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Diffstat (limited to 'arch/x86/um/os-Linux/mcontext.c')
-rw-r--r--arch/x86/um/os-Linux/mcontext.c218
1 files changed, 217 insertions, 1 deletions
diff --git a/arch/x86/um/os-Linux/mcontext.c b/arch/x86/um/os-Linux/mcontext.c
index 37decaa74761..a21403df6663 100644
--- a/arch/x86/um/os-Linux/mcontext.c
+++ b/arch/x86/um/os-Linux/mcontext.c
@@ -1,7 +1,10 @@
// SPDX-License-Identifier: GPL-2.0
-#include <sys/ucontext.h>
#define __FRAME_OFFSETS
+#include <linux/errno.h>
+#include <linux/string.h>
+#include <sys/ucontext.h>
#include <asm/ptrace.h>
+#include <asm/sigcontext.h>
#include <sysdep/ptrace.h>
#include <sysdep/mcontext.h>
#include <arch.h>
@@ -18,6 +21,10 @@ void get_regs_from_mc(struct uml_pt_regs *regs, mcontext_t *mc)
COPY2(UESP, ESP); /* sic */
COPY(EBX); COPY(EDX); COPY(ECX); COPY(EAX);
COPY(EIP); COPY_SEG_CPL3(CS); COPY(EFL); COPY_SEG_CPL3(SS);
+#undef COPY2
+#undef COPY
+#undef COPY_SEG
+#undef COPY_SEG_CPL3
#else
#define COPY2(X,Y) regs->gp[X/sizeof(unsigned long)] = mc->gregs[REG_##Y]
#define COPY(X) regs->gp[X/sizeof(unsigned long)] = mc->gregs[REG_##X]
@@ -29,6 +36,8 @@ void get_regs_from_mc(struct uml_pt_regs *regs, mcontext_t *mc)
COPY2(EFLAGS, EFL);
COPY2(CS, CSGSFS);
regs->gp[SS / sizeof(unsigned long)] = mc->gregs[REG_CSGSFS] >> 48;
+#undef COPY2
+#undef COPY
#endif
}
@@ -42,3 +51,210 @@ void mc_set_rip(void *_mc, void *target)
mc->gregs[REG_RIP] = (unsigned long)target;
#endif
}
+
+/* Same thing, but the copy macros are turned around. */
+void get_mc_from_regs(struct uml_pt_regs *regs, mcontext_t *mc, int single_stepping)
+{
+#ifdef __i386__
+#define COPY2(X,Y) mc->gregs[REG_##Y] = regs->gp[X]
+#define COPY(X) mc->gregs[REG_##X] = regs->gp[X]
+#define COPY_SEG(X) mc->gregs[REG_##X] = regs->gp[X] & 0xffff;
+#define COPY_SEG_CPL3(X) mc->gregs[REG_##X] = (regs->gp[X] & 0xffff) | 3;
+ COPY_SEG(GS); COPY_SEG(FS); COPY_SEG(ES); COPY_SEG(DS);
+ COPY(EDI); COPY(ESI); COPY(EBP);
+ COPY2(UESP, ESP); /* sic */
+ COPY(EBX); COPY(EDX); COPY(ECX); COPY(EAX);
+ COPY(EIP); COPY_SEG_CPL3(CS); COPY(EFL); COPY_SEG_CPL3(SS);
+#else
+#define COPY2(X,Y) mc->gregs[REG_##Y] = regs->gp[X/sizeof(unsigned long)]
+#define COPY(X) mc->gregs[REG_##X] = regs->gp[X/sizeof(unsigned long)]
+ COPY(R8); COPY(R9); COPY(R10); COPY(R11);
+ COPY(R12); COPY(R13); COPY(R14); COPY(R15);
+ COPY(RDI); COPY(RSI); COPY(RBP); COPY(RBX);
+ COPY(RDX); COPY(RAX); COPY(RCX); COPY(RSP);
+ COPY(RIP);
+ COPY2(EFLAGS, EFL);
+ mc->gregs[REG_CSGSFS] = mc->gregs[REG_CSGSFS] & 0xffffffffffffl;
+ mc->gregs[REG_CSGSFS] |= (regs->gp[SS / sizeof(unsigned long)] & 0xffff) << 48;
+#endif
+
+ if (single_stepping)
+ mc->gregs[REG_EFL] |= X86_EFLAGS_TF;
+ else
+ mc->gregs[REG_EFL] &= ~X86_EFLAGS_TF;
+}
+
+#ifdef CONFIG_X86_32
+struct _xstate_64 {
+ struct _fpstate_64 fpstate;
+ struct _header xstate_hdr;
+ struct _ymmh_state ymmh;
+ /* New processor state extensions go here: */
+};
+
+/* Not quite the right structures as these contain more information */
+int um_i387_from_fxsr(struct _fpstate_32 *i387,
+ const struct _fpstate_64 *fxsave);
+int um_fxsr_from_i387(struct _fpstate_64 *fxsave,
+ const struct _fpstate_32 *from);
+#else
+#define _xstate_64 _xstate
+#endif
+
+static struct _fpstate *get_fpstate(struct stub_data *data,
+ mcontext_t *mcontext,
+ int *fp_size)
+{
+ struct _fpstate *res;
+
+ /* Assume floating point registers are on the same page */
+ res = (void *)(((unsigned long)mcontext->fpregs &
+ (UM_KERN_PAGE_SIZE - 1)) +
+ (unsigned long)&data->sigstack[0]);
+
+ if ((void *)res + sizeof(struct _fpstate) >
+ (void *)data->sigstack + sizeof(data->sigstack))
+ return NULL;
+
+ if (res->sw_reserved.magic1 != FP_XSTATE_MAGIC1) {
+ *fp_size = sizeof(struct _fpstate);
+ } else {
+ char *magic2_addr;
+
+ magic2_addr = (void *)res;
+ magic2_addr += res->sw_reserved.extended_size;
+ magic2_addr -= FP_XSTATE_MAGIC2_SIZE;
+
+ /* We still need to be within our stack */
+ if ((void *)magic2_addr >
+ (void *)data->sigstack + sizeof(data->sigstack))
+ return NULL;
+
+ /* If we do not read MAGIC2, then we did something wrong */
+ if (*(__u32 *)magic2_addr != FP_XSTATE_MAGIC2)
+ return NULL;
+
+ /* Remove MAGIC2 from the size, we do not save/restore it */
+ *fp_size = res->sw_reserved.extended_size -
+ FP_XSTATE_MAGIC2_SIZE;
+ }
+
+ return res;
+}
+
+int get_stub_state(struct uml_pt_regs *regs, struct stub_data *data,
+ unsigned long *fp_size_out)
+{
+ mcontext_t *mcontext;
+ struct _fpstate *fpstate_stub;
+ struct _xstate_64 *xstate_stub;
+ int fp_size, xstate_size;
+
+ /* mctx_offset is verified by wait_stub_done_seccomp */
+ mcontext = (void *)&data->sigstack[data->mctx_offset];
+
+ get_regs_from_mc(regs, mcontext);
+
+ fpstate_stub = get_fpstate(data, mcontext, &fp_size);
+ if (!fpstate_stub)
+ return -EINVAL;
+
+#ifdef CONFIG_X86_32
+ xstate_stub = (void *)&fpstate_stub->_fxsr_env;
+ xstate_size = fp_size - offsetof(struct _fpstate_32, _fxsr_env);
+#else
+ xstate_stub = (void *)fpstate_stub;
+ xstate_size = fp_size;
+#endif
+
+ if (fp_size_out)
+ *fp_size_out = xstate_size;
+
+ if (xstate_size > host_fp_size)
+ return -ENOSPC;
+
+ memcpy(&regs->fp, xstate_stub, xstate_size);
+
+ /* We do not need to read the x86_64 FS_BASE/GS_BASE registers as
+ * we do not permit userspace to set them directly.
+ */
+
+#ifdef CONFIG_X86_32
+ /* Read the i387 legacy FP registers */
+ if (um_fxsr_from_i387((void *)&regs->fp, fpstate_stub))
+ return -EINVAL;
+#endif
+
+ return 0;
+}
+
+/* Copied because we cannot include regset.h here. */
+struct task_struct;
+struct user_regset;
+struct membuf {
+ void *p;
+ size_t left;
+};
+
+int fpregs_legacy_get(struct task_struct *target,
+ const struct user_regset *regset,
+ struct membuf to);
+
+int set_stub_state(struct uml_pt_regs *regs, struct stub_data *data,
+ int single_stepping)
+{
+ mcontext_t *mcontext;
+ struct _fpstate *fpstate_stub;
+ struct _xstate_64 *xstate_stub;
+ int fp_size, xstate_size;
+
+ /* mctx_offset is verified by wait_stub_done_seccomp */
+ mcontext = (void *)&data->sigstack[data->mctx_offset];
+
+ if ((unsigned long)mcontext < (unsigned long)data->sigstack ||
+ (unsigned long)mcontext >
+ (unsigned long) data->sigstack +
+ sizeof(data->sigstack) - sizeof(*mcontext))
+ return -EINVAL;
+
+ get_mc_from_regs(regs, mcontext, single_stepping);
+
+ fpstate_stub = get_fpstate(data, mcontext, &fp_size);
+ if (!fpstate_stub)
+ return -EINVAL;
+
+#ifdef CONFIG_X86_32
+ xstate_stub = (void *)&fpstate_stub->_fxsr_env;
+ xstate_size = fp_size - offsetof(struct _fpstate_32, _fxsr_env);
+#else
+ xstate_stub = (void *)fpstate_stub;
+ xstate_size = fp_size;
+#endif
+
+ memcpy(xstate_stub, &regs->fp, xstate_size);
+
+#ifdef __i386__
+ /*
+ * On x86, the GDT entries are updated by arch_set_tls.
+ */
+
+ /* Store the i387 legacy FP registers which the host will use */
+ if (um_i387_from_fxsr(fpstate_stub, (void *)&regs->fp))
+ return -EINVAL;
+#else
+ /*
+ * On x86_64, we need to sync the FS_BASE/GS_BASE registers using the
+ * arch specific data.
+ */
+ if (data->arch_data.fs_base != regs->gp[FS_BASE / sizeof(unsigned long)]) {
+ data->arch_data.fs_base = regs->gp[FS_BASE / sizeof(unsigned long)];
+ data->arch_data.sync |= STUB_SYNC_FS_BASE;
+ }
+ if (data->arch_data.gs_base != regs->gp[GS_BASE / sizeof(unsigned long)]) {
+ data->arch_data.gs_base = regs->gp[GS_BASE / sizeof(unsigned long)];
+ data->arch_data.sync |= STUB_SYNC_GS_BASE;
+ }
+#endif
+
+ return 0;
+}
generated by cgit (git 2.34.1) at 2025-06-08 21:17:43 +0000