powerpc fixes for 5.11 #7

A fix for a change we made to __kernel_sigtramp_rt64() which confused glibc's
 backtrace logic, and also changed the semantics of that symbol, which was
 arguably an ABI break.
 
 A fix for a stack overwrite in our VSX instruction emulation.
 
 A couple of fixes for the Makefile logic in the new C VDSO.
 
 Thanks to: Masahiro Yamada, Naveen N. Rao, Raoni Fassina Firmino, Ravi Bangoria.
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Merge tag 'powerpc-5.11-7' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux

Pull powerpc fixes from Michael Ellerman:

 - A fix for a change we made to __kernel_sigtramp_rt64() which confused
   glibc's backtrace logic, and also changed the semantics of that
   symbol, which was arguably an ABI break.

 - A fix for a stack overwrite in our VSX instruction emulation.

 - A couple of fixes for the Makefile logic in the new C VDSO.

Thanks to Masahiro Yamada, Naveen N.  Rao, Raoni Fassina Firmino, and
Ravi Bangoria.

* tag 'powerpc-5.11-7' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux:
  powerpc/64/signal: Fix regression in __kernel_sigtramp_rt64() semantics
  powerpc/vdso64: remove meaningless vgettimeofday.o build rule
  powerpc/vdso: fix unnecessary rebuilds of vgettimeofday.o
  powerpc/sstep: Fix array out of bound warning

arch/powerpc/kernel/Makefile

@@ -51,7 +51,7 @@ obj-y				+= ptrace/
 obj-$(CONFIG_PPC64)		+= setup_64.o \
 				   paca.o nvram_64.o note.o syscall_64.o
 obj-$(CONFIG_COMPAT)		+= sys_ppc32.o signal_32.o
-obj-$(CONFIG_VDSO32)		+= vdso32/
+obj-$(CONFIG_VDSO32)		+= vdso32_wrapper.o
 obj-$(CONFIG_PPC_WATCHDOG)	+= watchdog.o
 obj-$(CONFIG_HAVE_HW_BREAKPOINT)	+= hw_breakpoint.o
 obj-$(CONFIG_PPC_DAWR)		+= dawr.o
@@ -60,7 +60,7 @@ obj-$(CONFIG_PPC_BOOK3S_64)	+= cpu_setup_power.o
 obj-$(CONFIG_PPC_BOOK3S_64)	+= mce.o mce_power.o
 obj-$(CONFIG_PPC_BOOK3E_64)	+= exceptions-64e.o idle_book3e.o
 obj-$(CONFIG_PPC_BARRIER_NOSPEC) += security.o
-obj-$(CONFIG_PPC64)		+= vdso64/
+obj-$(CONFIG_PPC64)		+= vdso64_wrapper.o
 obj-$(CONFIG_ALTIVEC)		+= vecemu.o
 obj-$(CONFIG_PPC_BOOK3S_IDLE)	+= idle_book3s.o
 procfs-y			:= proc_powerpc.o

arch/powerpc/kernel/vdso32/Makefile

@@ -30,7 +30,7 @@ CC32FLAGS += -m32
 KBUILD_CFLAGS := $(filter-out -mcmodel=medium -mabi=elfv1 -mabi=elfv2 -mcall-aixdesc,$(KBUILD_CFLAGS))
 endif
 
-targets := $(obj-vdso32) vdso32.so.dbg
+targets := $(obj-vdso32) vdso32.so.dbg vgettimeofday.o
 obj-vdso32 := $(addprefix $(obj)/, $(obj-vdso32))
 
 GCOV_PROFILE := n
@@ -46,9 +46,6 @@ obj-y += vdso32_wrapper.o
 targets += vdso32.lds
 CPPFLAGS_vdso32.lds += -P -C -Upowerpc
 
-# Force dependency (incbin is bad)
-$(obj)/vdso32_wrapper.o : $(obj)/vdso32.so.dbg
-
 # link rule for the .so file, .lds has to be first
 $(obj)/vdso32.so.dbg: $(src)/vdso32.lds $(obj-vdso32) $(obj)/vgettimeofday.o FORCE
 	$(call if_changed,vdso32ld_and_check)

arch/powerpc/kernel/vdso64/Makefile

@@ -17,7 +17,7 @@ endif
 
 # Build rules
 
-targets := $(obj-vdso64) vdso64.so.dbg
+targets := $(obj-vdso64) vdso64.so.dbg vgettimeofday.o
 obj-vdso64 := $(addprefix $(obj)/, $(obj-vdso64))
 
 GCOV_PROFILE := n
@@ -29,15 +29,9 @@ ccflags-y := -shared -fno-common -fno-builtin -nostdlib \
 	-Wl,-soname=linux-vdso64.so.1 -Wl,--hash-style=both
 asflags-y := -D__VDSO64__ -s
 
-obj-y += vdso64_wrapper.o
 targets += vdso64.lds
 CPPFLAGS_vdso64.lds += -P -C -U$(ARCH)
 
-$(obj)/vgettimeofday.o: %.o: %.c FORCE
-
-# Force dependency (incbin is bad)
-$(obj)/vdso64_wrapper.o : $(obj)/vdso64.so.dbg
-
 # link rule for the .so file, .lds has to be first
 $(obj)/vdso64.so.dbg: $(src)/vdso64.lds $(obj-vdso64) $(obj)/vgettimeofday.o FORCE
 	$(call if_changed,vdso64ld_and_check)

arch/powerpc/kernel/vdso64/sigtramp.S

@@ -15,11 +15,20 @@
 
 	.text
 
+/*
+ * __kernel_start_sigtramp_rt64 and __kernel_sigtramp_rt64 together
+ * are one function split in two parts. The kernel jumps to the former
+ * and the signal handler indirectly (by blr) returns to the latter.
+ * __kernel_sigtramp_rt64 needs to point to the return address so
+ * glibc can correctly identify the trampoline stack frame.
+ */
 	.balign 8
 	.balign IFETCH_ALIGN_BYTES
-V_FUNCTION_BEGIN(__kernel_sigtramp_rt64)
+V_FUNCTION_BEGIN(__kernel_start_sigtramp_rt64)
 .Lsigrt_start:
 	bctrl	/* call the handler */
+V_FUNCTION_END(__kernel_start_sigtramp_rt64)
+V_FUNCTION_BEGIN(__kernel_sigtramp_rt64)
 	addi	r1, r1, __SIGNAL_FRAMESIZE
 	li	r0,__NR_rt_sigreturn
 	sc

arch/powerpc/kernel/vdso64/vdso64.lds.S

@@ -131,4 +131,4 @@ VERSION
 /*
  * Make the sigreturn code visible to the kernel.
  */
-VDSO_sigtramp_rt64	= __kernel_sigtramp_rt64;
+VDSO_sigtramp_rt64	= __kernel_start_sigtramp_rt64;

arch/powerpc/lib/sstep.c

@@ -818,13 +818,15 @@ void emulate_vsx_store(struct instruction_op *op, const union vsx_reg *reg,
 			break;
 		if (rev) {
 			/* reverse 32 bytes */
-			buf.d[0] = byterev_8(reg->d[3]);
+			union vsx_reg buf32[2];
-			buf.d[1] = byterev_8(reg->d[2]);
+			buf32[0].d[0] = byterev_8(reg[1].d[1]);
-			buf.d[2] = byterev_8(reg->d[1]);
+			buf32[0].d[1] = byterev_8(reg[1].d[0]);
-			buf.d[3] = byterev_8(reg->d[0]);
+			buf32[1].d[0] = byterev_8(reg[0].d[1]);
-			reg = &buf;
+			buf32[1].d[1] = byterev_8(reg[0].d[0]);
+			memcpy(mem, buf32, size);
+		} else {
+			memcpy(mem, reg, size);
 		}
-		memcpy(mem, reg, size);
 		break;
 	case 16:
 		/* stxv, stxvx, stxvl, stxvll */