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authorPaul Mackerras <paulus@samba.org>2011-05-01 19:48:20 +0000
committerBenjamin Herrenschmidt <benh@kernel.crashing.org>2011-05-04 15:22:09 +1000
commit48404f2e95ef0ffd8134d89c8abcd1a15e15f1b0 (patch)
treec1f55c2b59f4c32848152a4bdc23aac8537b8cbb
parent1977b502120d44b9b4897703adfb2e2fab346880 (diff)
downloadlinaro-lsk-48404f2e95ef0ffd8134d89c8abcd1a15e15f1b0.tar.gz
powerpc: Save Come-From Address Register (CFAR) in exception frame
Recent 64-bit server processors (POWER6 and POWER7) have a "Come-From Address Register" (CFAR), that records the address of the most recent branch or rfid (return from interrupt) instruction for debugging purposes. This saves the value of the CFAR in the exception entry code and stores it in the exception frame. We also make xmon print the CFAR value in its register dump code. Rather than extend the pt_regs struct at this time, we steal the orig_gpr3 field, which is only used for system calls, and use it for the CFAR value for all exceptions/interrupts other than system calls. This means we don't save the CFAR on system calls, which is not a great problem since system calls tend not to happen unexpectedly, and also avoids adding the overhead of reading the CFAR to the system call entry path. Signed-off-by: Paul Mackerras <paulus@samba.org> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
-rw-r--r--arch/powerpc/include/asm/cputable.h5
-rw-r--r--arch/powerpc/include/asm/exception-64s.h9
-rw-r--r--arch/powerpc/include/asm/paca.h6
-rw-r--r--arch/powerpc/include/asm/reg.h1
-rw-r--r--arch/powerpc/kernel/exceptions-64s.S4
-rw-r--r--arch/powerpc/xmon/xmon.c4
6 files changed, 24 insertions, 5 deletions
diff --git a/arch/powerpc/include/asm/cputable.h b/arch/powerpc/include/asm/cputable.h
index a3e1a9e96a7..4efbfb3f325 100644
--- a/arch/powerpc/include/asm/cputable.h
+++ b/arch/powerpc/include/asm/cputable.h
@@ -180,6 +180,7 @@ extern const char *powerpc_base_platform;
#define CPU_FTR_HVMODE_206 LONG_ASM_CONST(0x0000000800000000)
+#define CPU_FTR_CFAR LONG_ASM_CONST(0x0000001000000000)
#define CPU_FTR_IABR LONG_ASM_CONST(0x0000002000000000)
#define CPU_FTR_MMCRA LONG_ASM_CONST(0x0000004000000000)
#define CPU_FTR_CTRL LONG_ASM_CONST(0x0000008000000000)
@@ -412,7 +413,7 @@ extern const char *powerpc_base_platform;
CPU_FTR_COHERENT_ICACHE | \
CPU_FTR_PURR | CPU_FTR_SPURR | CPU_FTR_REAL_LE | \
CPU_FTR_DSCR | CPU_FTR_UNALIGNED_LD_STD | \
- CPU_FTR_STCX_CHECKS_ADDRESS | CPU_FTR_POPCNTB)
+ CPU_FTR_STCX_CHECKS_ADDRESS | CPU_FTR_POPCNTB | CPU_FTR_CFAR)
#define CPU_FTRS_POWER7 (CPU_FTR_USE_TB | CPU_FTR_LWSYNC | \
CPU_FTR_PPCAS_ARCH_V2 | CPU_FTR_CTRL | CPU_FTR_HVMODE_206 |\
CPU_FTR_MMCRA | CPU_FTR_SMT | \
@@ -420,7 +421,7 @@ extern const char *powerpc_base_platform;
CPU_FTR_PURR | CPU_FTR_SPURR | CPU_FTR_REAL_LE | \
CPU_FTR_DSCR | CPU_FTR_SAO | CPU_FTR_ASYM_SMT | \
CPU_FTR_STCX_CHECKS_ADDRESS | CPU_FTR_POPCNTB | CPU_FTR_POPCNTD | \
- CPU_FTR_ICSWX)
+ CPU_FTR_ICSWX | CPU_FTR_CFAR)
#define CPU_FTRS_CELL (CPU_FTR_USE_TB | CPU_FTR_LWSYNC | \
CPU_FTR_PPCAS_ARCH_V2 | CPU_FTR_CTRL | \
CPU_FTR_ALTIVEC_COMP | CPU_FTR_MMCRA | CPU_FTR_SMT | \
diff --git a/arch/powerpc/include/asm/exception-64s.h b/arch/powerpc/include/asm/exception-64s.h
index 96ccef136ca..f5dfe3411f6 100644
--- a/arch/powerpc/include/asm/exception-64s.h
+++ b/arch/powerpc/include/asm/exception-64s.h
@@ -46,6 +46,7 @@
#define EX_CCR 60
#define EX_R3 64
#define EX_LR 72
+#define EX_CFAR 80
/*
* We're short on space and time in the exception prolog, so we can't
@@ -66,6 +67,10 @@
std r10,area+EX_R10(r13); \
std r11,area+EX_R11(r13); \
std r12,area+EX_R12(r13); \
+ BEGIN_FTR_SECTION_NESTED(66); \
+ mfspr r10,SPRN_CFAR; \
+ std r10,area+EX_CFAR(r13); \
+ END_FTR_SECTION_NESTED(CPU_FTR_CFAR, CPU_FTR_CFAR, 66); \
GET_SCRATCH0(r9); \
std r9,area+EX_R13(r13); \
mfcr r9
@@ -130,6 +135,10 @@
std r9,GPR11(r1); \
std r10,GPR12(r1); \
std r11,GPR13(r1); \
+ BEGIN_FTR_SECTION_NESTED(66); \
+ ld r10,area+EX_CFAR(r13); \
+ std r10,ORIG_GPR3(r1); \
+ END_FTR_SECTION_NESTED(CPU_FTR_CFAR, CPU_FTR_CFAR, 66); \
ld r2,PACATOC(r13); /* get kernel TOC into r2 */ \
mflr r9; /* save LR in stackframe */ \
std r9,_LINK(r1); \
diff --git a/arch/powerpc/include/asm/paca.h b/arch/powerpc/include/asm/paca.h
index 65c13c48db4..74126765106 100644
--- a/arch/powerpc/include/asm/paca.h
+++ b/arch/powerpc/include/asm/paca.h
@@ -92,9 +92,9 @@ struct paca_struct {
* Now, starting in cacheline 2, the exception save areas
*/
/* used for most interrupts/exceptions */
- u64 exgen[10] __attribute__((aligned(0x80)));
- u64 exmc[10]; /* used for machine checks */
- u64 exslb[10]; /* used for SLB/segment table misses
+ u64 exgen[11] __attribute__((aligned(0x80)));
+ u64 exmc[11]; /* used for machine checks */
+ u64 exslb[11]; /* used for SLB/segment table misses
* on the linear mapping */
/* SLB related definitions */
u16 vmalloc_sllp;
diff --git a/arch/powerpc/include/asm/reg.h b/arch/powerpc/include/asm/reg.h
index 632e78e1444..fdec5933305 100644
--- a/arch/powerpc/include/asm/reg.h
+++ b/arch/powerpc/include/asm/reg.h
@@ -188,6 +188,7 @@
#define SPRN_CTR 0x009 /* Count Register */
#define SPRN_DSCR 0x11
+#define SPRN_CFAR 0x1c /* Come From Address Register */
#define SPRN_ACOP 0x1F /* Available Coprocessor Register */
#define SPRN_CTRLF 0x088
#define SPRN_CTRLT 0x098
diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S
index 27ca8b7c600..0ec3b42717d 100644
--- a/arch/powerpc/kernel/exceptions-64s.S
+++ b/arch/powerpc/kernel/exceptions-64s.S
@@ -474,6 +474,10 @@ bad_stack:
std r9,GPR11(r1)
std r10,GPR12(r1)
std r11,GPR13(r1)
+BEGIN_FTR_SECTION
+ ld r10,EX_CFAR(r3)
+ std r10,ORIG_GPR3(r1)
+END_FTR_SECTION_IFSET(CPU_FTR_CFAR)
SAVE_8GPRS(14,r1)
SAVE_10GPRS(22,r1)
lhz r12,PACA_TRAP_SAVE(r13)
diff --git a/arch/powerpc/xmon/xmon.c b/arch/powerpc/xmon/xmon.c
index 60593ad861e..909804aaeeb 100644
--- a/arch/powerpc/xmon/xmon.c
+++ b/arch/powerpc/xmon/xmon.c
@@ -1497,6 +1497,10 @@ static void prregs(struct pt_regs *fp)
#endif
printf("pc = ");
xmon_print_symbol(fp->nip, " ", "\n");
+ if (TRAP(fp) != 0xc00 && cpu_has_feature(CPU_FTR_CFAR)) {
+ printf("cfar= ");
+ xmon_print_symbol(fp->orig_gpr3, " ", "\n");
+ }
printf("lr = ");
xmon_print_symbol(fp->link, " ", "\n");
printf("msr = "REG" cr = %.8lx\n", fp->msr, fp->ccr);