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)
diff --git a/drivers/mmc/at91_mci.c b/drivers/mmc/at91_mci.c
index cb142a6..494b23f 100644
--- a/drivers/mmc/at91_mci.c
+++ b/drivers/mmc/at91_mci.c
@@ -661,7 +661,7 @@
/*
* Handle an interrupt
*/
-static irqreturn_t at91_mci_irq(int irq, void *devid, struct pt_regs *regs)
+static irqreturn_t at91_mci_irq(int irq, void *devid)
{
struct at91mci_host *host = devid;
int completed = 0;
@@ -754,7 +754,7 @@
return IRQ_HANDLED;
}
-static irqreturn_t at91_mmc_det_irq(int irq, void *_host, struct pt_regs *regs)
+static irqreturn_t at91_mmc_det_irq(int irq, void *_host)
{
struct at91mci_host *host = _host;
int present = !at91_get_gpio_value(irq);
diff --git a/drivers/mmc/au1xmmc.c b/drivers/mmc/au1xmmc.c
index 61268da..53ffcbb 100644
--- a/drivers/mmc/au1xmmc.c
+++ b/drivers/mmc/au1xmmc.c
@@ -750,7 +750,7 @@
#define STATUS_DATA_IN (SD_STATUS_NE)
#define STATUS_DATA_OUT (SD_STATUS_TH)
-static irqreturn_t au1xmmc_irq(int irq, void *dev_id, struct pt_regs *regs)
+static irqreturn_t au1xmmc_irq(int irq, void *dev_id)
{
u32 status;
diff --git a/drivers/mmc/imxmmc.c b/drivers/mmc/imxmmc.c
index 1b79dd2..659d4a8 100644
--- a/drivers/mmc/imxmmc.c
+++ b/drivers/mmc/imxmmc.c
@@ -635,7 +635,7 @@
return trans_done;
}
-static void imxmci_dma_irq(int dma, void *devid, struct pt_regs *regs)
+static void imxmci_dma_irq(int dma, void *devid)
{
struct imxmci_host *host = devid;
uint32_t stat = MMC_STATUS;
@@ -646,7 +646,7 @@
tasklet_schedule(&host->tasklet);
}
-static irqreturn_t imxmci_irq(int irq, void *devid, struct pt_regs *regs)
+static irqreturn_t imxmci_irq(int irq, void *devid)
{
struct imxmci_host *host = devid;
uint32_t stat = MMC_STATUS;
diff --git a/drivers/mmc/mmci.c b/drivers/mmc/mmci.c
index 2b5a0cc..828503c 100644
--- a/drivers/mmc/mmci.c
+++ b/drivers/mmc/mmci.c
@@ -261,7 +261,7 @@
/*
* PIO data transfer IRQ handler.
*/
-static irqreturn_t mmci_pio_irq(int irq, void *dev_id, struct pt_regs *regs)
+static irqreturn_t mmci_pio_irq(int irq, void *dev_id)
{
struct mmci_host *host = dev_id;
void __iomem *base = host->base;
@@ -347,7 +347,7 @@
/*
* Handle completion of command and data transfers.
*/
-static irqreturn_t mmci_irq(int irq, void *dev_id, struct pt_regs *regs)
+static irqreturn_t mmci_irq(int irq, void *dev_id)
{
struct mmci_host *host = dev_id;
u32 status;
diff --git a/drivers/mmc/omap.c b/drivers/mmc/omap.c
index 52c9e52..762fa28 100644
--- a/drivers/mmc/omap.c
+++ b/drivers/mmc/omap.c
@@ -377,7 +377,7 @@
}
}
-static irqreturn_t mmc_omap_irq(int irq, void *dev_id, struct pt_regs *regs)
+static irqreturn_t mmc_omap_irq(int irq, void *dev_id)
{
struct mmc_omap_host * host = (struct mmc_omap_host *)dev_id;
u16 status;
@@ -514,7 +514,7 @@
return IRQ_HANDLED;
}
-static irqreturn_t mmc_omap_switch_irq(int irq, void *dev_id, struct pt_regs *regs)
+static irqreturn_t mmc_omap_switch_irq(int irq, void *dev_id)
{
struct mmc_omap_host *host = (struct mmc_omap_host *) dev_id;
diff --git a/drivers/mmc/pxamci.c b/drivers/mmc/pxamci.c
index ef35090..a526698 100644
--- a/drivers/mmc/pxamci.c
+++ b/drivers/mmc/pxamci.c
@@ -299,7 +299,7 @@
return 1;
}
-static irqreturn_t pxamci_irq(int irq, void *devid, struct pt_regs *regs)
+static irqreturn_t pxamci_irq(int irq, void *devid)
{
struct pxamci_host *host = devid;
unsigned int ireg;
@@ -399,13 +399,13 @@
.set_ios = pxamci_set_ios,
};
-static void pxamci_dma_irq(int dma, void *devid, struct pt_regs *regs)
+static void pxamci_dma_irq(int dma, void *devid)
{
printk(KERN_ERR "DMA%d: IRQ???\n", dma);
DCSR(dma) = DCSR_STARTINTR|DCSR_ENDINTR|DCSR_BUSERR;
}
-static irqreturn_t pxamci_detect_irq(int irq, void *devid, struct pt_regs *regs)
+static irqreturn_t pxamci_detect_irq(int irq, void *devid)
{
struct pxamci_host *host = mmc_priv(devid);
diff --git a/drivers/mmc/sdhci.c b/drivers/mmc/sdhci.c
index 20711ac..6d02434 100644
--- a/drivers/mmc/sdhci.c
+++ b/drivers/mmc/sdhci.c
@@ -985,7 +985,7 @@
}
}
-static irqreturn_t sdhci_irq(int irq, void *dev_id, struct pt_regs *regs)
+static irqreturn_t sdhci_irq(int irq, void *dev_id)
{
irqreturn_t result;
struct sdhci_host* host = dev_id;
diff --git a/drivers/mmc/wbsd.c b/drivers/mmc/wbsd.c
index 88c6f0b..ced309b 100644
--- a/drivers/mmc/wbsd.c
+++ b/drivers/mmc/wbsd.c
@@ -1256,7 +1256,7 @@
* Interrupt handling
*/
-static irqreturn_t wbsd_irq(int irq, void *dev_id, struct pt_regs *regs)
+static irqreturn_t wbsd_irq(int irq, void *dev_id)
{
struct wbsd_host *host = dev_id;
int isr;