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[ARM] 3759/2: Remove uses of %?
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Patch from Daniel Jacobowitz

The ARM kernel has several uses of asm("foo%?").  %? is a GCC internal
modifier used to output conditional execution predicates.  However, no
version of GCC supports conditionalizing asm statements.  GCC 4.2 will
correctly expand %? to the empty string in user asms.  Earlier versions may
reuse the condition from the previous instruction.  In 'if (foo) asm
("bar%?");' this is somewhat likely to be right... but not reliable.

So, the only safe thing to do is to remove the uses of %?.  I believe
the tlbflush.h occurances were supposed to be removed before, based
on the comment about %? not working at the top of that file.

Old versions of GCC could omit branches around user asms if the asm didn't
mark the condition codes as clobbered.  This problem hasn't been seen on any
recent (3.x or 4.x) GCC, but it could theoretically happen.  So, where
%? was removed a cc clobber was added.

Signed-off-by: Daniel Jacobowitz <[email protected]>
Signed-off-by: Russell King <[email protected]>
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Daniel Jacobowitz authored and Russell King committed Sep 20, 2006
1 parent 681a499 commit 6a39dd6
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Showing 5 changed files with 62 additions and 59 deletions.
2 changes: 1 addition & 1 deletion arch/arm/kernel/traps.c
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Original file line number Diff line number Diff line change
Expand Up @@ -191,7 +191,7 @@ void show_stack(struct task_struct *tsk, unsigned long *sp)
if (tsk != current)
fp = thread_saved_fp(tsk);
else
asm("mov%? %0, fp" : "=r" (fp));
asm("mov %0, fp" : "=r" (fp) : : "cc");

c_backtrace(fp, 0x10);
barrier();
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27 changes: 15 additions & 12 deletions arch/arm/mach-footbridge/dc21285.c
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Original file line number Diff line number Diff line change
Expand Up @@ -69,16 +69,16 @@ dc21285_read_config(struct pci_bus *bus, unsigned int devfn, int where,
if (addr)
switch (size) {
case 1:
asm("ldr%?b %0, [%1, %2]"
: "=r" (v) : "r" (addr), "r" (where));
asm("ldrb %0, [%1, %2]"
: "=r" (v) : "r" (addr), "r" (where) : "cc");
break;
case 2:
asm("ldr%?h %0, [%1, %2]"
: "=r" (v) : "r" (addr), "r" (where));
asm("ldrh %0, [%1, %2]"
: "=r" (v) : "r" (addr), "r" (where) : "cc");
break;
case 4:
asm("ldr%? %0, [%1, %2]"
: "=r" (v) : "r" (addr), "r" (where));
asm("ldr %0, [%1, %2]"
: "=r" (v) : "r" (addr), "r" (where) : "cc");
break;
}

Expand All @@ -103,16 +103,19 @@ dc21285_write_config(struct pci_bus *bus, unsigned int devfn, int where,
if (addr)
switch (size) {
case 1:
asm("str%?b %0, [%1, %2]"
: : "r" (value), "r" (addr), "r" (where));
asm("strb %0, [%1, %2]"
: : "r" (value), "r" (addr), "r" (where)
: "cc");
break;
case 2:
asm("str%?h %0, [%1, %2]"
: : "r" (value), "r" (addr), "r" (where));
asm("strh %0, [%1, %2]"
: : "r" (value), "r" (addr), "r" (where)
: "cc");
break;
case 4:
asm("str%? %0, [%1, %2]"
: : "r" (value), "r" (addr), "r" (where));
asm("str %0, [%1, %2]"
: : "r" (value), "r" (addr), "r" (where)
: "cc");
break;
}

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8 changes: 4 additions & 4 deletions arch/arm/vfp/vfpinstr.h
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Original file line number Diff line number Diff line change
Expand Up @@ -73,14 +73,14 @@

#define fmrx(_vfp_) ({ \
u32 __v; \
asm("mrc%? p10, 7, %0, " vfpreg(_vfp_) ", cr0, 0 @ fmrx %0, " #_vfp_ \
: "=r" (__v)); \
asm("mrc p10, 7, %0, " vfpreg(_vfp_) ", cr0, 0 @ fmrx %0, " #_vfp_ \
: "=r" (__v) : : "cc"); \
__v; \
})

#define fmxr(_vfp_,_var_) \
asm("mcr%? p10, 7, %0, " vfpreg(_vfp_) ", cr0, 0 @ fmxr " #_vfp_ ", %0" \
: : "r" (_var_))
asm("mcr p10, 7, %0, " vfpreg(_vfp_) ", cr0, 0 @ fmxr " #_vfp_ ", %0" \
: : "r" (_var_) : "cc")

u32 vfp_single_cpdo(u32 inst, u32 fpscr);
u32 vfp_single_cprt(u32 inst, u32 fpscr, struct pt_regs *regs);
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8 changes: 4 additions & 4 deletions include/asm-arm/arch-l7200/io.h
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Original file line number Diff line number Diff line change
Expand Up @@ -31,9 +31,9 @@
static inline unsigned int __arch_getw(unsigned long a)
{
unsigned int value;
__asm__ __volatile__("ldr%?h %0, [%1, #0] @ getw"
__asm__ __volatile__("ldrh %0, [%1, #0] @ getw"
: "=&r" (value)
: "r" (a));
: "r" (a) : "cc");
return value;
}

Expand All @@ -42,8 +42,8 @@ static inline unsigned int __arch_getw(unsigned long a)

static inline void __arch_putw(unsigned int value, unsigned long a)
{
__asm__ __volatile__("str%?h %0, [%1, #0] @ putw"
: : "r" (value), "r" (a));
__asm__ __volatile__("strh %0, [%1, #0] @ putw"
: : "r" (value), "r" (a) : "cc");
}

/*
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76 changes: 38 additions & 38 deletions include/asm-arm/tlbflush.h
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Original file line number Diff line number Diff line change
Expand Up @@ -247,16 +247,16 @@ static inline void local_flush_tlb_all(void)
const unsigned int __tlb_flag = __cpu_tlb_flags;

if (tlb_flag(TLB_WB))
asm("mcr%? p15, 0, %0, c7, c10, 4" : : "r" (zero));
asm("mcr p15, 0, %0, c7, c10, 4" : : "r" (zero) : "cc");

if (tlb_flag(TLB_V3_FULL))
asm("mcr%? p15, 0, %0, c6, c0, 0" : : "r" (zero));
asm("mcr p15, 0, %0, c6, c0, 0" : : "r" (zero) : "cc");
if (tlb_flag(TLB_V4_U_FULL | TLB_V6_U_FULL))
asm("mcr%? p15, 0, %0, c8, c7, 0" : : "r" (zero));
asm("mcr p15, 0, %0, c8, c7, 0" : : "r" (zero) : "cc");
if (tlb_flag(TLB_V4_D_FULL | TLB_V6_D_FULL))
asm("mcr%? p15, 0, %0, c8, c6, 0" : : "r" (zero));
asm("mcr p15, 0, %0, c8, c6, 0" : : "r" (zero) : "cc");
if (tlb_flag(TLB_V4_I_FULL | TLB_V6_I_FULL))
asm("mcr%? p15, 0, %0, c8, c5, 0" : : "r" (zero));
asm("mcr p15, 0, %0, c8, c5, 0" : : "r" (zero) : "cc");
}

static inline void local_flush_tlb_mm(struct mm_struct *mm)
Expand All @@ -266,25 +266,25 @@ static inline void local_flush_tlb_mm(struct mm_struct *mm)
const unsigned int __tlb_flag = __cpu_tlb_flags;

if (tlb_flag(TLB_WB))
asm("mcr%? p15, 0, %0, c7, c10, 4" : : "r" (zero));
asm("mcr p15, 0, %0, c7, c10, 4" : : "r" (zero) : "cc");

if (cpu_isset(smp_processor_id(), mm->cpu_vm_mask)) {
if (tlb_flag(TLB_V3_FULL))
asm("mcr%? p15, 0, %0, c6, c0, 0" : : "r" (zero));
asm("mcr p15, 0, %0, c6, c0, 0" : : "r" (zero) : "cc");
if (tlb_flag(TLB_V4_U_FULL))
asm("mcr%? p15, 0, %0, c8, c7, 0" : : "r" (zero));
asm("mcr p15, 0, %0, c8, c7, 0" : : "r" (zero) : "cc");
if (tlb_flag(TLB_V4_D_FULL))
asm("mcr%? p15, 0, %0, c8, c6, 0" : : "r" (zero));
asm("mcr p15, 0, %0, c8, c6, 0" : : "r" (zero) : "cc");
if (tlb_flag(TLB_V4_I_FULL))
asm("mcr%? p15, 0, %0, c8, c5, 0" : : "r" (zero));
asm("mcr p15, 0, %0, c8, c5, 0" : : "r" (zero) : "cc");
}

if (tlb_flag(TLB_V6_U_ASID))
asm("mcr%? p15, 0, %0, c8, c7, 2" : : "r" (asid));
asm("mcr p15, 0, %0, c8, c7, 2" : : "r" (asid) : "cc");
if (tlb_flag(TLB_V6_D_ASID))
asm("mcr%? p15, 0, %0, c8, c6, 2" : : "r" (asid));
asm("mcr p15, 0, %0, c8, c6, 2" : : "r" (asid) : "cc");
if (tlb_flag(TLB_V6_I_ASID))
asm("mcr%? p15, 0, %0, c8, c5, 2" : : "r" (asid));
asm("mcr p15, 0, %0, c8, c5, 2" : : "r" (asid) : "cc");
}

static inline void
Expand All @@ -296,27 +296,27 @@ local_flush_tlb_page(struct vm_area_struct *vma, unsigned long uaddr)
uaddr = (uaddr & PAGE_MASK) | ASID(vma->vm_mm);

if (tlb_flag(TLB_WB))
asm("mcr%? p15, 0, %0, c7, c10, 4" : : "r" (zero));
asm("mcr p15, 0, %0, c7, c10, 4" : : "r" (zero));

if (cpu_isset(smp_processor_id(), vma->vm_mm->cpu_vm_mask)) {
if (tlb_flag(TLB_V3_PAGE))
asm("mcr%? p15, 0, %0, c6, c0, 0" : : "r" (uaddr));
asm("mcr p15, 0, %0, c6, c0, 0" : : "r" (uaddr) : "cc");
if (tlb_flag(TLB_V4_U_PAGE))
asm("mcr%? p15, 0, %0, c8, c7, 1" : : "r" (uaddr));
asm("mcr p15, 0, %0, c8, c7, 1" : : "r" (uaddr) : "cc");
if (tlb_flag(TLB_V4_D_PAGE))
asm("mcr%? p15, 0, %0, c8, c6, 1" : : "r" (uaddr));
asm("mcr p15, 0, %0, c8, c6, 1" : : "r" (uaddr) : "cc");
if (tlb_flag(TLB_V4_I_PAGE))
asm("mcr%? p15, 0, %0, c8, c5, 1" : : "r" (uaddr));
asm("mcr p15, 0, %0, c8, c5, 1" : : "r" (uaddr) : "cc");
if (!tlb_flag(TLB_V4_I_PAGE) && tlb_flag(TLB_V4_I_FULL))
asm("mcr%? p15, 0, %0, c8, c5, 0" : : "r" (zero));
asm("mcr p15, 0, %0, c8, c5, 0" : : "r" (zero) : "cc");
}

if (tlb_flag(TLB_V6_U_PAGE))
asm("mcr%? p15, 0, %0, c8, c7, 1" : : "r" (uaddr));
asm("mcr p15, 0, %0, c8, c7, 1" : : "r" (uaddr) : "cc");
if (tlb_flag(TLB_V6_D_PAGE))
asm("mcr%? p15, 0, %0, c8, c6, 1" : : "r" (uaddr));
asm("mcr p15, 0, %0, c8, c6, 1" : : "r" (uaddr) : "cc");
if (tlb_flag(TLB_V6_I_PAGE))
asm("mcr%? p15, 0, %0, c8, c5, 1" : : "r" (uaddr));
asm("mcr p15, 0, %0, c8, c5, 1" : : "r" (uaddr) : "cc");
}

static inline void local_flush_tlb_kernel_page(unsigned long kaddr)
Expand All @@ -327,31 +327,31 @@ static inline void local_flush_tlb_kernel_page(unsigned long kaddr)
kaddr &= PAGE_MASK;

if (tlb_flag(TLB_WB))
asm("mcr%? p15, 0, %0, c7, c10, 4" : : "r" (zero));
asm("mcr p15, 0, %0, c7, c10, 4" : : "r" (zero) : "cc");

if (tlb_flag(TLB_V3_PAGE))
asm("mcr%? p15, 0, %0, c6, c0, 0" : : "r" (kaddr));
asm("mcr p15, 0, %0, c6, c0, 0" : : "r" (kaddr) : "cc");
if (tlb_flag(TLB_V4_U_PAGE))
asm("mcr%? p15, 0, %0, c8, c7, 1" : : "r" (kaddr));
asm("mcr p15, 0, %0, c8, c7, 1" : : "r" (kaddr) : "cc");
if (tlb_flag(TLB_V4_D_PAGE))
asm("mcr%? p15, 0, %0, c8, c6, 1" : : "r" (kaddr));
asm("mcr p15, 0, %0, c8, c6, 1" : : "r" (kaddr) : "cc");
if (tlb_flag(TLB_V4_I_PAGE))
asm("mcr%? p15, 0, %0, c8, c5, 1" : : "r" (kaddr));
asm("mcr p15, 0, %0, c8, c5, 1" : : "r" (kaddr) : "cc");
if (!tlb_flag(TLB_V4_I_PAGE) && tlb_flag(TLB_V4_I_FULL))
asm("mcr%? p15, 0, %0, c8, c5, 0" : : "r" (zero));
asm("mcr p15, 0, %0, c8, c5, 0" : : "r" (zero) : "cc");

if (tlb_flag(TLB_V6_U_PAGE))
asm("mcr%? p15, 0, %0, c8, c7, 1" : : "r" (kaddr));
asm("mcr p15, 0, %0, c8, c7, 1" : : "r" (kaddr) : "cc");
if (tlb_flag(TLB_V6_D_PAGE))
asm("mcr%? p15, 0, %0, c8, c6, 1" : : "r" (kaddr));
asm("mcr p15, 0, %0, c8, c6, 1" : : "r" (kaddr) : "cc");
if (tlb_flag(TLB_V6_I_PAGE))
asm("mcr%? p15, 0, %0, c8, c5, 1" : : "r" (kaddr));
asm("mcr p15, 0, %0, c8, c5, 1" : : "r" (kaddr) : "cc");

/* The ARM ARM states that the completion of a TLB maintenance
* operation is only guaranteed by a DSB instruction
*/
if (tlb_flag(TLB_V6_U_PAGE | TLB_V6_D_PAGE | TLB_V6_I_PAGE))
asm("mcr%? p15, 0, %0, c7, c10, 4" : : "r" (zero));
asm("mcr p15, 0, %0, c7, c10, 4" : : "r" (zero) : "cc");
}

/*
Expand All @@ -373,20 +373,20 @@ static inline void flush_pmd_entry(pmd_t *pmd)
const unsigned int __tlb_flag = __cpu_tlb_flags;

if (tlb_flag(TLB_DCLEAN))
asm("mcr%? p15, 0, %0, c7, c10, 1 @ flush_pmd"
: : "r" (pmd));
asm("mcr p15, 0, %0, c7, c10, 1 @ flush_pmd"
: : "r" (pmd) : "cc");
if (tlb_flag(TLB_WB))
asm("mcr%? p15, 0, %0, c7, c10, 4 @ flush_pmd"
: : "r" (zero));
asm("mcr p15, 0, %0, c7, c10, 4 @ flush_pmd"
: : "r" (zero) : "cc");
}

static inline void clean_pmd_entry(pmd_t *pmd)
{
const unsigned int __tlb_flag = __cpu_tlb_flags;

if (tlb_flag(TLB_DCLEAN))
asm("mcr%? p15, 0, %0, c7, c10, 1 @ flush_pmd"
: : "r" (pmd));
asm("mcr p15, 0, %0, c7, c10, 1 @ flush_pmd"
: : "r" (pmd) : "cc");
}

#undef tlb_flag
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