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powerpc: Save Come-From Address Register (CFAR) in exception frame

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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>
This commit is contained in:
Paul Mackerras 2011-05-01 19:48:20 +00:00 committed by Benjamin Herrenschmidt
parent 1977b50212
commit 48404f2e95
6 changed files with 24 additions and 5 deletions
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5
arch/powerpc/include/asm/cputable.h
View File

@ -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 | \

9
arch/powerpc/include/asm/exception-64s.h
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@ -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); \

6
arch/powerpc/include/asm/paca.h
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@ -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;

1
arch/powerpc/include/asm/reg.h
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@ -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

4
arch/powerpc/kernel/exceptions-64s.S
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@ -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)

4
arch/powerpc/xmon/xmon.c
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@ -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);