From f5316b4aea024da9266d740322a5481657f6ce59 Mon Sep 17 00:00:00 2001 From: Jason Wessel Date: Thu, 20 May 2010 21:04:22 -0500 Subject: [PATCH] kgdb,8250,pl011: Return immediately from console poll The design of the kdb shell requires that every device that can provide input to kdb have a polling routine that exits immediately if there is no character available. This is required in order to get the page scrolling mechanism working. Changing the kernel debugger I/O API to require all polling character routines to exit immediately if there is no data allows the kernel debugger to process multiple input channels. NO_POLL_CHAR will be the return code to the polling routine when ever there is no character available. CC: linux-serial@vger.kernel.org Signed-off-by: Jason Wessel --- drivers/serial/8250.c | 4 ++-- drivers/serial/amba-pl011.c | 6 +++--- include/linux/kdb.h | 1 + include/linux/serial_core.h | 1 + kernel/debug/debug_core.c | 2 ++ kernel/debug/gdbstub.c | 37 +++++++++++++++++++++++++++------ kernel/debug/kdb/kdb_debugger.c | 10 +++++++++ 7 files changed, 50 insertions(+), 11 deletions(-) diff --git a/drivers/serial/8250.c b/drivers/serial/8250.c index 2b1ea3d4c4f4..891e1dd65f24 100644 --- a/drivers/serial/8250.c +++ b/drivers/serial/8250.c @@ -1891,8 +1891,8 @@ static int serial8250_get_poll_char(struct uart_port *port) struct uart_8250_port *up = (struct uart_8250_port *)port; unsigned char lsr = serial_inp(up, UART_LSR); - while (!(lsr & UART_LSR_DR)) - lsr = serial_inp(up, UART_LSR); + if (!(lsr & UART_LSR_DR)) + return NO_POLL_CHAR; return serial_inp(up, UART_RX); } diff --git a/drivers/serial/amba-pl011.c b/drivers/serial/amba-pl011.c index 743ebf5f16da..eb4cb480b93e 100644 --- a/drivers/serial/amba-pl011.c +++ b/drivers/serial/amba-pl011.c @@ -342,9 +342,9 @@ static int pl010_get_poll_char(struct uart_port *port) struct uart_amba_port *uap = (struct uart_amba_port *)port; unsigned int status; - do { - status = readw(uap->port.membase + UART01x_FR); - } while (status & UART01x_FR_RXFE); + status = readw(uap->port.membase + UART01x_FR); + if (status & UART01x_FR_RXFE) + return NO_POLL_CHAR; return readw(uap->port.membase + UART01x_DR); } diff --git a/include/linux/kdb.h b/include/linux/kdb.h index 4d93790faec3..d72fa3908128 100644 --- a/include/linux/kdb.h +++ b/include/linux/kdb.h @@ -19,6 +19,7 @@ #include #define KDB_POLL_FUNC_MAX 5 +extern int kdb_poll_idx; /* * kdb_initial_cpu is initialized to -1, and is set to the cpu diff --git a/include/linux/serial_core.h b/include/linux/serial_core.h index 78dd1e7120a9..ad839963fa68 100644 --- a/include/linux/serial_core.h +++ b/include/linux/serial_core.h @@ -246,6 +246,7 @@ struct uart_ops { #endif }; +#define NO_POLL_CHAR 0x00ff0000 #define UART_CONFIG_TYPE (1 << 0) #define UART_CONFIG_IRQ (1 << 1) diff --git a/kernel/debug/debug_core.c b/kernel/debug/debug_core.c index 6e1fa829fdeb..1d71df66f3fa 100644 --- a/kernel/debug/debug_core.c +++ b/kernel/debug/debug_core.c @@ -882,6 +882,8 @@ EXPORT_SYMBOL_GPL(kgdb_unregister_io_module); int dbg_io_get_char(void) { int ret = dbg_io_ops->read_char(); + if (ret == NO_POLL_CHAR) + return -1; if (!dbg_kdb_mode) return ret; if (ret == 127) diff --git a/kernel/debug/gdbstub.c b/kernel/debug/gdbstub.c index 188203a19657..3c000490a7dd 100644 --- a/kernel/debug/gdbstub.c +++ b/kernel/debug/gdbstub.c @@ -30,6 +30,7 @@ #include #include +#include #include #include #include @@ -62,6 +63,30 @@ static int hex(char ch) return -1; } +#ifdef CONFIG_KGDB_KDB +static int gdbstub_read_wait(void) +{ + int ret = -1; + int i; + + /* poll any additional I/O interfaces that are defined */ + while (ret < 0) + for (i = 0; kdb_poll_funcs[i] != NULL; i++) { + ret = kdb_poll_funcs[i](); + if (ret > 0) + break; + } + return ret; +} +#else +static int gdbstub_read_wait(void) +{ + int ret = dbg_io_ops->read_char(); + while (ret == NO_POLL_CHAR) + ret = dbg_io_ops->read_char(); + return ret; +} +#endif /* scan for the sequence $# */ static void get_packet(char *buffer) { @@ -75,7 +100,7 @@ static void get_packet(char *buffer) * Spin and wait around for the start character, ignore all * other characters: */ - while ((ch = (dbg_io_ops->read_char())) != '$') + while ((ch = (gdbstub_read_wait())) != '$') /* nothing */; kgdb_connected = 1; @@ -88,7 +113,7 @@ static void get_packet(char *buffer) * now, read until a # or end of buffer is found: */ while (count < (BUFMAX - 1)) { - ch = dbg_io_ops->read_char(); + ch = gdbstub_read_wait(); if (ch == '#') break; checksum = checksum + ch; @@ -98,8 +123,8 @@ static void get_packet(char *buffer) buffer[count] = 0; if (ch == '#') { - xmitcsum = hex(dbg_io_ops->read_char()) << 4; - xmitcsum += hex(dbg_io_ops->read_char()); + xmitcsum = hex(gdbstub_read_wait()) << 4; + xmitcsum += hex(gdbstub_read_wait()); if (checksum != xmitcsum) /* failed checksum */ @@ -144,10 +169,10 @@ static void put_packet(char *buffer) dbg_io_ops->flush(); /* Now see what we get in reply. */ - ch = dbg_io_ops->read_char(); + ch = gdbstub_read_wait(); if (ch == 3) - ch = dbg_io_ops->read_char(); + ch = gdbstub_read_wait(); /* If we get an ACK, we are done. */ if (ch == '+') diff --git a/kernel/debug/kdb/kdb_debugger.c b/kernel/debug/kdb/kdb_debugger.c index f024c0c4b8c4..bf6e8270e957 100644 --- a/kernel/debug/kdb/kdb_debugger.c +++ b/kernel/debug/kdb/kdb_debugger.c @@ -20,7 +20,15 @@ get_char_func kdb_poll_funcs[] = { dbg_io_get_char, NULL, + NULL, + NULL, + NULL, + NULL, }; +EXPORT_SYMBOL_GPL(kdb_poll_funcs); + +int kdb_poll_idx = 1; +EXPORT_SYMBOL_GPL(kdb_poll_idx); int kdb_stub(struct kgdb_state *ks) { @@ -85,6 +93,7 @@ int kdb_stub(struct kgdb_state *ks) kdb_bp_remove(); KDB_STATE_CLEAR(DOING_SS); KDB_STATE_CLEAR(DOING_SSB); + KDB_STATE_SET(PAGER); /* zero out any offline cpu data */ for_each_present_cpu(i) { if (!cpu_online(i)) { @@ -112,6 +121,7 @@ int kdb_stub(struct kgdb_state *ks) kdb_initial_cpu = -1; kdb_current_task = NULL; kdb_current_regs = NULL; + KDB_STATE_CLEAR(PAGER); kdbnearsym_cleanup(); if (error == KDB_CMD_KGDB) { if (KDB_STATE(DOING_KGDB) || KDB_STATE(DOING_KGDB2)) { -- 2.20.1