| Message ID | 1353631803-4853-10-git-send-email-anton.vorontsov@linaro.org |
|---|---|
| State | New |
| Headers | show |
> The function only saves initial arch-specific "no FIQ" instruction, by > placing the code into set_fiq_handler() we can: > > - Have less code and logic in the platform-specific files; > - Have the code that manages FIQ vector overwriting in one place, i.e. > don't spread the logic around. > > p.s. Also, I noticed that we saved no_fiq_insn w/o bothering about > !CONFIG_CPU_USE_DOMAINS case, but set_fiq_handler() handles this case > specifically. I wonder, was that on purpose, e.g. it does not matter for > init_FIQ(), or it was just overlooked? In the latter case, the patch fixes > the issue. ... > diff --git a/arch/arm/kernel/fiq.c b/arch/arm/kernel/fiq.c > index 9bf3a60..3602df6 100644 > --- a/arch/arm/kernel/fiq.c > +++ b/arch/arm/kernel/fiq.c > @@ -49,6 +49,7 @@ > #include <asm/mach/irq.h> > > static unsigned long no_fiq_insn; > +static int got_no_fiq_insn; > > /* Default reacquire function > * - we always relinquish FIQ control > @@ -78,11 +79,14 @@ void show_fiq_list(struct seq_file *p, int prec) > > void set_fiq_handler(void *start, unsigned int length) > { > -#if defined(CONFIG_CPU_USE_DOMAINS) > - memcpy((void *)0xffff001c, start, length); > -#else > - memcpy(vectors_page + 0x1c, start, length); > + unsigned long *addr = (void *)0xffff001c; > + > +#ifndef CONFIG_CPU_USE_DOMAINS > + addr = vectors_page + 0x1c; > #endif > + if (!cmpxchg(&got_no_fiq_insn, 0, 1)) > + no_fiq_insn = *addr; > + memcpy(addr, start, length); > flush_icache_range(0xffff001c, 0xffff001c + length); > if (!vectors_high()) > flush_icache_range(0x1c, 0x1c + length); > @@ -126,8 +130,3 @@ EXPORT_SYMBOL(__set_fiq_regs); /* defined in fiqasm.S */ > EXPORT_SYMBOL(__get_fiq_regs); /* defined in fiqasm.S */ > EXPORT_SYMBOL(claim_fiq); > EXPORT_SYMBOL(release_fiq); > - > -void __init init_FIQ(void) > -{ > - no_fiq_insn = *(unsigned long *)0xffff001c; it seems that this is wrong. In this case we have an uninitialized variable and sequential call claim_fiq and release_fiq could be fatal. FIXME please. ---
On Fri, Nov 23, 2012 at 07:40:30AM +0400, Alexander Shiyan wrote: [...] > > static unsigned long no_fiq_insn; > > +static int got_no_fiq_insn; > > @@ -78,11 +79,14 @@ void show_fiq_list(struct seq_file *p, int prec) > > > > void set_fiq_handler(void *start, unsigned int length) > > { > > -#if defined(CONFIG_CPU_USE_DOMAINS) > > - memcpy((void *)0xffff001c, start, length); > > -#else > > - memcpy(vectors_page + 0x1c, start, length); > > + unsigned long *addr = (void *)0xffff001c; > > + > > +#ifndef CONFIG_CPU_USE_DOMAINS > > + addr = vectors_page + 0x1c; > > #endif > > + if (!cmpxchg(&got_no_fiq_insn, 0, 1)) > > + no_fiq_insn = *addr; > > + memcpy(addr, start, length); > > flush_icache_range(0xffff001c, 0xffff001c + length); > > if (!vectors_high()) > > flush_icache_range(0x1c, 0x1c + length); > > @@ -126,8 +130,3 @@ EXPORT_SYMBOL(__set_fiq_regs); /* defined in fiqasm.S */ > > - > > -void __init init_FIQ(void) > > -{ > > - no_fiq_insn = *(unsigned long *)0xffff001c; > > it seems that this is wrong. In this case we have an uninitialized variable and > sequential call claim_fiq and release_fiq could be fatal. FIXME please. Um... I don't think I understand, can you please elaborate? Thanks, Anton.
> On Fri, Nov 23, 2012 at 07:40:30AM +0400, Alexander Shiyan wrote: > [...] > > > static unsigned long no_fiq_insn; > > > +static int got_no_fiq_insn; > > > @@ -78,11 +79,14 @@ void show_fiq_list(struct seq_file *p, int prec) > > > > > > void set_fiq_handler(void *start, unsigned int length) > > > { > > > -#if defined(CONFIG_CPU_USE_DOMAINS) > > > - memcpy((void *)0xffff001c, start, length); > > > -#else > > > - memcpy(vectors_page + 0x1c, start, length); > > > + unsigned long *addr = (void *)0xffff001c; > > > + > > > +#ifndef CONFIG_CPU_USE_DOMAINS > > > + addr = vectors_page + 0x1c; > > > #endif > > > + if (!cmpxchg(&got_no_fiq_insn, 0, 1)) > > > + no_fiq_insn = *addr; > > > + memcpy(addr, start, length); > > > flush_icache_range(0xffff001c, 0xffff001c + length); > > > if (!vectors_high()) > > > flush_icache_range(0x1c, 0x1c + length); > > > @@ -126,8 +130,3 @@ EXPORT_SYMBOL(__set_fiq_regs); /* defined in fiqasm.S */ > > > - > > > -void __init init_FIQ(void) > > > -{ > > > - no_fiq_insn = *(unsigned long *)0xffff001c; > > > > it seems that this is wrong. In this case we have an uninitialized variable and > > sequential call claim_fiq and release_fiq could be fatal. FIXME please. > > Um... I don't think I understand, can you please elaborate? OK, I'll try to explain it. At the end of the release_fiq function we have a call fiq_op. For the default handler - is a fiq_def_op function, and we call this function with the option "relinquish = 0", i.e. we want to restore old fiq_handler. But if we do not call set_fiq_handler never before, we will have an uninitialized no_fiq_insn variable. ---
On Fri, Nov 23, 2012 at 10:27:51AM +0400, Alexander Shiyan wrote: > > On Fri, Nov 23, 2012 at 07:40:30AM +0400, Alexander Shiyan wrote: > > [...] > > > > static unsigned long no_fiq_insn; > > > > +static int got_no_fiq_insn; > > > > @@ -78,11 +79,14 @@ void show_fiq_list(struct seq_file *p, int prec) > > > > > > > > void set_fiq_handler(void *start, unsigned int length) > > > > { > > > > -#if defined(CONFIG_CPU_USE_DOMAINS) > > > > - memcpy((void *)0xffff001c, start, length); > > > > -#else > > > > - memcpy(vectors_page + 0x1c, start, length); > > > > + unsigned long *addr = (void *)0xffff001c; > > > > + > > > > +#ifndef CONFIG_CPU_USE_DOMAINS > > > > + addr = vectors_page + 0x1c; > > > > #endif > > > > + if (!cmpxchg(&got_no_fiq_insn, 0, 1)) > > > > + no_fiq_insn = *addr; > > > > + memcpy(addr, start, length); > > > > flush_icache_range(0xffff001c, 0xffff001c + length); > > > > if (!vectors_high()) > > > > flush_icache_range(0x1c, 0x1c + length); > > > > @@ -126,8 +130,3 @@ EXPORT_SYMBOL(__set_fiq_regs); /* defined in fiqasm.S */ > > > > - > > > > -void __init init_FIQ(void) > > > > -{ > > > > - no_fiq_insn = *(unsigned long *)0xffff001c; > > > > > > it seems that this is wrong. In this case we have an uninitialized variable and > > > sequential call claim_fiq and release_fiq could be fatal. FIXME please. > > > > Um... I don't think I understand, can you please elaborate? > > OK, I'll try to explain it. > At the end of the release_fiq function we have a call fiq_op. For the default > handler - is a fiq_def_op function, and we call this function with the option > "relinquish = 0", i.e. we want to restore old fiq_handler. But if we do not call > set_fiq_handler never before, we will have an uninitialized no_fiq_insn variable. It should not matter when or in what order anyone calls the set_fiq_handler(), since it stores "no FIQ instruction" into no_fiq_insn at its first invocation: if (!cmpxchg(&got_no_fiq_insn, 0, 1)) no_fiq_insn = *addr; If we never called set_fiq_handler() before, during release_fiq() we'll: 1. Copy the initial instruction from the vector page to 'no_fiq_insn'; 2. Copy the initial instruction from 'no_fiq_insn' to the vector page; So no_fiq_insn gets initialized, then we just instantly write the same value back. Thanks, Anton.
> On Fri, Nov 23, 2012 at 10:27:51AM +0400, Alexander Shiyan wrote: > > > On Fri, Nov 23, 2012 at 07:40:30AM +0400, Alexander Shiyan wrote: > > > [...] > > > > > static unsigned long no_fiq_insn; > > > > > +static int got_no_fiq_insn; > > > > > @@ -78,11 +79,14 @@ void show_fiq_list(struct seq_file *p, int prec) > > > > > > > > > > void set_fiq_handler(void *start, unsigned int length) > > > > > { > > > > > -#if defined(CONFIG_CPU_USE_DOMAINS) > > > > > - memcpy((void *)0xffff001c, start, length); > > > > > -#else > > > > > - memcpy(vectors_page + 0x1c, start, length); > > > > > + unsigned long *addr = (void *)0xffff001c; > > > > > + > > > > > +#ifndef CONFIG_CPU_USE_DOMAINS > > > > > + addr = vectors_page + 0x1c; > > > > > #endif > > > > > + if (!cmpxchg(&got_no_fiq_insn, 0, 1)) > > > > > + no_fiq_insn = *addr; > > > > > + memcpy(addr, start, length); > > > > > flush_icache_range(0xffff001c, 0xffff001c + length); > > > > > if (!vectors_high()) > > > > > flush_icache_range(0x1c, 0x1c + length); > > > > > @@ -126,8 +130,3 @@ EXPORT_SYMBOL(__set_fiq_regs); /* defined in fiqasm.S */ > > > > > - > > > > > -void __init init_FIQ(void) > > > > > -{ > > > > > - no_fiq_insn = *(unsigned long *)0xffff001c; > > > > > > > > it seems that this is wrong. In this case we have an uninitialized variable and > > > > sequential call claim_fiq and release_fiq could be fatal. FIXME please. > > > > > > Um... I don't think I understand, can you please elaborate? > > > > OK, I'll try to explain it. > > At the end of the release_fiq function we have a call fiq_op. For the default > > handler - is a fiq_def_op function, and we call this function with the option > > "relinquish = 0", i.e. we want to restore old fiq_handler. But if we do not call > > set_fiq_handler never before, we will have an uninitialized no_fiq_insn variable. > > It should not matter when or in what order anyone calls the > set_fiq_handler(), since it stores "no FIQ instruction" into no_fiq_insn > at its first invocation: > > if (!cmpxchg(&got_no_fiq_insn, 0, 1)) > no_fiq_insn = *addr; > > If we never called set_fiq_handler() before, during release_fiq() we'll: > > 1. Copy the initial instruction from the vector page to 'no_fiq_insn'; > 2. Copy the initial instruction from 'no_fiq_insn' to the vector page; > > So no_fiq_insn gets initialized, then we just instantly write the same > value back. got_no_fiq_insn also not initialized. I think as a whole on this issue requires additional comments from Russell as the author of implementation. PS: In any case, I can reproduce it and check it out if you send me a patchset to my email as an attachment. ---
On Fri, Nov 23, 2012 at 11:36:01AM +0400, Alexander Shiyan wrote: [...] > got_no_fiq_insn also not initialized. It is static, so by definition it is initialized to 0. > I think as a whole on this issue requires additional comments from Russell > as the author of implementation. > > PS: In any case, I can reproduce it and check it out if you send me a patchset > to my email as an attachment. Sent privately. Thanks, Anton.
On Thu, Nov 22, 2012 at 11:51:38PM -0800, Anton Vorontsov wrote: > On Fri, Nov 23, 2012 at 11:36:01AM +0400, Alexander Shiyan wrote: > [...] > > got_no_fiq_insn also not initialized. > > It is static, so by definition it is initialized to 0. > > > I think as a whole on this issue requires additional comments from Russell > > as the author of implementation. > > > > PS: In any case, I can reproduce it and check it out if you send me a patchset > > to my email as an attachment. > > Sent privately. Andrew, Arnd, just FYI, it works for Alexander. ----- Forwarded message from Alexander Shiyan <shc_work@mail.ru> ----- Date: Tue, 27 Nov 2012 12:42:50 +0400 From: Alexander Shiyan <shc_work@mail.ru> To: Anton Vorontsov <anton.vorontsov@linaro.org> Subject: Re[2]: FIQ > Hello Alexander, > > On Tue, Nov 27, 2012 at 12:14:28PM +0400, Alexander Shiyan wrote: > > Sorry, I lost the original message to the correct answer. > > Today I had a test of removal init_FIQ. > > The test took place on a custom board with a custom ARM CLPS711X OSS audio > > driver, which uses the FIQ interrupts. Everything works fine. > > Nice! Thanks a lot for testing! > > Can you please reply to the original thread, with the > > Tested-by: Alexander Shiyan <shc_work@mail.ru> > ? > > This will help pushing the series forward, plus will give you a credit for > your efforts. I am lost thread in my mailbox, you can just copy/paste my reply and ping for Arnd.
diff --git a/arch/arm/include/asm/mach/irq.h b/arch/arm/include/asm/mach/irq.h index 8be5ba9..6e70ae3 100644 --- a/arch/arm/include/asm/mach/irq.h +++ b/arch/arm/include/asm/mach/irq.h @@ -18,10 +18,8 @@ struct seq_file; * This is internal. Do not use it. */ #ifdef CONFIG_FIQ -extern void init_FIQ(void); extern void show_fiq_list(struct seq_file *, int); #else -static inline void init_FIQ(void) {} static inline void show_fiq_list(struct seq_file *p, int prec) {} #endif diff --git a/arch/arm/kernel/fiq.c b/arch/arm/kernel/fiq.c index 9bf3a60..3602df6 100644 --- a/arch/arm/kernel/fiq.c +++ b/arch/arm/kernel/fiq.c @@ -49,6 +49,7 @@ #include <asm/mach/irq.h> static unsigned long no_fiq_insn; +static int got_no_fiq_insn; /* Default reacquire function * - we always relinquish FIQ control @@ -78,11 +79,14 @@ void show_fiq_list(struct seq_file *p, int prec) void set_fiq_handler(void *start, unsigned int length) { -#if defined(CONFIG_CPU_USE_DOMAINS) - memcpy((void *)0xffff001c, start, length); -#else - memcpy(vectors_page + 0x1c, start, length); + unsigned long *addr = (void *)0xffff001c; + +#ifndef CONFIG_CPU_USE_DOMAINS + addr = vectors_page + 0x1c; #endif + if (!cmpxchg(&got_no_fiq_insn, 0, 1)) + no_fiq_insn = *addr; + memcpy(addr, start, length); flush_icache_range(0xffff001c, 0xffff001c + length); if (!vectors_high()) flush_icache_range(0x1c, 0x1c + length); @@ -126,8 +130,3 @@ EXPORT_SYMBOL(__set_fiq_regs); /* defined in fiqasm.S */ EXPORT_SYMBOL(__get_fiq_regs); /* defined in fiqasm.S */ EXPORT_SYMBOL(claim_fiq); EXPORT_SYMBOL(release_fiq); - -void __init init_FIQ(void) -{ - no_fiq_insn = *(unsigned long *)0xffff001c; -} diff --git a/arch/arm/mach-rpc/irq.c b/arch/arm/mach-rpc/irq.c index 07770c8..2d915ba 100644 --- a/arch/arm/mach-rpc/irq.c +++ b/arch/arm/mach-rpc/irq.c @@ -151,7 +151,5 @@ void __init rpc_init_irq(void) break; } } - - init_FIQ(); } diff --git a/arch/arm/plat-mxc/avic.c b/arch/arm/plat-mxc/avic.c index 426980c..b173dc6 100644 --- a/arch/arm/plat-mxc/avic.c +++ b/arch/arm/plat-mxc/avic.c @@ -216,8 +216,5 @@ void __init mxc_init_irq(void __iomem *irqbase) for (i = 0; i < 8; i++) __raw_writel(0, avic_base + AVIC_NIPRIORITY(i)); - /* Initialize FIQ */ - init_FIQ(); - printk(KERN_INFO "MXC IRQ initialized\n"); } diff --git a/arch/arm/plat-mxc/tzic.c b/arch/arm/plat-mxc/tzic.c index 8a5a633..889267c 100644 --- a/arch/arm/plat-mxc/tzic.c +++ b/arch/arm/plat-mxc/tzic.c @@ -191,9 +191,6 @@ void __init tzic_init_irq(void __iomem *irqbase) for (i = 0; i < 4; i++, irq_base += 32) tzic_init_gc(i, irq_base); - /* Initialize FIQ */ - init_FIQ(); - pr_info("TrustZone Interrupt Controller (TZIC) initialized\n"); } diff --git a/arch/arm/plat-s3c24xx/irq.c b/arch/arm/plat-s3c24xx/irq.c index 531d6a4..66b8856 100644 --- a/arch/arm/plat-s3c24xx/irq.c +++ b/arch/arm/plat-s3c24xx/irq.c @@ -532,8 +532,6 @@ void __init s3c24xx_init_irq(void) int irqno; int i; - init_FIQ(); - irqdbf("s3c2410_init_irq: clearing interrupt status flags\n"); /* first, clear all interrupts pending... */
The function only saves initial arch-specific "no FIQ" instruction, by placing the code into set_fiq_handler() we can: - Have less code and logic in the platform-specific files; - Have the code that manages FIQ vector overwriting in one place, i.e. don't spread the logic around. p.s. Also, I noticed that we saved no_fiq_insn w/o bothering about !CONFIG_CPU_USE_DOMAINS case, but set_fiq_handler() handles this case specifically. I wonder, was that on purpose, e.g. it does not matter for init_FIQ(), or it was just overlooked? In the latter case, the patch fixes the issue. Signed-off-by: Anton Vorontsov <anton.vorontsov@linaro.org> --- arch/arm/include/asm/mach/irq.h | 2 -- arch/arm/kernel/fiq.c | 17 ++++++++--------- arch/arm/mach-rpc/irq.c | 2 -- arch/arm/plat-mxc/avic.c | 3 --- arch/arm/plat-mxc/tzic.c | 3 --- arch/arm/plat-s3c24xx/irq.c | 2 -- 6 files changed, 8 insertions(+), 21 deletions(-)