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Debug: enable kernel boot up time measurement #9

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Merged
michael2012z merged 1 commit into from
Mar 9, 2022
Merged

Debug: enable kernel boot up time measurement #9

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16 changes: 16 additions & 0 deletions arch/arm64/kernel/head.S
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Original file line number Diff line number Diff line change
Expand Up @@ -89,6 +89,7 @@
* x24 __primary_switch() .. relocate_kernel() current RELR displacement
*/
SYM_CODE_START(primary_entry)
bl trap_to_vmm
bl preserve_boot_args
bl init_kernel_el // w0=cpu_boot_mode
adrp x23, __PHYS_OFFSET
Expand All @@ -105,6 +106,21 @@ SYM_CODE_START(primary_entry)
b __primary_switch
SYM_CODE_END(primary_entry)

/*
* By writing to mmio region, trap to vmm to print timestamp,
* but corrupt x7 and x8.
* 0x9000f00 is debug region of pl011
* 0x40 is the code specified in cloud hypervisor indicating the first debug
* point of kernel.
*/
SYM_CODE_START(trap_to_vmm)
movz x7, 0x0900, lsl 16
add x7, x7, 0xf00
mov x8, 0x40
str w8, [x7]
ret
SYM_CODE_END(trap_to_vmm)

/*
* Preserve the arguments passed by the bootloader in x0 .. x3
*/
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5 changes: 5 additions & 0 deletions drivers/tty/serial/amba-pl011.c
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Original file line number Diff line number Diff line change
Expand Up @@ -44,6 +44,8 @@

#include "amba-pl011.h"

char __iomem *pl011_debug_addr;

#define UART_NR 14

#define SERIAL_AMBA_MAJOR 204
Expand Down Expand Up @@ -2752,6 +2754,9 @@ static int pl011_setup_port(struct device *dev, struct uart_amba_port *uap,
if (IS_ERR(base))
return PTR_ERR(base);

pl011_debug_addr = (char __iomem *)base;
pl011_debug_addr += UART011_IO_DEBUG;

index = pl011_probe_dt_alias(index, dev);

uap->old_cr = 0;
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11 changes: 11 additions & 0 deletions include/linux/amba/serial.h
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Original file line number Diff line number Diff line change
Expand Up @@ -206,6 +206,8 @@
#define UART01x_RSR_ANY (UART01x_RSR_OE|UART01x_RSR_BE|UART01x_RSR_PE|UART01x_RSR_FE)
#define UART01x_FR_MODEM_ANY (UART01x_FR_DCD|UART01x_FR_DSR|UART01x_FR_CTS)

#define UART011_IO_DEBUG 0xf00 /* used for debug I/O port emulation in VM */

#ifndef __ASSEMBLY__
struct amba_device; /* in uncompress this is included but amba/bus.h is not */
struct amba_pl010_data {
Expand All @@ -225,4 +227,13 @@ struct amba_pl011_data {
};
#endif

extern char __iomem *pl011_debug_addr; /* save the pl011 debug mmio address, equal to base + UART011_IO_DEBUG */
#define DEBUG_TRAP_VAL_END_BOOT 0x41 /* debug point at the end of kernel boot */

/* wrapper of tricking pl011 debug */
static inline void pl011_debug_trap(char val)
{
writeb_relaxed(val, pl011_debug_addr);
}

#endif
5 changes: 5 additions & 0 deletions init/main.c
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Original file line number Diff line number Diff line change
Expand Up @@ -100,6 +100,7 @@
#include <linux/kcsan.h>
#include <linux/init_syscalls.h>
#include <linux/stackdepot.h>
#include <linux/amba/serial.h>

#include <asm/io.h>
#include <asm/bugs.h>
Expand Down Expand Up @@ -1536,6 +1537,10 @@ static int __ref kernel_init(void *unused)
outb(0x41, 0x80);
#endif

#ifdef CONFIG_ARM64
pl011_debug_trap(DEBUG_TRAP_VAL_END_BOOT);
#endif

if (ramdisk_execute_command) {
ret = run_init_process(ramdisk_execute_command);
if (!ret)
Expand Down