iv/linux
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

RISC-V: add non-alternative fallback for riscv_has_extension_[un]likely()

Browse Source 
The has_fpu() check, which in turn calls riscv_has_extension_likely(),
relies on alternatives to figure out whether the system has an FPU.
As a result, it will malfunction on XIP kernels, as they do not support
the alternatives mechanism.

When alternatives support is not present, fall back to using
__riscv_isa_extension_available() in riscv_has_extension_[un]likely()
instead stead, which handily takes the same argument, so that kernels
that do not support alternatives can accurately report the presence of
FPU support.

Fixes: 702e64550b12 ("riscv: fpu: switch has_fpu() to riscv_has_extension_likely()")
Link: https://lore.kernel.org/all/ad445951-3d13-4644-94d9-e0989cda39c3@spud/
Signed-off-by: Conor Dooley <conor.dooley@microchip.com>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Reviewed-by: Jason A. Donenfeld <Jason@zx2c4.com>
Link: https://lore.kernel.org/r/20230324100538.3514663-2-conor.dooley@microchip.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
This commit is contained in:
Conor Dooley 2023-03-24 10:05:38 +00:00 committed by Palmer Dabbelt
parent fe15c26ee2
commit 1aa866931b
No known key found for this signature in database
GPG Key ID: 2E1319F35FBB1889
1 changed files with 30 additions and 20 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

50
arch/riscv/include/asm/hwcap.h
View File

@ -57,18 +57,31 @@ struct riscv_isa_ext_data {
unsigned int isa_ext_id;
};
unsigned long riscv_isa_extension_base(const unsigned long *isa_bitmap);
#define riscv_isa_extension_mask(ext) BIT_MASK(RISCV_ISA_EXT_##ext)
bool __riscv_isa_extension_available(const unsigned long *isa_bitmap, int bit);
#define riscv_isa_extension_available(isa_bitmap, ext) \
__riscv_isa_extension_available(isa_bitmap, RISCV_ISA_EXT_##ext)
static __always_inline bool
riscv_has_extension_likely(const unsigned long ext)
{
compiletime_assert(ext < RISCV_ISA_EXT_MAX,
"ext must be < RISCV_ISA_EXT_MAX");
asm_volatile_goto(
ALTERNATIVE("j %l[l_no]", "nop", 0, %[ext], 1)
:
: [ext] "i" (ext)
:
: l_no);
if (IS_ENABLED(CONFIG_RISCV_ALTERNATIVE)) {
asm_volatile_goto(
ALTERNATIVE("j %l[l_no]", "nop", 0, %[ext], 1)
:
: [ext] "i" (ext)
:
: l_no);
} else {
if (!__riscv_isa_extension_available(NULL, ext))
goto l_no;
}
return true;
l_no:
@ -81,26 +94,23 @@ riscv_has_extension_unlikely(const unsigned long ext)
compiletime_assert(ext < RISCV_ISA_EXT_MAX,
"ext must be < RISCV_ISA_EXT_MAX");
asm_volatile_goto(
ALTERNATIVE("nop", "j %l[l_yes]", 0, %[ext], 1)
:
: [ext] "i" (ext)
:
: l_yes);
if (IS_ENABLED(CONFIG_RISCV_ALTERNATIVE)) {
asm_volatile_goto(
ALTERNATIVE("nop", "j %l[l_yes]", 0, %[ext], 1)
:
: [ext] "i" (ext)
:
: l_yes);
} else {
if (__riscv_isa_extension_available(NULL, ext))
goto l_yes;
}
return false;
l_yes:
return true;
}
unsigned long riscv_isa_extension_base(const unsigned long *isa_bitmap);
#define riscv_isa_extension_mask(ext) BIT_MASK(RISCV_ISA_EXT_##ext)
bool __riscv_isa_extension_available(const unsigned long *isa_bitmap, int bit);
#define riscv_isa_extension_available(isa_bitmap, ext) \
__riscv_isa_extension_available(isa_bitmap, RISCV_ISA_EXT_##ext)
#endif
#endif /* _ASM_RISCV_HWCAP_H */