[U-Boot] [PATCH] nios2: fix out of reach case for do_reset
The "Nios II Processor Reference Handbook" said, "call can transfer execution anywhere within the 256 MByte range determined by PC31..28. The Nios II GNU linker does not automatically handle cases in which the address is out of this range."
So we have to use registered "callr" instruction to do the job.
Signed-off-by: Thomas Chou thomas@wytron.com.tw --- arch/nios2/cpu/cpu.c | 14 ++++++++------ 1 files changed, 8 insertions(+), 6 deletions(-)
diff --git a/arch/nios2/cpu/cpu.c b/arch/nios2/cpu/cpu.c index 6379534..d9c3003 100644 --- a/arch/nios2/cpu/cpu.c +++ b/arch/nios2/cpu/cpu.c @@ -40,11 +40,13 @@ int checkcpu (void) return (0); }
- -int do_reset (void) +int do_reset(void) { - void (*rst)(void) = (void(*)(void))CONFIG_SYS_RESET_ADDR; - disable_interrupts (); - rst(); - return(0); + disable_interrupts(); + __asm__ __volatile__ ( + "callr %0" + : + : "r" (CONFIG_SYS_RESET_ADDR) + ); + return 0; }
On Thu, Aug 12, 2010 at 10:40 PM, Thomas Chou wrote:
The "Nios II Processor Reference Handbook" said, "call can transfer execution anywhere within the 256 MByte range determined by PC31..28. The Nios II GNU linker does not automatically handle cases in which the address is out of this range."
So we have to use registered "callr" instruction to do the job.
doesnt NIOS have an insn to call indirectly via a register ? typically that's how function pointers should be handled when gcc generates code. -mike
On 08/13/2010 10:52 AM, Mike Frysinger wrote:
On Thu, Aug 12, 2010 at 10:40 PM, Thomas Chou wrote:
The "Nios II Processor Reference Handbook" said, "call can transfer execution anywhere within the 256 MByte range determined by PC31..28. The Nios II GNU linker does not automatically handle cases in which the address is out of this range."
So we have to use registered "callr" instruction to do the job.
doesnt NIOS have an insn to call indirectly via a register ? typically that's how function pointers should be handled when gcc generates code. -mike
Hi Mike,
The nios2 does have "callr" instruction to do registered call. But the nios2 gcc didn't generate correct code when the reset vector is passed as a constant. It just generated a direct "call", which was wrong when the reset vector was not located in the same 256MB span as u-boot. The gcc does generate correct "callr" if the reset vector is passed as an argument. As Altera said, this is a limitation (or bug?) of nios2 toolchain.
So I'd take a similar inline asm approach as we do in linux kernel.
Best regards, Thomas
As a comment, that patch looks pretty ugly. I might suggest an inline function (called "callr" or "nios2_callr") which encapsulates the __asm__. That would make the code much easier to read.
You could put the inline function in one of the asm headers.
-brad
Thomas Chou wrote:
The "Nios II Processor Reference Handbook" said, "call can transfer execution anywhere within the 256 MByte range determined by PC31..28. The Nios II GNU linker does not automatically handle cases in which the address is out of this range."
So we have to use registered "callr" instruction to do the job.
Signed-off-by: Thomas Chou thomas@wytron.com.tw
arch/nios2/cpu/cpu.c | 14 ++++++++------ 1 files changed, 8 insertions(+), 6 deletions(-)
diff --git a/arch/nios2/cpu/cpu.c b/arch/nios2/cpu/cpu.c index 6379534..d9c3003 100644 --- a/arch/nios2/cpu/cpu.c +++ b/arch/nios2/cpu/cpu.c @@ -40,11 +40,13 @@ int checkcpu (void) return (0); }
-int do_reset (void) +int do_reset(void) {
- void (*rst)(void) = (void(*)(void))CONFIG_SYS_RESET_ADDR;
- disable_interrupts ();
- rst();
- return(0);
- disable_interrupts();
- __asm__ __volatile__ (
- "callr %0"
- :
- : "r" (CONFIG_SYS_RESET_ADDR)
- );
- return 0;
}
On 08/14/2010 07:51 AM, Brad Parker wrote:
As a comment, that patch looks pretty ugly. I might suggest an inline function (called "callr" or "nios2_callr") which encapsulates the __asm__. That would make the code much easier to read.
You could put the inline function in one of the asm headers.
-brad
Hi Brad,
Thanks. I will add a macro for the inline asm.
- Thomas
There is a limitation (or bug?) of nios2 toolchain. The nios2 gcc didn't generate correct code when the reset vector is passed as a constant. It just generated a direct "call", which was wrong when the reset vector was not located in the same 256MB span as u-boot.
The "Nios II Processor Reference Handbook" said, "call can transfer execution anywhere within the 256 MByte range determined by PC31..28. The Nios II GNU linker does not automatically handle cases in which the address is out of this range."
So we have to use registered "callr" instruction to do the job.
Signed-off-by: Thomas Chou thomas@wytron.com.tw --- v2, add a macro for the inlince asm nios2_callr.
arch/nios2/cpu/cpu.c | 11 +++++------ arch/nios2/include/asm/system.h | 5 +++++ 2 files changed, 10 insertions(+), 6 deletions(-)
diff --git a/arch/nios2/cpu/cpu.c b/arch/nios2/cpu/cpu.c index 6379534..d9c6544 100644 --- a/arch/nios2/cpu/cpu.c +++ b/arch/nios2/cpu/cpu.c @@ -40,11 +40,10 @@ int checkcpu (void) return (0); }
- -int do_reset (void) +int do_reset(void) { - void (*rst)(void) = (void(*)(void))CONFIG_SYS_RESET_ADDR; - disable_interrupts (); - rst(); - return(0); + disable_interrupts(); + /* indirect call to go beyond 256MB limitation of toolchain */ + nios2_callr(CONFIG_SYS_RESET_ADDR); + return 0; } diff --git a/arch/nios2/include/asm/system.h b/arch/nios2/include/asm/system.h index bb03ca5..086d92b 100644 --- a/arch/nios2/include/asm/system.h +++ b/arch/nios2/include/asm/system.h @@ -56,4 +56,9 @@ ((flags & NIOS2_STATUS_PIE_MSK) == 0x0); \ })
+/* indirect call to go beyond 256MB limitation of toolchain */ +#define nios2_callr(addr) __asm__ __volatile__ ( \ + "callr %0" \ + : : "r" (addr)) + #endif /* __ASM_NIOS2_SYSTEM_H */
Thomas,
Applied to: git://git.denx.de/u-boot-nios.git next
Thanks, --Scott
Thomas Chou wrote:
There is a limitation (or bug?) of nios2 toolchain. The nios2 gcc didn't generate correct code when the reset vector is passed as a constant. It just generated a direct "call", which was wrong when the reset vector was not located in the same 256MB span as u-boot.
The "Nios II Processor Reference Handbook" said, "call can transfer execution anywhere within the 256 MByte range determined by PC31..28. The Nios II GNU linker does not automatically handle cases in which the address is out of this range."
So we have to use registered "callr" instruction to do the job.
Signed-off-by: Thomas Chou thomas@wytron.com.tw
v2, add a macro for the inlince asm nios2_callr.
arch/nios2/cpu/cpu.c | 11 +++++------ arch/nios2/include/asm/system.h | 5 +++++ 2 files changed, 10 insertions(+), 6 deletions(-)
diff --git a/arch/nios2/cpu/cpu.c b/arch/nios2/cpu/cpu.c index 6379534..d9c6544 100644 --- a/arch/nios2/cpu/cpu.c +++ b/arch/nios2/cpu/cpu.c @@ -40,11 +40,10 @@ int checkcpu (void) return (0); }
-int do_reset (void) +int do_reset(void) {
- void (*rst)(void) = (void(*)(void))CONFIG_SYS_RESET_ADDR;
- disable_interrupts ();
- rst();
- return(0);
- disable_interrupts();
- /* indirect call to go beyond 256MB limitation of toolchain */
- nios2_callr(CONFIG_SYS_RESET_ADDR);
- return 0;
} diff --git a/arch/nios2/include/asm/system.h b/arch/nios2/include/asm/system.h index bb03ca5..086d92b 100644 --- a/arch/nios2/include/asm/system.h +++ b/arch/nios2/include/asm/system.h @@ -56,4 +56,9 @@ ((flags & NIOS2_STATUS_PIE_MSK) == 0x0); \ })
+/* indirect call to go beyond 256MB limitation of toolchain */ +#define nios2_callr(addr) __asm__ __volatile__ ( \
- "callr %0" \
- : : "r" (addr))
#endif /* __ASM_NIOS2_SYSTEM_H */
participants (4)
-
Brad Parker -
Mike Frysinger -
Scott McNutt -
Thomas Chou