diff mbox series

[v3,2/2] xen/ppc: Implement a basic exception handler

Message ID 1d875c978caa4ed0b3d038655a39aa0cb0583565.1698273423.git.sanastasio@raptorengineering.com (mailing list archive)
State New, archived
Headers show
Series Early exception handlers on Power | expand

Commit Message

Shawn Anastasio Oct. 25, 2023, 10:41 p.m. UTC
Implement a basic exception handler that dumps the CPU state to the
console, as well as the code required to set the correct exception
vector table's base address in setup.c.

Signed-off-by: Shawn Anastasio <sanastasio@raptorengineering.com>
---
v3:
  - Add comment to explain %r1 clobber
  - Add comment about ISR declaration order
  - Drop redundant " Interrupt" from exception name strings

v2:
  - Place {h_,}exception_common in .text.exceptions section
  - Use assembler macro instead of CPP macro for ISR definition
  - Tabulate ISR definitions

 xen/arch/ppc/include/asm/processor.h |  31 +++++++
 xen/arch/ppc/ppc64/Makefile          |   2 +
 xen/arch/ppc/ppc64/asm-offsets.c     |   1 +
 xen/arch/ppc/ppc64/exceptions-asm.S  | 129 +++++++++++++++++++++++++++
 xen/arch/ppc/ppc64/exceptions.c      | 102 +++++++++++++++++++++
 xen/arch/ppc/setup.c                 |  11 +++
 6 files changed, 276 insertions(+)
 create mode 100644 xen/arch/ppc/ppc64/exceptions-asm.S
 create mode 100644 xen/arch/ppc/ppc64/exceptions.c

--
2.30.2

Comments

Jan Beulich Oct. 26, 2023, 8:03 a.m. UTC | #1
On 26.10.2023 00:41, Shawn Anastasio wrote:
> Implement a basic exception handler that dumps the CPU state to the
> console, as well as the code required to set the correct exception
> vector table's base address in setup.c.
> 
> Signed-off-by: Shawn Anastasio <sanastasio@raptorengineering.com>

Despite me being unhappy about the disconnect of the constants
Acked-by: Jan Beulich <jbeulich@suse.com>
One further remark/suggestion though (happy to take care of while
committing):

> --- /dev/null
> +++ b/xen/arch/ppc/ppc64/exceptions-asm.S
> @@ -0,0 +1,135 @@
> +/* SPDX-License-Identifier: GPL-2.0-or-later */
> +
> +#include <asm/asm-defns.h>
> +#include <asm/processor.h>
> +
> +    .section .text.exceptions, "ax", %progbits
> +
> +    /* Helper to dump CPU state to struct cpu_user_regs pointed to by r1. */
> +ENTRY(exception_common)
> +    /*
> +     * Save GPRs 1-31. TODO: The value of %r1 has already been modified by the
> +     * ISR, so the value we save isn't the exact value we had on entry.
> +     */
> +    SAVE_GPRS(1, 31, %r1)

Wouldn't this comment ...

> +    /* Save LR, CTR, CR */
> +    mflr    %r0
> +    std     %r0, UREGS_lr(%r1)
> +    mfctr   %r0
> +    std     %r0, UREGS_ctr(%r1)
> +    mfcr    %r0
> +    stw     %r0, UREGS_cr(%r1) /* 32-bit */
> +
> +    /* Save Exception Registers */
> +    mfsrr0  %r0
> +    std     %r0, UREGS_pc(%r1)
> +    mfsrr1  %r0
> +    std     %r0, UREGS_msr(%r1)
> +    mfdsisr %r0
> +    stw     %r0, UREGS_dsisr(%r1) /* 32-bit */
> +    mfdar   %r0
> +    std     %r0, UREGS_dar(%r1)
> +    li      %r0, -1 /* OS's SRR0/SRR1 have been clobbered */
> +    std     %r0, UREGS_srr0(%r1)
> +    std     %r0, UREGS_srr1(%r1)
> +
> +    /* Setup TOC and a stack frame then call C exception handler */
> +    mr      %r3, %r1
> +    bcl     20, 31, 1f
> +1:  mflr    %r12
> +    addis   %r2, %r12, .TOC.-1b@ha
> +    addi    %r2, %r2, .TOC.-1b@l
> +
> +    li      %r0, 0
> +    stdu    %r0, -STACK_FRAME_OVERHEAD(%r1)
> +    bl      exception_handler
> +
> +    .size exception_common, . - exception_common
> +    .type exception_common, %function
> +
> +    /* Same as exception_common, but for exceptions that set HSRR{0,1} */
> +ENTRY(h_exception_common)
> +    /* Save GPRs 1-31 */
> +    SAVE_GPRS(1, 31, %r1)

... better be repeated here?

Jan
Shawn Anastasio Oct. 26, 2023, 6:40 p.m. UTC | #2
On 10/26/23 3:03 AM, Jan Beulich wrote:
> On 26.10.2023 00:41, Shawn Anastasio wrote:
>> Implement a basic exception handler that dumps the CPU state to the
>> console, as well as the code required to set the correct exception
>> vector table's base address in setup.c.
>>
>> Signed-off-by: Shawn Anastasio <sanastasio@raptorengineering.com>
> 
> Despite me being unhappy about the disconnect of the constants
> Acked-by: Jan Beulich <jbeulich@suse.com>
> One further remark/suggestion though (happy to take care of while
> committing):
> 
>> --- /dev/null
>> +++ b/xen/arch/ppc/ppc64/exceptions-asm.S
>> @@ -0,0 +1,135 @@
>> +/* SPDX-License-Identifier: GPL-2.0-or-later */
>> +
>> +#include <asm/asm-defns.h>
>> +#include <asm/processor.h>
>> +
>> +    .section .text.exceptions, "ax", %progbits
>> +
>> +    /* Helper to dump CPU state to struct cpu_user_regs pointed to by r1. */
>> +ENTRY(exception_common)
>> +    /*
>> +     * Save GPRs 1-31. TODO: The value of %r1 has already been modified by the
>> +     * ISR, so the value we save isn't the exact value we had on entry.
>> +     */
>> +    SAVE_GPRS(1, 31, %r1)
> 
> Wouldn't this comment ...
> 
>> +    /* Save LR, CTR, CR */
>> +    mflr    %r0
>> +    std     %r0, UREGS_lr(%r1)
>> +    mfctr   %r0
>> +    std     %r0, UREGS_ctr(%r1)
>> +    mfcr    %r0
>> +    stw     %r0, UREGS_cr(%r1) /* 32-bit */
>> +
>> +    /* Save Exception Registers */
>> +    mfsrr0  %r0
>> +    std     %r0, UREGS_pc(%r1)
>> +    mfsrr1  %r0
>> +    std     %r0, UREGS_msr(%r1)
>> +    mfdsisr %r0
>> +    stw     %r0, UREGS_dsisr(%r1) /* 32-bit */
>> +    mfdar   %r0
>> +    std     %r0, UREGS_dar(%r1)
>> +    li      %r0, -1 /* OS's SRR0/SRR1 have been clobbered */
>> +    std     %r0, UREGS_srr0(%r1)
>> +    std     %r0, UREGS_srr1(%r1)
>> +
>> +    /* Setup TOC and a stack frame then call C exception handler */
>> +    mr      %r3, %r1
>> +    bcl     20, 31, 1f
>> +1:  mflr    %r12
>> +    addis   %r2, %r12, .TOC.-1b@ha
>> +    addi    %r2, %r2, .TOC.-1b@l
>> +
>> +    li      %r0, 0
>> +    stdu    %r0, -STACK_FRAME_OVERHEAD(%r1)
>> +    bl      exception_handler
>> +
>> +    .size exception_common, . - exception_common
>> +    .type exception_common, %function
>> +
>> +    /* Same as exception_common, but for exceptions that set HSRR{0,1} */
>> +ENTRY(h_exception_common)
>> +    /* Save GPRs 1-31 */
>> +    SAVE_GPRS(1, 31, %r1)
> 
> ... better be repeated here?
>

Sure, if you'd like to make that change during commit that'd be great.

> Jan

Thanks,
Shawn
diff mbox series

Patch

diff --git a/xen/arch/ppc/include/asm/processor.h b/xen/arch/ppc/include/asm/processor.h
index d3dd943c20..a01b62b8a4 100644
--- a/xen/arch/ppc/include/asm/processor.h
+++ b/xen/arch/ppc/include/asm/processor.h
@@ -103,6 +103,37 @@ 
 #define PVR_BE        0x0070
 #define PVR_PA6T      0x0090

+/* Exception Definitions */
+#define EXC_SYSTEM_RESET    0x0100 /* System Reset Interrupt */
+#define EXC_MACHINE_CHECK   0x0200 /* Machine Check Interrupt */
+#define EXC_DATA_STORAGE    0x0300 /* Data Storage Interrupt */
+#define EXC_DATA_SEGMENT    0x0380 /* Data Segment Interrupt */
+#define EXC_INSN_STORAGE    0x0400 /* Instruction Storage Interrupt */
+#define EXC_INSN_SEGMENT    0x0480 /* Instruction Segment Interrupt */
+#define EXC_EXTERNAL        0x0500 /* External Interrupt */
+#define EXC_ALIGNMENT       0x0600 /* Alignment Interrupt */
+#define EXC_PROGRAM         0x0700 /* Program Interrupt */
+#define EXC_FPU_UNAVAIL     0x0800 /* Floating-Point Unavailable Interrupt */
+#define EXC_DECREMENTER     0x0900 /* Decrementer Interrupt */
+#define EXC_H_DECREMENTER   0x0980 /* Hypervisor Decrementer Interrupt */
+#define EXC_PRIV_DOORBELL   0x0A00 /* Directed Privileged Doorbell Interrupt */
+#define EXC_SYSTEM_CALL     0x0C00 /* System Call Interrupt */
+#define EXC_TRACE           0x0D00 /* Trace Interrupt */
+#define EXC_H_DATA_STORAGE  0x0E00 /* Hypervisor Data Storage Interrupt */
+#define EXC_H_INSN_STORAGE  0x0E20 /* Hypervisor Instruction Storage Interrupt */
+#define EXC_H_EMUL_ASST     0x0E40 /* Hypervisor Emulation Assistance Interrupt */
+#define EXC_H_MAINTENANCE   0x0E60 /* Hypervisor Maintenance Interrupt */
+#define EXC_H_DOORBELL      0x0E80 /* Directed Hypervisor Doorbell Interrupt */
+#define EXC_H_VIRT          0x0EA0 /* Hypervisor Virtualization Interrupt */
+#define EXC_PERF_MON        0x0F00 /* Performance Monitor Interrupt */
+#define EXC_VECTOR_UNAVAIL  0x0F20 /* Vector Unavailable Interrupt */
+#define EXC_VSX_UNAVAIL     0x0F40 /* VSX Unavailable Interrupt */
+#define EXC_FACIL_UNAVAIL   0x0F60 /* Facility Unavailable Interrupt */
+#define EXC_H_FACIL_UNAVAIL 0x0F80 /* Hypervisor Facility Unavailable Interrupt */
+
+/* Base address of interrupt vector table when LPCR[AIL]=3 */
+#define AIL_VECTOR_BASE _AC(0xc000000000004000, UL)
+
 #ifndef __ASSEMBLY__

 #include <xen/types.h>
diff --git a/xen/arch/ppc/ppc64/Makefile b/xen/arch/ppc/ppc64/Makefile
index 5b88355bb2..914bb21c40 100644
--- a/xen/arch/ppc/ppc64/Makefile
+++ b/xen/arch/ppc/ppc64/Makefile
@@ -1,2 +1,4 @@ 
+obj-y += exceptions.o
+obj-y += exceptions-asm.o
 obj-y += head.o
 obj-y += opal-calls.o
diff --git a/xen/arch/ppc/ppc64/asm-offsets.c b/xen/arch/ppc/ppc64/asm-offsets.c
index c15c1bf136..634d7260e3 100644
--- a/xen/arch/ppc/ppc64/asm-offsets.c
+++ b/xen/arch/ppc/ppc64/asm-offsets.c
@@ -46,6 +46,7 @@  void __dummy__(void)
     OFFSET(UREGS_dsisr, struct cpu_user_regs, dsisr);
     OFFSET(UREGS_cr, struct cpu_user_regs, cr);
     OFFSET(UREGS_fpscr, struct cpu_user_regs, fpscr);
+    OFFSET(UREGS_entry_vector, struct cpu_user_regs, entry_vector);
     DEFINE(UREGS_sizeof, sizeof(struct cpu_user_regs));

     OFFSET(OPAL_base, struct opal, base);
diff --git a/xen/arch/ppc/ppc64/exceptions-asm.S b/xen/arch/ppc/ppc64/exceptions-asm.S
new file mode 100644
index 0000000000..f1b14bb860
--- /dev/null
+++ b/xen/arch/ppc/ppc64/exceptions-asm.S
@@ -0,0 +1,135 @@ 
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+
+#include <asm/asm-defns.h>
+#include <asm/processor.h>
+
+    .section .text.exceptions, "ax", %progbits
+
+    /* Helper to dump CPU state to struct cpu_user_regs pointed to by r1. */
+ENTRY(exception_common)
+    /*
+     * Save GPRs 1-31. TODO: The value of %r1 has already been modified by the
+     * ISR, so the value we save isn't the exact value we had on entry.
+     */
+    SAVE_GPRS(1, 31, %r1)
+
+    /* Save LR, CTR, CR */
+    mflr    %r0
+    std     %r0, UREGS_lr(%r1)
+    mfctr   %r0
+    std     %r0, UREGS_ctr(%r1)
+    mfcr    %r0
+    stw     %r0, UREGS_cr(%r1) /* 32-bit */
+
+    /* Save Exception Registers */
+    mfsrr0  %r0
+    std     %r0, UREGS_pc(%r1)
+    mfsrr1  %r0
+    std     %r0, UREGS_msr(%r1)
+    mfdsisr %r0
+    stw     %r0, UREGS_dsisr(%r1) /* 32-bit */
+    mfdar   %r0
+    std     %r0, UREGS_dar(%r1)
+    li      %r0, -1 /* OS's SRR0/SRR1 have been clobbered */
+    std     %r0, UREGS_srr0(%r1)
+    std     %r0, UREGS_srr1(%r1)
+
+    /* Setup TOC and a stack frame then call C exception handler */
+    mr      %r3, %r1
+    bcl     20, 31, 1f
+1:  mflr    %r12
+    addis   %r2, %r12, .TOC.-1b@ha
+    addi    %r2, %r2, .TOC.-1b@l
+
+    li      %r0, 0
+    stdu    %r0, -STACK_FRAME_OVERHEAD(%r1)
+    bl      exception_handler
+
+    .size exception_common, . - exception_common
+    .type exception_common, %function
+
+    /* Same as exception_common, but for exceptions that set HSRR{0,1} */
+ENTRY(h_exception_common)
+    /* Save GPRs 1-31 */
+    SAVE_GPRS(1, 31, %r1)
+
+    /* Save LR, CTR, CR */
+    mflr    %r0
+    std     %r0, UREGS_lr(%r1)
+    mfctr   %r0
+    std     %r0, UREGS_ctr(%r1)
+    mfcr    %r0
+    stw     %r0, UREGS_cr(%r1) /* 32-bit */
+
+    /* Save Exception Registers */
+    mfhsrr0 %r0
+    std     %r0, UREGS_pc(%r1)
+    mfhsrr1 %r0
+    std     %r0, UREGS_msr(%r1)
+    mfsrr0  %r0
+    std     %r0, UREGS_srr0(%r1)
+    mfsrr1  %r0
+    std     %r0, UREGS_srr1(%r1)
+    mfdsisr %r0
+    stw     %r0, UREGS_dsisr(%r1) /* 32-bit */
+    mfdar   %r0
+    std     %r0, UREGS_dar(%r1)
+
+    /* Setup TOC and a stack frame then call C exception handler */
+    mr      %r3, %r1
+    bcl     20, 31, 1f
+1:  mflr    %r12
+    addis   %r2, %r12, .TOC.-1b@ha
+    addi    %r2, %r2, .TOC.-1b@l
+
+    li      %r0, 0
+    stdu    %r0, -STACK_FRAME_OVERHEAD(%r1)
+    bl      exception_handler
+
+    .size h_exception_common, . - h_exception_common
+    .type h_exception_common, %function
+
+/*
+ * Declare an ISR for the provided exception that jumps to the specified handler
+ */
+.macro ISR name, exc, handler
+    . = (AIL_VECTOR_BASE - EXCEPTION_VECTORS_START) + \exc
+    ENTRY(\name)
+    /* TODO: switch stack */
+
+    /* Reserve space for struct cpu_user_regs */
+    subi    %r1, %r1, UREGS_sizeof
+
+    /* Save r0 immediately so we can use it as scratch space */
+    SAVE_GPR(0, %r1)
+
+    /* Save exception vector number */
+    li      %r0, \exc
+    std     %r0, UREGS_entry_vector(%r1)
+
+    /* Branch to common code */
+    b       \handler
+
+    .size \name, . - \name
+    .type \name, %function
+.endm
+
+/*
+ * Define all ISRs. Note: These must be declared in order from lowest exception
+ * vector to highest to satisfy the assembler.
+ */
+ISR exc_sysreset,   EXC_SYSTEM_RESET,   exception_common
+ISR exc_mcheck,     EXC_MACHINE_CHECK,  exception_common
+ISR exc_dstore,     EXC_DATA_STORAGE,   exception_common
+ISR exc_dsegment,   EXC_DATA_SEGMENT,   exception_common
+ISR exc_istore,     EXC_INSN_STORAGE,   exception_common
+ISR exc_isegment,   EXC_INSN_SEGMENT,   exception_common
+ISR exc_extern,     EXC_EXTERNAL,       exception_common
+ISR exc_align,      EXC_ALIGNMENT,      exception_common
+ISR exc_program,    EXC_PROGRAM,        exception_common
+ISR exc_fpu,        EXC_FPU_UNAVAIL,    exception_common
+ISR exc_dec,        EXC_DECREMENTER,    exception_common
+ISR exc_h_dec,      EXC_H_DECREMENTER,  h_exception_common
+/* EXC_PRIV_DOORBELL ... EXC_TRACE */
+ISR exc_h_dstore,   EXC_H_DATA_STORAGE, h_exception_common
+ISR exc_h_istore,   EXC_H_INSN_STORAGE, h_exception_common
diff --git a/xen/arch/ppc/ppc64/exceptions.c b/xen/arch/ppc/ppc64/exceptions.c
new file mode 100644
index 0000000000..c6a11c8639
--- /dev/null
+++ b/xen/arch/ppc/ppc64/exceptions.c
@@ -0,0 +1,102 @@ 
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+#include <xen/lib.h>
+
+#include <asm/processor.h>
+
+static const char *exception_name_from_vec(uint32_t vec)
+{
+    switch ( vec )
+    {
+    case EXC_SYSTEM_RESET:
+        return "System Reset";
+    case EXC_MACHINE_CHECK:
+        return "Machine Check";
+    case EXC_DATA_STORAGE:
+        return "Data Storage";
+    case EXC_DATA_SEGMENT:
+        return "Data Segment";
+    case EXC_INSN_STORAGE:
+        return "Instruction Storage";
+    case EXC_INSN_SEGMENT:
+        return "Instruction Segment";
+    case EXC_EXTERNAL:
+        return "External";
+    case EXC_ALIGNMENT:
+        return "Alignment";
+    case EXC_PROGRAM:
+        return "Program";
+    case EXC_FPU_UNAVAIL:
+        return "Floating-Point Unavailable";
+    case EXC_DECREMENTER:
+        return "Decrementer";
+    case EXC_H_DECREMENTER:
+        return "Hypervisor Decrementer";
+    case EXC_PRIV_DOORBELL:
+        return "Directed Privileged Doorbell";
+    case EXC_SYSTEM_CALL:
+        return "System Call";
+    case EXC_TRACE:
+        return "Trace";
+    case EXC_H_DATA_STORAGE:
+        return "Hypervisor Data Storage";
+    case EXC_H_INSN_STORAGE:
+        return "Hypervisor Instruction Storage";
+    case EXC_H_EMUL_ASST:
+        return "Hypervisor Emulation Assistance";
+    case EXC_H_MAINTENANCE:
+        return "Hypervisor Maintenance";
+    case EXC_H_DOORBELL:
+        return "Directed Hypervisor Doorbell";
+    case EXC_H_VIRT:
+        return "Hypervisor Virtualization";
+    case EXC_PERF_MON:
+        return "Performance Monitor";
+    case EXC_VECTOR_UNAVAIL:
+        return "Vector Unavailable";
+    case EXC_VSX_UNAVAIL:
+        return "VSX Unavailable";
+    case EXC_FACIL_UNAVAIL:
+        return "Facility Unavailable";
+    case EXC_H_FACIL_UNAVAIL:
+        return "Hypervisor Facility Unavailable";
+    default:
+        return "(unknown)";
+    }
+}
+
+void exception_handler(struct cpu_user_regs *regs)
+{
+    /* TODO: this is currently only useful for debugging */
+
+    printk("UNRECOVERABLE EXCEPTION: %s (0x%04x)\n\n"
+           "GPR 0-3   : 0x%016lx 0x%016lx 0x%016lx 0x%016lx\n"
+           "GPR 4-7   : 0x%016lx 0x%016lx 0x%016lx 0x%016lx\n"
+           "GPR 8-11  : 0x%016lx 0x%016lx 0x%016lx 0x%016lx\n"
+           "GPR 12-15 : 0x%016lx 0x%016lx 0x%016lx 0x%016lx\n"
+           "GPR 16-19 : 0x%016lx 0x%016lx 0x%016lx 0x%016lx\n"
+           "GPR 20-23 : 0x%016lx 0x%016lx 0x%016lx 0x%016lx\n"
+           "GPR 24-27 : 0x%016lx 0x%016lx 0x%016lx 0x%016lx\n"
+           "GPR 28-31 : 0x%016lx 0x%016lx 0x%016lx 0x%016lx\n\n",
+           exception_name_from_vec(regs->entry_vector), regs->entry_vector,
+           regs->gprs[0], regs->gprs[1], regs->gprs[2], regs->gprs[3],
+           regs->gprs[4], regs->gprs[5], regs->gprs[6], regs->gprs[7],
+           regs->gprs[8], regs->gprs[9], regs->gprs[10], regs->gprs[11],
+           regs->gprs[12], regs->gprs[13], regs->gprs[14], regs->gprs[15],
+           regs->gprs[16], regs->gprs[17], regs->gprs[18], regs->gprs[19],
+           regs->gprs[20], regs->gprs[21], regs->gprs[22], regs->gprs[23],
+           regs->gprs[24], regs->gprs[25], regs->gprs[26], regs->gprs[27],
+           regs->gprs[28], regs->gprs[29], regs->gprs[30], regs->gprs[31]);
+    printk("LR        : 0x%016lx\n"
+           "CTR       : 0x%016lx\n"
+           "CR        : 0x%08x\n"
+           "PC        : 0x%016lx\n"
+           "MSR       : 0x%016lx\n"
+           "SRR0      : 0x%016lx\n"
+           "SRR1      : 0x%016lx\n"
+           "DAR       : 0x%016lx\n"
+           "DSISR     : 0x%08x\n",
+           regs->lr, regs->ctr, regs->cr, regs->pc, regs->msr, regs->srr0,
+           regs->srr1, regs->dar, regs->dsisr);
+
+    die();
+}
diff --git a/xen/arch/ppc/setup.c b/xen/arch/ppc/setup.c
index 959c1454a0..101bdd8bb6 100644
--- a/xen/arch/ppc/setup.c
+++ b/xen/arch/ppc/setup.c
@@ -11,6 +11,15 @@ 
 /* Xen stack for bringing up the first CPU. */
 unsigned char __initdata cpu0_boot_stack[STACK_SIZE] __aligned(STACK_SIZE);

+void setup_exceptions(void)
+{
+    unsigned long lpcr;
+
+    /* Set appropriate interrupt location in LPCR */
+    lpcr = mfspr(SPRN_LPCR);
+    mtspr(SPRN_LPCR, lpcr | LPCR_AIL_3);
+}
+
 void __init noreturn start_xen(unsigned long r3, unsigned long r4,
                                unsigned long r5, unsigned long r6,
                                unsigned long r7)
@@ -26,6 +35,8 @@  void __init noreturn start_xen(unsigned long r3, unsigned long r4,
         boot_opal_init((void *)r3);
     }

+    setup_exceptions();
+
     setup_initial_pagetables();

     early_printk("Hello, ppc64le!\n");