[PATCH] powerpc: Implement support for setting little-endian mode via prctl

This adds the PowerPC part of the code to allow processes to change
their endian mode via prctl.

This also extends the alignment exception handler to be able to fix up
alignment exceptions that occur in little-endian mode, both for
"PowerPC" little-endian and true little-endian.

We always enter signal handlers in big-endian mode -- the support for
little-endian mode does not amount to the creation of a little-endian
user/kernel ABI.  If the signal handler returns, the endian mode is
restored to what it was when the signal was delivered.

We have two new kernel CPU feature bits, one for PPC little-endian and
one for true little-endian.  Most of the classic 32-bit processors
support PPC little-endian, and this is reflected in the CPU feature
table.  There are two corresponding feature bits reported to userland
in the AT_HWCAP aux vector entry.

This is based on an earlier patch by Anton Blanchard.

Signed-off-by: Paul Mackerras <paulus@samba.org>

1 files changed, 49 insertions, 35 deletions

diff --git a/arch/powerpc/kernel/cputable.c b/arch/powerpc/kernel/cputable.c
index 83f9ab139d4..dfe2fcfb20a 100644
--- a/arch/powerpc/kernel/cputable.c
+++ b/arch/powerpc/kernel/cputable.c
@@ -54,7 +54,8 @@ extern void __setup_cpu_ppc970(unsigned long offset, struct cpu_spec* spec);
 #define COMMON_USER_POWER5_PLUS	(COMMON_USER_PPC64 | PPC_FEATURE_POWER5_PLUS|\
 				 PPC_FEATURE_SMT | PPC_FEATURE_ICACHE_SNOOP)
 #define COMMON_USER_POWER6	(COMMON_USER_PPC64 | PPC_FEATURE_ARCH_2_05 |\
-				 PPC_FEATURE_SMT | PPC_FEATURE_ICACHE_SNOOP)
+				 PPC_FEATURE_SMT | PPC_FEATURE_ICACHE_SNOOP | \
+				 PPC_FEATURE_TRUE_LE)
 #define COMMON_USER_BOOKE	(PPC_FEATURE_32 | PPC_FEATURE_HAS_MMU | \
 				 PPC_FEATURE_BOOKE)
 
@@ -74,7 +75,7 @@ struct cpu_spec	cpu_specs[] = {
 		.pvr_value		= 0x00400000,
 		.cpu_name		= "POWER3 (630)",
 		.cpu_features		= CPU_FTRS_POWER3,
-		.cpu_user_features	= COMMON_USER_PPC64,
+		.cpu_user_features	= COMMON_USER_PPC64|PPC_FEATURE_PPC_LE,
 		.icache_bsize		= 128,
 		.dcache_bsize		= 128,
 		.num_pmcs		= 8,
@@ -87,7 +88,7 @@ struct cpu_spec	cpu_specs[] = {
 		.pvr_value		= 0x00410000,
 		.cpu_name		= "POWER3 (630+)",
 		.cpu_features		= CPU_FTRS_POWER3,
-		.cpu_user_features	= COMMON_USER_PPC64,
+		.cpu_user_features	= COMMON_USER_PPC64|PPC_FEATURE_PPC_LE,
 		.icache_bsize		= 128,
 		.dcache_bsize		= 128,
 		.num_pmcs		= 8,
@@ -318,7 +319,7 @@ struct cpu_spec	cpu_specs[] = {
 		.pvr_value		= 0x00030000,
 		.cpu_name		= "603",
 		.cpu_features		= CPU_FTRS_603,
-		.cpu_user_features	= COMMON_USER,
+		.cpu_user_features	= COMMON_USER | PPC_FEATURE_PPC_LE,
 		.icache_bsize		= 32,
 		.dcache_bsize		= 32,
 		.cpu_setup		= __setup_cpu_603,
@@ -329,7 +330,7 @@ struct cpu_spec	cpu_specs[] = {
 		.pvr_value		= 0x00060000,
 		.cpu_name		= "603e",
 		.cpu_features		= CPU_FTRS_603,
-		.cpu_user_features	= COMMON_USER,
+		.cpu_user_features	= COMMON_USER | PPC_FEATURE_PPC_LE,
 		.icache_bsize		= 32,
 		.dcache_bsize		= 32,
 		.cpu_setup		= __setup_cpu_603,
@@ -340,7 +341,7 @@ struct cpu_spec	cpu_specs[] = {
 		.pvr_value		= 0x00070000,
 		.cpu_name		= "603ev",
 		.cpu_features		= CPU_FTRS_603,
-		.cpu_user_features	= COMMON_USER,
+		.cpu_user_features	= COMMON_USER | PPC_FEATURE_PPC_LE,
 		.icache_bsize		= 32,
 		.dcache_bsize		= 32,
 		.cpu_setup		= __setup_cpu_603,
@@ -351,7 +352,7 @@ struct cpu_spec	cpu_specs[] = {
 		.pvr_value		= 0x00040000,
 		.cpu_name		= "604",
 		.cpu_features		= CPU_FTRS_604,
-		.cpu_user_features	= COMMON_USER,
+		.cpu_user_features	= COMMON_USER | PPC_FEATURE_PPC_LE,
 		.icache_bsize		= 32,
 		.dcache_bsize		= 32,
 		.num_pmcs		= 2,
@@ -363,7 +364,7 @@ struct cpu_spec	cpu_specs[] = {
 		.pvr_value		= 0x00090000,
 		.cpu_name		= "604e",
 		.cpu_features		= CPU_FTRS_604,
-		.cpu_user_features	= COMMON_USER,
+		.cpu_user_features	= COMMON_USER | PPC_FEATURE_PPC_LE,
 		.icache_bsize		= 32,
 		.dcache_bsize		= 32,
 		.num_pmcs		= 4,
@@ -375,7 +376,7 @@ struct cpu_spec	cpu_specs[] = {
 		.pvr_value		= 0x00090000,
 		.cpu_name		= "604r",
 		.cpu_features		= CPU_FTRS_604,
-		.cpu_user_features	= COMMON_USER,
+		.cpu_user_features	= COMMON_USER | PPC_FEATURE_PPC_LE,
 		.icache_bsize		= 32,
 		.dcache_bsize		= 32,
 		.num_pmcs		= 4,
@@ -387,7 +388,7 @@ struct cpu_spec	cpu_specs[] = {
 		.pvr_value		= 0x000a0000,
 		.cpu_name		= "604ev",
 		.cpu_features		= CPU_FTRS_604,
-		.cpu_user_features	= COMMON_USER,
+		.cpu_user_features	= COMMON_USER | PPC_FEATURE_PPC_LE,
 		.icache_bsize		= 32,
 		.dcache_bsize		= 32,
 		.num_pmcs		= 4,
@@ -399,7 +400,7 @@ struct cpu_spec	cpu_specs[] = {
 		.pvr_value		= 0x00084202,
 		.cpu_name		= "740/750",
 		.cpu_features		= CPU_FTRS_740_NOTAU,
-		.cpu_user_features	= COMMON_USER,
+		.cpu_user_features	= COMMON_USER | PPC_FEATURE_PPC_LE,
 		.icache_bsize		= 32,
 		.dcache_bsize		= 32,
 		.num_pmcs		= 4,
@@ -411,7 +412,7 @@ struct cpu_spec	cpu_specs[] = {
 		.pvr_value		= 0x00080100,
 		.cpu_name		= "750CX",
 		.cpu_features		= CPU_FTRS_750,
-		.cpu_user_features	= COMMON_USER,
+		.cpu_user_features	= COMMON_USER | PPC_FEATURE_PPC_LE,
 		.icache_bsize		= 32,
 		.dcache_bsize		= 32,
 		.num_pmcs		= 4,
@@ -423,7 +424,7 @@ struct cpu_spec	cpu_specs[] = {
 		.pvr_value		= 0x00082200,
 		.cpu_name		= "750CX",
 		.cpu_features		= CPU_FTRS_750,
-		.cpu_user_features	= COMMON_USER,
+		.cpu_user_features	= COMMON_USER | PPC_FEATURE_PPC_LE,
 		.icache_bsize		= 32,
 		.dcache_bsize		= 32,
 		.num_pmcs		= 4,
@@ -435,7 +436,7 @@ struct cpu_spec	cpu_specs[] = {
 		.pvr_value		= 0x00082210,
 		.cpu_name		= "750CXe",
 		.cpu_features		= CPU_FTRS_750,
-		.cpu_user_features	= COMMON_USER,
+		.cpu_user_features	= COMMON_USER | PPC_FEATURE_PPC_LE,
 		.icache_bsize		= 32,
 		.dcache_bsize		= 32,
 		.num_pmcs		= 4,
@@ -447,7 +448,7 @@ struct cpu_spec	cpu_specs[] = {
 		.pvr_value		= 0x00083214,
 		.cpu_name		= "750CXe",
 		.cpu_features		= CPU_FTRS_750,
-		.cpu_user_features	= COMMON_USER,
+		.cpu_user_features	= COMMON_USER | PPC_FEATURE_PPC_LE,
 		.icache_bsize		= 32,
 		.dcache_bsize		= 32,
 		.num_pmcs		= 4,
@@ -459,7 +460,7 @@ struct cpu_spec	cpu_specs[] = {
 		.pvr_value		= 0x00083000,
 		.cpu_name		= "745/755",
 		.cpu_features		= CPU_FTRS_750,
-		.cpu_user_features	= COMMON_USER,
+		.cpu_user_features	= COMMON_USER | PPC_FEATURE_PPC_LE,
 		.icache_bsize		= 32,
 		.dcache_bsize		= 32,
 		.num_pmcs		= 4,
@@ -471,7 +472,7 @@ struct cpu_spec	cpu_specs[] = {
 		.pvr_value		= 0x70000100,
 		.cpu_name		= "750FX",
 		.cpu_features		= CPU_FTRS_750FX1,
-		.cpu_user_features	= COMMON_USER,
+		.cpu_user_features	= COMMON_USER | PPC_FEATURE_PPC_LE,
 		.icache_bsize		= 32,
 		.dcache_bsize		= 32,
 		.num_pmcs		= 4,
@@ -483,7 +484,7 @@ struct cpu_spec	cpu_specs[] = {
 		.pvr_value		= 0x70000200,
 		.cpu_name		= "750FX",
 		.cpu_features		= CPU_FTRS_750FX2,
-		.cpu_user_features	= COMMON_USER,
+		.cpu_user_features	= COMMON_USER | PPC_FEATURE_PPC_LE,
 		.icache_bsize		= 32,
 		.dcache_bsize		= 32,
 		.num_pmcs		= 4,
@@ -495,7 +496,7 @@ struct cpu_spec	cpu_specs[] = {
 		.pvr_value		= 0x70000000,
 		.cpu_name		= "750FX",
 		.cpu_features		= CPU_FTRS_750FX,
-		.cpu_user_features	= COMMON_USER,
+		.cpu_user_features	= COMMON_USER | PPC_FEATURE_PPC_LE,
 		.icache_bsize		= 32,
 		.dcache_bsize		= 32,
 		.num_pmcs		= 4,
@@ -507,7 +508,7 @@ struct cpu_spec	cpu_specs[] = {
 		.pvr_value		= 0x70020000,
 		.cpu_name		= "750GX",
 		.cpu_features		= CPU_FTRS_750GX,
-		.cpu_user_features	= COMMON_USER,
+		.cpu_user_features	= COMMON_USER | PPC_FEATURE_PPC_LE,
 		.icache_bsize		= 32,
 		.dcache_bsize		= 32,
 		.num_pmcs		= 4,
@@ -519,7 +520,7 @@ struct cpu_spec	cpu_specs[] = {
 		.pvr_value		= 0x00080000,
 		.cpu_name		= "740/750",
 		.cpu_features		= CPU_FTRS_740,
-		.cpu_user_features	= COMMON_USER,
+		.cpu_user_features	= COMMON_USER | PPC_FEATURE_PPC_LE,
 		.icache_bsize		= 32,
 		.dcache_bsize		= 32,
 		.num_pmcs		= 4,
@@ -531,7 +532,8 @@ struct cpu_spec	cpu_specs[] = {
 		.pvr_value		= 0x000c1101,
 		.cpu_name		= "7400 (1.1)",
 		.cpu_features		= CPU_FTRS_7400_NOTAU,
-		.cpu_user_features	= COMMON_USER | PPC_FEATURE_HAS_ALTIVEC_COMP,
+		.cpu_user_features	= COMMON_USER |
+			PPC_FEATURE_HAS_ALTIVEC_COMP | PPC_FEATURE_PPC_LE,
 		.icache_bsize		= 32,
 		.dcache_bsize		= 32,
 		.num_pmcs		= 4,
@@ -543,7 +545,8 @@ struct cpu_spec	cpu_specs[] = {
 		.pvr_value		= 0x000c0000,
 		.cpu_name		= "7400",
 		.cpu_features		= CPU_FTRS_7400,
-		.cpu_user_features	= COMMON_USER | PPC_FEATURE_HAS_ALTIVEC_COMP,
+		.cpu_user_features	= COMMON_USER |
+			PPC_FEATURE_HAS_ALTIVEC_COMP | PPC_FEATURE_PPC_LE,
 		.icache_bsize		= 32,
 		.dcache_bsize		= 32,
 		.num_pmcs		= 4,
@@ -555,7 +558,8 @@ struct cpu_spec	cpu_specs[] = {
 		.pvr_value		= 0x800c0000,
 		.cpu_name		= "7410",
 		.cpu_features		= CPU_FTRS_7400,
-		.cpu_user_features	= COMMON_USER | PPC_FEATURE_HAS_ALTIVEC_COMP,
+		.cpu_user_features	= COMMON_USER |
+			PPC_FEATURE_HAS_ALTIVEC_COMP | PPC_FEATURE_PPC_LE,
 		.icache_bsize		= 32,
 		.dcache_bsize		= 32,
 		.num_pmcs		= 4,
@@ -567,7 +571,8 @@ struct cpu_spec	cpu_specs[] = {
 		.pvr_value		= 0x80000200,
 		.cpu_name		= "7450",
 		.cpu_features		= CPU_FTRS_7450_20,
-		.cpu_user_features	= COMMON_USER | PPC_FEATURE_HAS_ALTIVEC_COMP,
+		.cpu_user_features	= COMMON_USER |
+			PPC_FEATURE_HAS_ALTIVEC_COMP | PPC_FEATURE_PPC_LE,
 		.icache_bsize		= 32,
 		.dcache_bsize		= 32,
 		.num_pmcs		= 6,
@@ -581,7 +586,8 @@ struct cpu_spec	cpu_specs[] = {
 		.pvr_value		= 0x80000201,
 		.cpu_name		= "7450",
 		.cpu_features		= CPU_FTRS_7450_21,
-		.cpu_user_features	= COMMON_USER | PPC_FEATURE_HAS_ALTIVEC_COMP,
+		.cpu_user_features	= COMMON_USER |
+			PPC_FEATURE_HAS_ALTIVEC_COMP | PPC_FEATURE_PPC_LE,
 		.icache_bsize		= 32,
 		.dcache_bsize		= 32,
 		.num_pmcs		= 6,
@@ -595,7 +601,8 @@ struct cpu_spec	cpu_specs[] = {
 		.pvr_value		= 0x80000000,
 		.cpu_name		= "7450",
 		.cpu_features		= CPU_FTRS_7450_23,
-		.cpu_user_features	= COMMON_USER | PPC_FEATURE_HAS_ALTIVEC_COMP,
+		.cpu_user_features	= COMMON_USER |
+			PPC_FEATURE_HAS_ALTIVEC_COMP | PPC_FEATURE_PPC_LE,
 		.icache_bsize		= 32,
 		.dcache_bsize		= 32,
 		.num_pmcs		= 6,
@@ -609,7 +616,8 @@ struct cpu_spec	cpu_specs[] = {
 		.pvr_value		= 0x80010100,
 		.cpu_name		= "7455",
 		.cpu_features		= CPU_FTRS_7455_1,
-		.cpu_user_features	= COMMON_USER | PPC_FEATURE_HAS_ALTIVEC_COMP,
+		.cpu_user_features	= COMMON_USER |
+			PPC_FEATURE_HAS_ALTIVEC_COMP | PPC_FEATURE_PPC_LE,
 		.icache_bsize		= 32,
 		.dcache_bsize		= 32,
 		.num_pmcs		= 6,
@@ -623,7 +631,8 @@ struct cpu_spec	cpu_specs[] = {
 		.pvr_value		= 0x80010200,
 		.cpu_name		= "7455",
 		.cpu_features		= CPU_FTRS_7455_20,
-		.cpu_user_features	= COMMON_USER | PPC_FEATURE_HAS_ALTIVEC_COMP,
+		.cpu_user_features	= COMMON_USER |
+			PPC_FEATURE_HAS_ALTIVEC_COMP | PPC_FEATURE_PPC_LE,
 		.icache_bsize		= 32,
 		.dcache_bsize		= 32,
 		.num_pmcs		= 6,
@@ -637,7 +646,8 @@ struct cpu_spec	cpu_specs[] = {
 		.pvr_value		= 0x80010000,
 		.cpu_name		= "7455",
 		.cpu_features		= CPU_FTRS_7455,
-		.cpu_user_features	= COMMON_USER | PPC_FEATURE_HAS_ALTIVEC_COMP,
+		.cpu_user_features	= COMMON_USER |
+			PPC_FEATURE_HAS_ALTIVEC_COMP | PPC_FEATURE_PPC_LE,
 		.icache_bsize		= 32,
 		.dcache_bsize		= 32,
 		.num_pmcs		= 6,
@@ -651,7 +661,8 @@ struct cpu_spec	cpu_specs[] = {
 		.pvr_value		= 0x80020100,
 		.cpu_name		= "7447/7457",
 		.cpu_features		= CPU_FTRS_7447_10,
-		.cpu_user_features	= COMMON_USER | PPC_FEATURE_HAS_ALTIVEC_COMP,
+		.cpu_user_features	= COMMON_USER |
+			PPC_FEATURE_HAS_ALTIVEC_COMP | PPC_FEATURE_PPC_LE,
 		.icache_bsize		= 32,
 		.dcache_bsize		= 32,
 		.num_pmcs		= 6,
@@ -665,7 +676,8 @@ struct cpu_spec	cpu_specs[] = {
 		.pvr_value		= 0x80020101,
 		.cpu_name		= "7447/7457",
 		.cpu_features		= CPU_FTRS_7447_10,
-		.cpu_user_features	= COMMON_USER | PPC_FEATURE_HAS_ALTIVEC_COMP,
+		.cpu_user_features	= COMMON_USER |
+			PPC_FEATURE_HAS_ALTIVEC_COMP | PPC_FEATURE_PPC_LE,
 		.icache_bsize		= 32,
 		.dcache_bsize		= 32,
 		.num_pmcs		= 6,
@@ -679,7 +691,7 @@ struct cpu_spec	cpu_specs[] = {
 		.pvr_value		= 0x80020000,
 		.cpu_name		= "7447/7457",
 		.cpu_features		= CPU_FTRS_7447,
-		.cpu_user_features	= COMMON_USER | PPC_FEATURE_HAS_ALTIVEC_COMP,
+		.cpu_user_features	= COMMON_USER | PPC_FEATURE_HAS_ALTIVEC_COMP | PPC_FEATURE_PPC_LE,
 		.icache_bsize		= 32,
 		.dcache_bsize		= 32,
 		.num_pmcs		= 6,
@@ -693,7 +705,8 @@ struct cpu_spec	cpu_specs[] = {
 		.pvr_value		= 0x80030000,
 		.cpu_name		= "7447A",
 		.cpu_features		= CPU_FTRS_7447A,
-		.cpu_user_features	= COMMON_USER | PPC_FEATURE_HAS_ALTIVEC_COMP,
+		.cpu_user_features	= COMMON_USER |
+			PPC_FEATURE_HAS_ALTIVEC_COMP | PPC_FEATURE_PPC_LE,
 		.icache_bsize		= 32,
 		.dcache_bsize		= 32,
 		.num_pmcs		= 6,
@@ -707,7 +720,8 @@ struct cpu_spec	cpu_specs[] = {
 		.pvr_value		= 0x80040000,
 		.cpu_name		= "7448",
 		.cpu_features		= CPU_FTRS_7447A,
-		.cpu_user_features	= COMMON_USER | PPC_FEATURE_HAS_ALTIVEC_COMP,
+		.cpu_user_features	= COMMON_USER |
+			PPC_FEATURE_HAS_ALTIVEC_COMP | PPC_FEATURE_PPC_LE,
 		.icache_bsize		= 32,
 		.dcache_bsize		= 32,
 		.num_pmcs		= 6,