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Merge branch 'for-next/ptrace' into for-next/core

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* for-next/ptrace:
  arm64: syscall: Pass 'orig_x0' as first argument to native system call
  arm64: ptrace: Keep 'orig_x0' in-sync with x0 on syscall entry
  arm64/fpsimd: ptrace: Fix inactive SVE and SSVE regsets
This commit is contained in:
Will Deacon
2026-08-14 10:16:11 +00:00
parent de5e5f9b99 5a87e8c7f3
commit 8e10aaf503
2 changed files with 61 additions and 6 deletions
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13
arch/arm64/include/asm/syscall_wrapper.h
View File

@@ -10,13 +10,13 @@
#include <asm/ptrace.h>
#define SC_ARM64_REGS_TO_ARGS(x, ...) \
#ifdef CONFIG_COMPAT
#define COMPAT_SC_ARM64_REGS_TO_ARGS(x, ...) \
__MAP(x,__SC_ARGS \
,,regs->regs[0],,regs->regs[1],,regs->regs[2] \
,,regs->regs[3],,regs->regs[4],,regs->regs[5])
#ifdef CONFIG_COMPAT
#define COMPAT_SYSCALL_DEFINEx(x, name, ...) \
asmlinkage long __arm64_compat_sys##name(const struct pt_regs *regs); \
ALLOW_ERROR_INJECTION(__arm64_compat_sys##name, ERRNO); \
@@ -24,7 +24,7 @@
static inline long __do_compat_sys##name(__MAP(x,__SC_DECL,__VA_ARGS__)); \
asmlinkage long __arm64_compat_sys##name(const struct pt_regs *regs) \
{ \
return __se_compat_sys##name(SC_ARM64_REGS_TO_ARGS(x,__VA_ARGS__)); \
return __se_compat_sys##name(COMPAT_SC_ARM64_REGS_TO_ARGS(x,__VA_ARGS__)); \
} \
static long __se_compat_sys##name(__MAP(x,__SC_LONG,__VA_ARGS__)) \
{ \
@@ -46,6 +46,11 @@
#endif /* CONFIG_COMPAT */
#define SC_ARM64_REGS_TO_ARGS(x, ...) \
__MAP(x,__SC_ARGS \
,,regs->orig_x0,,regs->regs[1],,regs->regs[2] \
,,regs->regs[3],,regs->regs[4],,regs->regs[5])
#define __SYSCALL_DEFINEx(x, name, ...) \
asmlinkage long __arm64_sys##name(const struct pt_regs *regs); \
ALLOW_ERROR_INJECTION(__arm64_sys##name, ERRNO); \

54
arch/arm64/kernel/ptrace.c
View File

@@ -560,6 +560,42 @@ static int gpr_get(struct task_struct *target,
return membuf_write(&to, uregs, sizeof(*uregs));
}
static void update_syscall_orig_x0_after_ptrace(struct task_struct *target)
{
struct pt_regs *regs = task_pt_regs(target);
struct kernel_siginfo *info = target->last_siginfo;
/*
* Skip the update for NO_SYSCALL (set either by the user or the
* tracer), as regs[0] holds the return value (see the comment in
* el0_svc_common()) and can be unwound using syscall_rollback().
*/
if (regs->syscallno == NO_SYSCALL)
return;
/* We should only be called when target is in a ptrace stop */
if (WARN_ON_ONCE(!info))
return;
/*
* For compat tasks, orig_r0 is provided directly through GPR index
* 17.
*/
if (is_compat_thread(task_thread_info(target)))
return;
/*
* Don't update orig_x0 for a syscall-exit-stop, as x0 now contains the
* return value of the system call.
*/
if ((info->si_code & ~0x80) == SIGTRAP &&
target->ptrace_message == PTRACE_EVENTMSG_SYSCALL_EXIT) {
return;
}
regs->orig_x0 = regs->regs[0];
}
static int gpr_set(struct task_struct *target, const struct user_regset *regset,
unsigned int pos, unsigned int count,
const void *kbuf, const void __user *ubuf)
@@ -575,6 +611,14 @@ static int gpr_set(struct task_struct *target, const struct user_regset *regset,
return -EINVAL;
task_pt_regs(target)->user_regs = newregs;
/*
* Keep orig_x0 authoritative so that seccomp (via
* syscall_get_arguments()), audit and the restart path all see the same
* first argument the syscall is dispatched with, even if it has been
* updated by a tracer.
*/
update_syscall_orig_x0_after_ptrace(target);
return 0;
}
@@ -753,6 +797,12 @@ static int system_call_set(struct task_struct *target,
return ret;
task_pt_regs(target)->syscallno = syscallno;
/*
* Re-sync orig_x0 in case the syscall number has been changed
* from NO_SYSCALL.
*/
update_syscall_orig_x0_after_ptrace(target);
return ret;
}
@@ -801,7 +851,7 @@ static void sve_init_header_from_task(struct user_sve_header *header,
if (active)
header->size = SVE_PT_SIZE(vq, header->flags);
else
header->size = sizeof(header);
header->size = sizeof(*header);
header->max_size = SVE_PT_SIZE(sve_vq_from_vl(header->max_vl),
SVE_PT_REGS_SVE);
}
@@ -837,7 +887,7 @@ static int sve_get_common(struct task_struct *target,
* from the other mode to userspace.
*/
if (header.size == sizeof(header))
return 0;
return to.left;
switch ((header.flags & SVE_PT_REGS_MASK)) {
case SVE_PT_REGS_FPSIMD: