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Sun, 15 May 2022 14:36:10 -0700 (PDT) Received: from localhost ([2409:10:24a0:4700:e8ad:216a:2a9d:6d0c]) by smtp.gmail.com with ESMTPSA id d2-20020a170902cec200b0015e8d4eb2ddsm5530452plg.295.2022.05.15.14.36.09 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 15 May 2022 14:36:10 -0700 (PDT) Date: Mon, 16 May 2022 06:36:08 +0900 From: Stafford Horne To: Samuel Holland Cc: LKML , Jonas Bonn , Openrisc , Randy Dunlap Subject: Re: [PATCH 02/13] openrisc: Cleanup emergency print handling Message-ID: References: <20220515124158.3167452-1-shorne@gmail.com> <20220515124158.3167452-3-shorne@gmail.com> <7b18962e-d1ce-699f-dd59-719255f19ade@sholland.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <7b18962e-d1ce-699f-dd59-719255f19ade@sholland.org> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, May 15, 2022 at 11:03:47AM -0500, Samuel Holland wrote: > 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). Thnak you. right, I split these patches up at the last moment and I messed up these ifdefs. They work together but not separated. I will fix this, do some testing and send a v2 tomorrow. Patches posted here: https://github.com/stffrdhrn/linux/commits/or1k-5.19-cleanups -Stafford > > + /* 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 ]=== */ > > >