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authorDavid Howells <dhowells@redhat.com>2006-10-05 09:55:46 -0400
committerDavid Howells <dhowells@warthog.cambridge.redhat.com>2006-10-05 10:10:12 -0400
commit7d12e780e003f93433d49ce78cfedf4b4c52adc5 (patch)
tree6748550400445c11a306b132009f3001e3525df8 /arch/frv/kernel
parentda482792a6d1a3fbaaa25fae867b343fb4db3246 (diff)
IRQ: Maintain regs pointer globally rather than passing to IRQ handlers
Maintain a per-CPU global "struct pt_regs *" variable which can be used instead of passing regs around manually through all ~1800 interrupt handlers in the Linux kernel. The regs pointer is used in few places, but it potentially costs both stack space and code to pass it around. On the FRV arch, removing the regs parameter from all the genirq function results in a 20% speed up of the IRQ exit path (ie: from leaving timer_interrupt() to leaving do_IRQ()). Where appropriate, an arch may override the generic storage facility and do something different with the variable. On FRV, for instance, the address is maintained in GR28 at all times inside the kernel as part of general exception handling. Having looked over the code, it appears that the parameter may be handed down through up to twenty or so layers of functions. Consider a USB character device attached to a USB hub, attached to a USB controller that posts its interrupts through a cascaded auxiliary interrupt controller. A character device driver may want to pass regs to the sysrq handler through the input layer which adds another few layers of parameter passing. I've build this code with allyesconfig for x86_64 and i386. I've runtested the main part of the code on FRV and i386, though I can't test most of the drivers. I've also done partial conversion for powerpc and MIPS - these at least compile with minimal configurations. This will affect all archs. Mostly the changes should be relatively easy. Take do_IRQ(), store the regs pointer at the beginning, saving the old one: struct pt_regs *old_regs = set_irq_regs(regs); And put the old one back at the end: set_irq_regs(old_regs); Don't pass regs through to generic_handle_irq() or __do_IRQ(). In timer_interrupt(), this sort of change will be necessary: - update_process_times(user_mode(regs)); - profile_tick(CPU_PROFILING, regs); + update_process_times(user_mode(get_irq_regs())); + profile_tick(CPU_PROFILING); I'd like to move update_process_times()'s use of get_irq_regs() into itself, except that i386, alone of the archs, uses something other than user_mode(). Some notes on the interrupt handling in the drivers: (*) input_dev() is now gone entirely. The regs pointer is no longer stored in the input_dev struct. (*) finish_unlinks() in drivers/usb/host/ohci-q.c needs checking. It does something different depending on whether it's been supplied with a regs pointer or not. (*) Various IRQ handler function pointers have been moved to type irq_handler_t. Signed-Off-By: David Howells <dhowells@redhat.com> (cherry picked from 1b16e7ac850969f38b375e511e3fa2f474a33867 commit)
Diffstat (limited to 'arch/frv/kernel')
-rw-r--r--arch/frv/kernel/dma.c5
-rw-r--r--arch/frv/kernel/irq-mb93091.c4
-rw-r--r--arch/frv/kernel/irq-mb93093.c4
-rw-r--r--arch/frv/kernel/irq-mb93493.c4
-rw-r--r--arch/frv/kernel/irq.c2
-rw-r--r--arch/frv/kernel/time.c8
6 files changed, 13 insertions, 14 deletions
diff --git a/arch/frv/kernel/dma.c b/arch/frv/kernel/dma.c
index f5de6cf7df4e..156184e17e57 100644
--- a/arch/frv/kernel/dma.c
+++ b/arch/frv/kernel/dma.c
@@ -121,15 +121,14 @@ unsigned long frv_dma_inprogress;
121/* 121/*
122 * DMA irq handler - determine channel involved, grab status and call real handler 122 * DMA irq handler - determine channel involved, grab status and call real handler
123 */ 123 */
124static irqreturn_t dma_irq_handler(int irq, void *_channel, struct pt_regs *regs) 124static irqreturn_t dma_irq_handler(int irq, void *_channel)
125{ 125{
126 struct frv_dma_channel *channel = _channel; 126 struct frv_dma_channel *channel = _channel;
127 127
128 frv_clear_dma_inprogress(channel - frv_dma_channels); 128 frv_clear_dma_inprogress(channel - frv_dma_channels);
129 return channel->handler(channel - frv_dma_channels, 129 return channel->handler(channel - frv_dma_channels,
130 __get_DMAC(channel->ioaddr, CSTR), 130 __get_DMAC(channel->ioaddr, CSTR),
131 channel->data, 131 channel->data);
132 regs);
133 132
134} /* end dma_irq_handler() */ 133} /* end dma_irq_handler() */
135 134
diff --git a/arch/frv/kernel/irq-mb93091.c b/arch/frv/kernel/irq-mb93091.c
index 369bc0a7443d..ad753c1e9b8f 100644
--- a/arch/frv/kernel/irq-mb93091.c
+++ b/arch/frv/kernel/irq-mb93091.c
@@ -80,7 +80,7 @@ static struct irq_chip frv_fpga_pic = {
80/* 80/*
81 * FPGA PIC interrupt handler 81 * FPGA PIC interrupt handler
82 */ 82 */
83static irqreturn_t fpga_interrupt(int irq, void *_mask, struct pt_regs *regs) 83static irqreturn_t fpga_interrupt(int irq, void *_mask)
84{ 84{
85 uint16_t imr, mask = (unsigned long) _mask; 85 uint16_t imr, mask = (unsigned long) _mask;
86 86
@@ -95,7 +95,7 @@ static irqreturn_t fpga_interrupt(int irq, void *_mask, struct pt_regs *regs)
95 irq = 31 - irq; 95 irq = 31 - irq;
96 mask &= ~(1 << irq); 96 mask &= ~(1 << irq);
97 97
98 generic_handle_irq(IRQ_BASE_FPGA + irq, regs); 98 generic_handle_irq(IRQ_BASE_FPGA + irq);
99 } 99 }
100 100
101 return IRQ_HANDLED; 101 return IRQ_HANDLED;
diff --git a/arch/frv/kernel/irq-mb93093.c b/arch/frv/kernel/irq-mb93093.c
index a43a22158956..e0983f6926ed 100644
--- a/arch/frv/kernel/irq-mb93093.c
+++ b/arch/frv/kernel/irq-mb93093.c
@@ -79,7 +79,7 @@ static struct irq_chip frv_fpga_pic = {
79/* 79/*
80 * FPGA PIC interrupt handler 80 * FPGA PIC interrupt handler
81 */ 81 */
82static irqreturn_t fpga_interrupt(int irq, void *_mask, struct pt_regs *regs) 82static irqreturn_t fpga_interrupt(int irq, void *_mask)
83{ 83{
84 uint16_t imr, mask = (unsigned long) _mask; 84 uint16_t imr, mask = (unsigned long) _mask;
85 85
@@ -94,7 +94,7 @@ static irqreturn_t fpga_interrupt(int irq, void *_mask, struct pt_regs *regs)
94 irq = 31 - irq; 94 irq = 31 - irq;
95 mask &= ~(1 << irq); 95 mask &= ~(1 << irq);
96 96
97 generic_irq_handle(IRQ_BASE_FPGA + irq, regs); 97 generic_irq_handle(IRQ_BASE_FPGA + irq);
98 } 98 }
99 99
100 return IRQ_HANDLED; 100 return IRQ_HANDLED;
diff --git a/arch/frv/kernel/irq-mb93493.c b/arch/frv/kernel/irq-mb93493.c
index 39c0188a3498..c157eeff871d 100644
--- a/arch/frv/kernel/irq-mb93493.c
+++ b/arch/frv/kernel/irq-mb93493.c
@@ -90,7 +90,7 @@ static struct irq_chip frv_mb93493_pic = {
90/* 90/*
91 * MB93493 PIC interrupt handler 91 * MB93493 PIC interrupt handler
92 */ 92 */
93static irqreturn_t mb93493_interrupt(int irq, void *_piqsr, struct pt_regs *regs) 93static irqreturn_t mb93493_interrupt(int irq, void *_piqsr)
94{ 94{
95 volatile void *piqsr = _piqsr; 95 volatile void *piqsr = _piqsr;
96 uint32_t iqsr; 96 uint32_t iqsr;
@@ -106,7 +106,7 @@ static irqreturn_t mb93493_interrupt(int irq, void *_piqsr, struct pt_regs *regs
106 irq = 31 - irq; 106 irq = 31 - irq;
107 iqsr &= ~(1 << irq); 107 iqsr &= ~(1 << irq);
108 108
109 generic_handle_irq(IRQ_BASE_MB93493 + irq, regs); 109 generic_handle_irq(IRQ_BASE_MB93493 + irq);
110 } 110 }
111 111
112 return IRQ_HANDLED; 112 return IRQ_HANDLED;
diff --git a/arch/frv/kernel/irq.c b/arch/frv/kernel/irq.c
index 5ac041c7c0a4..87f360a4ea27 100644
--- a/arch/frv/kernel/irq.c
+++ b/arch/frv/kernel/irq.c
@@ -143,7 +143,7 @@ static struct irq_chip frv_cpu_pic = {
143asmlinkage void do_IRQ(void) 143asmlinkage void do_IRQ(void)
144{ 144{
145 irq_enter(); 145 irq_enter();
146 generic_handle_irq(__get_IRL(), __frame); 146 generic_handle_irq(__get_IRL());
147 irq_exit(); 147 irq_exit();
148} 148}
149 149
diff --git a/arch/frv/kernel/time.c b/arch/frv/kernel/time.c
index 44a9aebc4f5a..ed588d73d7d8 100644
--- a/arch/frv/kernel/time.c
+++ b/arch/frv/kernel/time.c
@@ -40,7 +40,7 @@ unsigned long __nongprelbss __dsu_clock_speed_HZ;
40unsigned long __nongprelbss __serial_clock_speed_HZ; 40unsigned long __nongprelbss __serial_clock_speed_HZ;
41unsigned long __delay_loops_MHz; 41unsigned long __delay_loops_MHz;
42 42
43static irqreturn_t timer_interrupt(int irq, void *dummy, struct pt_regs *regs); 43static irqreturn_t timer_interrupt(int irq, void *dummy);
44 44
45static struct irqaction timer_irq = { 45static struct irqaction timer_irq = {
46 timer_interrupt, IRQF_DISABLED, CPU_MASK_NONE, "timer", NULL, NULL 46 timer_interrupt, IRQF_DISABLED, CPU_MASK_NONE, "timer", NULL, NULL
@@ -55,7 +55,7 @@ static inline int set_rtc_mmss(unsigned long nowtime)
55 * timer_interrupt() needs to keep up the real-time clock, 55 * timer_interrupt() needs to keep up the real-time clock,
56 * as well as call the "do_timer()" routine every clocktick 56 * as well as call the "do_timer()" routine every clocktick
57 */ 57 */
58static irqreturn_t timer_interrupt(int irq, void *dummy, struct pt_regs * regs) 58static irqreturn_t timer_interrupt(int irq, void *dummy)
59{ 59{
60 /* last time the cmos clock got updated */ 60 /* last time the cmos clock got updated */
61 static long last_rtc_update = 0; 61 static long last_rtc_update = 0;
@@ -70,8 +70,8 @@ static irqreturn_t timer_interrupt(int irq, void *dummy, struct pt_regs * regs)
70 write_seqlock(&xtime_lock); 70 write_seqlock(&xtime_lock);
71 71
72 do_timer(1); 72 do_timer(1);
73 update_process_times(user_mode(regs)); 73 update_process_times(user_mode(get_irq_regs()));
74 profile_tick(CPU_PROFILING, regs); 74 profile_tick(CPU_PROFILING);
75 75
76 /* 76 /*
77 * If we have an externally synchronized Linux clock, then update 77 * If we have an externally synchronized Linux clock, then update