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Sun, 15 May 2022 12:03:47 -0400 (EDT) Subject: Re: [PATCH 02/13] openrisc: Cleanup emergency print handling To: Stafford Horne References: <20220515124158.3167452-1-shorne@gmail.com> <20220515124158.3167452-3-shorne@gmail.com> From: Samuel Holland Message-ID: <7b18962e-d1ce-699f-dd59-719255f19ade@sholland.org> Date: Sun, 15 May 2022 11:03:47 -0500 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.6.0 MIME-Version: 1.0 In-Reply-To: <20220515124158.3167452-3-shorne@gmail.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-BeenThere: openrisc@lists.librecores.org X-Mailman-Version: 2.1.26 Precedence: list List-Id: Discussion around the OpenRISC processor List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Jonas Bonn , Openrisc , Randy Dunlap , LKML Errors-To: openrisc-bounces@lists.librecores.org Sender: "OpenRISC" Hi Stafford, On 5/15/22 7:41 AM, Stafford Horne wrote: > 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 > --- > arch/openrisc/kernel/head.S | 148 +++++++++++++++++++++--------------- > 1 file changed, 85 insertions(+), 63 deletions(-) > > diff --git a/arch/openrisc/kernel/head.S b/arch/openrisc/kernel/head.S > index 15f1b38dfe03..b1f3a65c271c 100644 > --- a/arch/openrisc/kernel/head.S > +++ b/arch/openrisc/kernel/head.S > @@ -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 ;\ > @@ -1530,65 +1534,99 @@ trampoline_out: > l.jr r9 > l.nop > > - > /* > - * DSCR: prints a string referenced by r3. > + * DESC: Prints ASCII character stored in r7 > * > - * PRMS: r3 - address of the first character of null > - * terminated string to be printed > + * PRMS: r7 - a 32-bit value with an ASCII character in the first byte > + * position. > * > - * PREQ: UART at UART_BASE_ADD has to be initialized > + * PREQ: The UART at UART_BASE_ADD has to be initialized > * > - * POST: caller should be aware that r3, r9 are changed > + * 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_print) > +ENTRY(_emergency_putc) > 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 > - l.bf 9f > - l.nop > > -// putc: > l.movhi r4,hi(UART_BASE_ADD) > + l.ori r4,r4,lo(UART_BASE_ADD) > > +#elif defined(CONFIG_SERIAL_8250) This needs to use #if in this patch (and #elif in the next patch). Regards, Samuel > + /* 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 > + 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 > + 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. > + * > + * PRMS: r3 - address of the first character of null > + * terminated string to be printed > + * > + * PREQ: UART at UART_BASE_ADD has to be initialized > + * > + * POST: caller should be aware that r3, r9 are changed > + */ > +ENTRY(_emergency_print) > + EMERGENCY_PRINT_STORE_GPR7 > + 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.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 ]=== */ >