd64_sharedpage != 0) {
-		sv->sv_maxuser -= PAGE_SIZE;
-		sv->sv_shared_page_base -= PAGE_SIZE;
-		sv->sv_usrstack -= PAGE_SIZE;
-		sv->sv_psstrings -= PAGE_SIZE;
-	}
-}
-
-/*
- * Do this fixup before INIT_SYSENTVEC (SI_ORDER_ANY) because the latter
- * uses the value of sv_shared_page_base.
- */
-SYSINIT(elf64_sysvec_fixup, SI_SUB_EXEC, SI_ORDER_FIRST,
-	(sysinit_cfunc_t) amd64_lower_shared_page,
-	&elf64_freebsd_sysvec);
-
 static Elf64_Brandinfo freebsd_brand_info = {
 	.brand		= ELFOSABI_FREEBSD,
 	.machine	= EM_X86_64,
diff --git a/sys/amd64/amd64/initcpu.c b/sys/amd64/amd64/initcpu.c
index ff3b6be..63c0f20 100644
--- a/sys/amd64/amd64/initcpu.c
+++ b/sys/amd64/amd64/initcpu.c
@@ -48,11 +48,6 @@ __FBSDID("$FreeBSD$");
 static int	hw_instruction_sse;
 SYSCTL_INT(_hw, OID_AUTO, instruction_sse, CTLFLAG_RD,
     &hw_instruction_sse, 0, "SIMD/MMX2 instructions available in CPU");
-static int	lower_sharedpage_init;
-int		hw_lower_amd64_sharedpage;
-SYSCTL_INT(_hw, OID_AUTO, lower_amd64_sharedpage, CTLFLAG_RDTUN,
-    &hw_lower_amd64_sharedpage, 0,
-   "Lower sharedpage to work around Ryzen issue with executing code near the top of user memory");
 /*
  * -1: automatic (default)
  *  0: keep enable CLFLUSH
@@ -127,28 +122,6 @@ init_amd(void)
 			wrmsr(0xc0011020, msr);
 		}
 	}
-
-	/*
-	 * Work around a problem on Ryzen that is triggered by executing
-	 * code near the top of user memory, in our case the signal
-	 * trampoline code in the shared page on amd64.
-	 *
-	 * This function is executed once for the BSP before tunables take
-	 * effect so the value determined here can be overridden by the
-	 * tunable.  This function is then executed again for each AP and
-	 * also on resume.  Set a flag the first time so that value set by
-	 * the tunable is not overwritten.
-	 *
-	 * The stepping and/or microcode versions should be checked after
-	 * this issue is fixed by AMD so that we don't use this mode if not
-	 * needed.
-	 */
-	if (lower_sharedpage_init == 0) {
-		lower_sharedpage_init = 1;
-		if (CPUID_TO_FAMILY(cpu_id) == 0x17) {
-			hw_lower_amd64_sharedpage = 1;
-		}
-	}
 }
 
 /*
diff --git a/sys/amd64/include/md_var.h b/sys/amd64/include/md_var.h
index 7a84631..706ffc6 100644
--- a/sys/amd64/include/md_var.h
+++ b/sys/amd64/include/md_var.h
@@ -34,15 +34,12 @@
 
 #include <x86/x86_var.h>
 
-extern uint64_t	*vm_page_dump;
-extern int	hw_lower_amd64_sharedpage;
+extern  uint64_t *vm_page_dump;
 
 struct	savefpu;
-struct	sysentvec;
 
 void	amd64_conf_fast_syscall(void);
 void	amd64_db_resume_dbreg(void);
-void	amd64_lower_shared_page(struct sysentvec *);
 void	amd64_syscall(struct thread *td, int traced);
 void	doreti_iret(void) __asm(__STRING(doreti_iret));
 void	doreti_iret_fault(void) __asm(__STRING(doreti_iret_fault));
diff --git a/sys/amd64/linux/linux_sysvec.c b/sys/amd64/linux/linux_sysvec.c
index 942819b..f77c2c9 100644
--- a/sys/amd64/linux/linux_sysvec.c
+++ b/sys/amd64/linux/linux_sysvec.c
@@ -833,8 +833,6 @@ static void
 linux_vdso_install(void *param)
 {
 
-	amd64_lower_shared_page(&elf_linux_sysvec);
-
 	linux_szsigcode = (&_binary_linux_locore_o_end - 
 	    &_binary_linux_locore_o_start);