arm64/ptrace: Expose FPMR via ptrace

Add a new regset to expose FPMR via ptrace. It is not added to the FPSIMD
registers since that structure is exposed elsewhere without any allowance
for extension we don't add there.

Signed-off-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20240306-arm64-2023-dpisa-v5-5-c568edc8ed7f@kernel.org
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

diff --git a/arch/arm64/kernel/ptrace.c b/arch/arm64/kernel/ptrace.c
index dc6cf0e37194e428519d7d58524ad0f624f4bebb..aacb45bd36e6b49c5a39e2433193cb5eb55c5148 100644 (file)
--- a/arch/arm64/kernel/ptrace.c
+++ b/arch/arm64/kernel/ptrace.c
@@ -698,6 +698,39 @@ static int tls_set(struct task_struct *target, const struct user_regset *regset,
        return ret;
 }
 
+static int fpmr_get(struct task_struct *target, const struct user_regset *regset,
+                  struct membuf to)
+{
+       if (!system_supports_fpmr())
+               return -EINVAL;
+
+       if (target == current)
+               fpsimd_preserve_current_state();
+
+       return membuf_store(&to, target->thread.uw.fpmr);
+}
+
+static int fpmr_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;
+       unsigned long fpmr;
+
+       if (!system_supports_fpmr())
+               return -EINVAL;
+
+       ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf, &fpmr, 0, count);
+       if (ret)
+               return ret;
+
+       target->thread.uw.fpmr = fpmr;
+
+       fpsimd_flush_task_state(target);
+
+       return 0;
+}
+
 static int system_call_get(struct task_struct *target,
                           const struct user_regset *regset,
                           struct membuf to)
@@ -1419,6 +1452,7 @@ enum aarch64_regset {
        REGSET_HW_BREAK,
        REGSET_HW_WATCH,
 #endif
+       REGSET_FPMR,
        REGSET_SYSTEM_CALL,
 #ifdef CONFIG_ARM64_SVE
        REGSET_SVE,
@@ -1497,6 +1531,14 @@ static const struct user_regset aarch64_regsets[] = {
                .regset_get = system_call_get,
                .set = system_call_set,
        },
+       [REGSET_FPMR] = {
+               .core_note_type = NT_ARM_FPMR,
+               .n = 1,
+               .size = sizeof(u64),
+               .align = sizeof(u64),
+               .regset_get = fpmr_get,
+               .set = fpmr_set,
+       },
 #ifdef CONFIG_ARM64_SVE
        [REGSET_SVE] = { /* Scalable Vector Extension */
                .core_note_type = NT_ARM_SVE,

diff --git a/include/uapi/linux/elf.h b/include/uapi/linux/elf.h
index 9417309b7230e3e3d6bad378cbcb3c54f7c33e1f..b54b313bcf0730a0d48a7aa006ec9e775269b7da 100644 (file)
--- a/include/uapi/linux/elf.h
+++ b/include/uapi/linux/elf.h
@@ -440,6 +440,7 @@ typedef struct elf64_shdr {
 #define NT_ARM_SSVE    0x40b           /* ARM Streaming SVE registers */
 #define NT_ARM_ZA      0x40c           /* ARM SME ZA registers */
 #define NT_ARM_ZT      0x40d           /* ARM SME ZT registers */
+#define NT_ARM_FPMR    0x40e           /* ARM floating point mode register */
 #define NT_ARC_V2      0x600           /* ARCv2 accumulator/extra registers */
 #define NT_VMCOREDD    0x700           /* Vmcore Device Dump Note */
 #define NT_MIPS_DSP    0x800           /* MIPS DSP ASE registers */