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RISC-V Fixes for 6.5-rc8

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* The vector ucontext extension has been extended with vlenb.
 * The vector registers ELF core dump note type has been changed to avoid
   aliasing with the CSR type used in embedded systems.
 * Support for accessing vector registers via ptrace() has been reverted.
 * Another build fix for the ISA spec changes around Zifencei/Zicsr that
   manifests on some systems built with binutils-2.37 and gcc-11.2.
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Merge tag 'riscv-for-linus-6.5-rc8' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux

Pull RISC-V fixes from Palmer Dabbelt:
 "This is obviously not ideal, particularly for something this late in
  the cycle.

  Unfortunately we found some uABI issues in the vector support while
  reviewing the GDB port, which has triggered a revert -- probably a
  good sign we should have reviewed GDB before merging this, I guess I
  just dropped the ball because I was so worried about the context
  extension and libc suff I forgot. Hence the late revert.

  There's some risk here as we're still exposing the vector context for
  signal handlers, but changing that would have meant reverting all of
  the vector support. The issues we've found so far have been fixed
  already and they weren't absolute showstoppers, so we're essentially
  just playing it safe by holding ptrace support for another release (or
  until we get through a proper userspace code review).

  Summary:

   - The vector ucontext extension has been extended with vlenb

   - The vector registers ELF core dump note type has been changed to
     avoid aliasing with the CSR type used in embedded systems

   - Support for accessing vector registers via ptrace() has been
     reverted

   - Another build fix for the ISA spec changes around Zifencei/Zicsr
     that manifests on some systems built with binutils-2.37 and
     gcc-11.2"

* tag 'riscv-for-linus-6.5-rc8' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux:
  riscv: Fix build errors using binutils2.37 toolchains
  RISC-V: vector: export VLENB csr in __sc_riscv_v_state
  RISC-V: Remove ptrace support for vectors
This commit is contained in:
Linus Torvalds 2023-08-25 09:29:47 -07:00
commit 4942fed84b
5 changed files with 7 additions and 75 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

8
arch/riscv/Kconfig
View File

@ -580,15 +580,15 @@ config TOOLCHAIN_NEEDS_EXPLICIT_ZICSR_ZIFENCEI
and Zifencei are supported in binutils from version 2.36 onwards.
To make life easier, and avoid forcing toolchains that default to a
newer ISA spec to version 2.2, relax the check to binutils >= 2.36.
For clang < 17 or GCC < 11.1.0, for which this is not possible, this is
dealt with in CONFIG_TOOLCHAIN_NEEDS_OLD_ISA_SPEC.
For clang < 17 or GCC < 11.3.0, for which this is not possible or need
special treatment, this is dealt with in TOOLCHAIN_NEEDS_OLD_ISA_SPEC.
config TOOLCHAIN_NEEDS_OLD_ISA_SPEC
def_bool y
depends on TOOLCHAIN_NEEDS_EXPLICIT_ZICSR_ZIFENCEI
# https://github.com/llvm/llvm-project/commit/22e199e6afb1263c943c0c0d4498694e15bf8a16
# https://gcc.gnu.org/git/?p=gcc.git;a=commit;h=b03be74bad08c382da47e048007a78fa3fb4ef49
depends on (CC_IS_CLANG && CLANG_VERSION < 170000) || (CC_IS_GCC && GCC_VERSION < 110100)
# https://gcc.gnu.org/git/?p=gcc.git;a=commit;h=d29f5d6ab513c52fd872f532c492e35ae9fd6671
depends on (CC_IS_CLANG && CLANG_VERSION < 170000) || (CC_IS_GCC && GCC_VERSION < 110300)
help
Certain versions of clang and GCC do not support zicsr and zifencei via
-march. This option causes an older ISA spec compatible with these older

3
arch/riscv/include/asm/vector.h
View File

@ -70,8 +70,9 @@ static __always_inline void __vstate_csr_save(struct __riscv_v_ext_state *dest)
"csrr %1, " __stringify(CSR_VTYPE) "\n\t"
"csrr %2, " __stringify(CSR_VL) "\n\t"
"csrr %3, " __stringify(CSR_VCSR) "\n\t"
"csrr %4, " __stringify(CSR_VLENB) "\n\t"
: "=r" (dest->vstart), "=r" (dest->vtype), "=r" (dest->vl),
"=r" (dest->vcsr) : :);
"=r" (dest->vcsr), "=r" (dest->vlenb) : :);
}
static __always_inline void __vstate_csr_restore(struct __riscv_v_ext_state *src)

1
arch/riscv/include/uapi/asm/ptrace.h
View File

@ -97,6 +97,7 @@ struct __riscv_v_ext_state {
unsigned long vl;
unsigned long vtype;
unsigned long vcsr;
unsigned long vlenb;
void *datap;
/*
* In signal handler, datap will be set a correct user stack offset

69
arch/riscv/kernel/ptrace.c
View File

@ -25,9 +25,6 @@ enum riscv_regset {
#ifdef CONFIG_FPU
REGSET_F,
#endif
#ifdef CONFIG_RISCV_ISA_V
REGSET_V,
#endif
};
static int riscv_gpr_get(struct task_struct *target,
@ -84,61 +81,6 @@ static int riscv_fpr_set(struct task_struct *target,
}
#endif
#ifdef CONFIG_RISCV_ISA_V
static int riscv_vr_get(struct task_struct *target,
const struct user_regset *regset,
struct membuf to)
{
struct __riscv_v_ext_state *vstate = &target->thread.vstate;
if (!riscv_v_vstate_query(task_pt_regs(target)))
return -EINVAL;
/*
* Ensure the vector registers have been saved to the memory before
* copying them to membuf.
*/
if (target == current)
riscv_v_vstate_save(current, task_pt_regs(current));
/* Copy vector header from vstate. */
membuf_write(&to, vstate, offsetof(struct __riscv_v_ext_state, datap));
membuf_zero(&to, sizeof(vstate->datap));
/* Copy all the vector registers from vstate. */
return membuf_write(&to, vstate->datap, riscv_v_vsize);
}
static int riscv_vr_set(struct task_struct *target,
const struct user_regset *regset,
unsigned int pos, unsigned int count,
const void *kbuf, const void __user *ubuf)
{
int ret, size;
struct __riscv_v_ext_state *vstate = &target->thread.vstate;
if (!riscv_v_vstate_query(task_pt_regs(target)))
return -EINVAL;
/* Copy rest of the vstate except datap */
ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf, vstate, 0,
offsetof(struct __riscv_v_ext_state, datap));
if (unlikely(ret))
return ret;
/* Skip copy datap. */
size = sizeof(vstate->datap);
count -= size;
ubuf += size;
/* Copy all the vector registers. */
pos = 0;
ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf, vstate->datap,
0, riscv_v_vsize);
return ret;
}
#endif
static const struct user_regset riscv_user_regset[] = {
[REGSET_X] = {
.core_note_type = NT_PRSTATUS,
@ -158,17 +100,6 @@ static const struct user_regset riscv_user_regset[] = {
.set = riscv_fpr_set,
},
#endif
#ifdef CONFIG_RISCV_ISA_V
[REGSET_V] = {
.core_note_type = NT_RISCV_VECTOR,
.align = 16,
.n = ((32 * RISCV_MAX_VLENB) +
sizeof(struct __riscv_v_ext_state)) / sizeof(__u32),
.size = sizeof(__u32),
.regset_get = riscv_vr_get,
.set = riscv_vr_set,
},
#endif
};
static const struct user_regset_view riscv_user_native_view = {

1
include/uapi/linux/elf.h
View File

@ -443,7 +443,6 @@ typedef struct elf64_shdr {
#define NT_MIPS_DSP 0x800 /* MIPS DSP ASE registers */
#define NT_MIPS_FP_MODE 0x801 /* MIPS floating-point mode */
#define NT_MIPS_MSA 0x802 /* MIPS SIMD registers */
#define NT_RISCV_VECTOR 0x900 /* RISC-V vector registers */
#define NT_LOONGARCH_CPUCFG 0xa00 /* LoongArch CPU config registers */
#define NT_LOONGARCH_CSR 0xa01 /* LoongArch control and status registers */
#define NT_LOONGARCH_LSX 0xa02 /* LoongArch Loongson SIMD Extension registers */