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openrisc: Cleanup emergency print handling

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The emergency print support only works for 8250 compatible serial ports.
Now that OpenRISC platforms may be configured with different serial port
hardware we don't want emergency print to try to print to non-existent
hardware which will cause lockups.

This patch contains several fixes to get emergency print working again:

 - Update symbol loading to not assume the location of symbols
 - Split the putc print operation out to its own function to allow
   for different future implementations.
 - Update _emergency_print_nr and _emergency_print to use the putc
   function.
 - Guard serial 8250 specific sequences by CONFIG_SERIAL_8250
 - Update string line feed from lf,cr to cr,lf.

Signed-off-by: Stafford Horne <shorne@gmail.com>
This commit is contained in:
Stafford Horne 2022-05-15 13:21:31 +09:00
parent 87e387acd8
commit e449759c24
1 changed files with 94 additions and 72 deletions
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166
arch/openrisc/kernel/head.S
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@ -297,19 +297,23 @@
/* temporary store r3, r9 into r1, r10 */ ;\
l.addi r1,r3,0x0 ;\
l.addi r10,r9,0x0 ;\
/* the string referenced by r3 must be low enough */ ;\
LOAD_SYMBOL_2_GPR(r9,_string_unhandled_exception) ;\
tophys (r3,r9) ;\
l.jal _emergency_print ;\
l.ori r3,r0,lo(_string_unhandled_exception) ;\
l.nop ;\
l.mfspr r3,r0,SPR_NPC ;\
l.jal _emergency_print_nr ;\
l.andi r3,r3,0x1f00 ;\
/* the string referenced by r3 must be low enough */ ;\
l.andi r3,r3,0x1f00 ;\
LOAD_SYMBOL_2_GPR(r9,_string_epc_prefix) ;\
tophys (r3,r9) ;\
l.jal _emergency_print ;\
l.ori r3,r0,lo(_string_epc_prefix) ;\
l.nop ;\
l.jal _emergency_print_nr ;\
l.mfspr r3,r0,SPR_EPCR_BASE ;\
l.mfspr r3,r0,SPR_EPCR_BASE ;\
LOAD_SYMBOL_2_GPR(r9,_string_nl) ;\
tophys (r3,r9) ;\
l.jal _emergency_print ;\
l.ori r3,r0,lo(_string_nl) ;\
l.nop ;\
/* end of printing */ ;\
l.addi r3,r1,0x0 ;\
l.addi r9,r10,0x0 ;\
@ -1530,6 +1534,52 @@ trampoline_out:
l.jr r9
l.nop
/*
* DESC: Prints ASCII character stored in r7
*
* PRMS: r7 - a 32-bit value with an ASCII character in the first byte
* position.
*
* PREQ: The UART at UART_BASE_ADD has to be initialized
*
* POST: internally used but restores:
* r4 - to store UART_BASE_ADD
* r5 - for loading OFF_TXFULL / THRE,TEMT
* r6 - for storing bitmask (SERIAL_8250)
*/
ENTRY(_emergency_putc)
EMERGENCY_PRINT_STORE_GPR4
EMERGENCY_PRINT_STORE_GPR5
EMERGENCY_PRINT_STORE_GPR6
l.movhi r4,hi(UART_BASE_ADD)
l.ori r4,r4,lo(UART_BASE_ADD)
#if defined(CONFIG_SERIAL_8250)
/* Check UART LSR THRE (hold) bit */
l.addi r6,r0,0x20
1: l.lbz r5,5(r4)
l.andi r5,r5,0x20
l.sfeq r5,r6
l.bnf 1b
l.nop
/* Write character */
l.sb 0(r4),r7
/* Check UART LSR THRE|TEMT (hold, empty) bits */
l.addi r6,r0,0x60
1: l.lbz r5,5(r4)
l.andi r5,r5,0x60
l.sfeq r5,r6
l.bnf 1b
l.nop
#endif
EMERGENCY_PRINT_LOAD_GPR6
EMERGENCY_PRINT_LOAD_GPR5
EMERGENCY_PRINT_LOAD_GPR4
l.jr r9
l.nop
/*
* DSCR: prints a string referenced by r3.
@ -1542,53 +1592,41 @@ trampoline_out:
* POST: caller should be aware that r3, r9 are changed
*/
ENTRY(_emergency_print)
EMERGENCY_PRINT_STORE_GPR4
EMERGENCY_PRINT_STORE_GPR5
EMERGENCY_PRINT_STORE_GPR6
EMERGENCY_PRINT_STORE_GPR7
2:
l.lbz r7,0(r3)
l.sfeq r7,r0
EMERGENCY_PRINT_STORE_GPR9
/* Load character to r7, check for null terminator */
2: l.lbz r7,0(r3)
l.sfeqi r7,0x0
l.bf 9f
l.nop
l.nop
// putc:
l.movhi r4,hi(UART_BASE_ADD)
l.addi r6,r0,0x20
1: l.lbz r5,5(r4)
l.andi r5,r5,0x20
l.sfeq r5,r6
l.bnf 1b
l.nop
l.sb 0(r4),r7
l.addi r6,r0,0x60
1: l.lbz r5,5(r4)
l.andi r5,r5,0x60
l.sfeq r5,r6
l.bnf 1b
l.nop
l.jal _emergency_putc
l.nop
/* next character */
l.j 2b
l.addi r3,r3,0x1
l.addi r3,r3,0x1
9:
EMERGENCY_PRINT_LOAD_GPR9
EMERGENCY_PRINT_LOAD_GPR7
EMERGENCY_PRINT_LOAD_GPR6
EMERGENCY_PRINT_LOAD_GPR5
EMERGENCY_PRINT_LOAD_GPR4
l.jr r9
l.nop
l.nop
/*
* DSCR: prints a number in r3 in hex.
*
* PRMS: r3 - a 32-bit unsigned integer
*
* PREQ: UART at UART_BASE_ADD has to be initialized
*
* POST: caller should be aware that r3, r9 are changed
*/
ENTRY(_emergency_print_nr)
EMERGENCY_PRINT_STORE_GPR4
EMERGENCY_PRINT_STORE_GPR5
EMERGENCY_PRINT_STORE_GPR6
EMERGENCY_PRINT_STORE_GPR7
EMERGENCY_PRINT_STORE_GPR8
EMERGENCY_PRINT_STORE_GPR9
l.addi r8,r0,32 // shift register
@ -1600,58 +1638,39 @@ ENTRY(_emergency_print_nr)
/* don't skip the last zero if number == 0x0 */
l.sfeqi r8,0x4
l.bf 2f
l.nop
l.nop
l.sfeq r7,r0
l.bf 1b
l.nop
l.nop
2:
l.srl r7,r3,r8
l.andi r7,r7,0xf
l.sflts r8,r0
l.bf 9f
l.bf 9f
/* Numbers greater than 9 translate to a-f */
l.sfgtui r7,0x9
l.bnf 8f
l.nop
l.nop
l.addi r7,r7,0x27
8:
l.addi r7,r7,0x30
// putc:
l.movhi r4,hi(UART_BASE_ADD)
l.addi r6,r0,0x20
1: l.lbz r5,5(r4)
l.andi r5,r5,0x20
l.sfeq r5,r6
l.bnf 1b
l.nop
l.sb 0(r4),r7
l.addi r6,r0,0x60
1: l.lbz r5,5(r4)
l.andi r5,r5,0x60
l.sfeq r5,r6
l.bnf 1b
l.nop
/* Convert to ascii and output character */
8: l.jal _emergency_putc
l.addi r7,r7,0x30
/* next character */
l.j 2b
l.addi r8,r8,-0x4
9:
EMERGENCY_PRINT_LOAD_GPR9
EMERGENCY_PRINT_LOAD_GPR8
EMERGENCY_PRINT_LOAD_GPR7
EMERGENCY_PRINT_LOAD_GPR6
EMERGENCY_PRINT_LOAD_GPR5
EMERGENCY_PRINT_LOAD_GPR4
l.jr r9
l.nop
l.nop
/*
* This should be used for debugging only.
@ -1676,7 +1695,9 @@ ENTRY(_emergency_print_nr)
ENTRY(_early_uart_init)
l.movhi r3,hi(UART_BASE_ADD)
l.ori r3,r3,lo(UART_BASE_ADD)
#if defined(CONFIG_SERIAL_8250)
l.addi r4,r0,0x7
l.sb 0x2(r3),r4
@ -1694,9 +1715,10 @@ ENTRY(_early_uart_init)
l.addi r4,r0,((UART_DIVISOR) & 0x000000ff)
l.sb UART_DLL(r3),r4
l.sb 0x3(r3),r5
#endif
l.jr r9
l.nop
l.nop
.align 0x1000
.global _secondary_evbar
@ -1711,13 +1733,13 @@ _secondary_evbar:
.section .rodata
_string_unhandled_exception:
.string "\n\rRunarunaround: Unhandled exception 0x\0"
.string "\r\nRunarunaround: Unhandled exception 0x\0"
_string_epc_prefix:
.string ": EPC=0x\0"
_string_nl:
.string "\n\r\0"
.string "\r\n\0"
/* ========================================[ page aligned structures ]=== */