path: root/Documentation
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authorLinus Torvalds <torvalds@linux-foundation.org>2021-05-23 06:07:33 -1000
committerLinus Torvalds <torvalds@linux-foundation.org>2021-05-23 06:07:33 -1000
commit28ceac6959e1db015729c52ec74e0a4ff496c2b8 (patch)
tree1fda20fa530a3bd3f2c96113d644d68921145738 /Documentation
parent4d7620341eda38573a73ab63c33423534fa38eb9 (diff)
parentd72500f992849d31ebae8f821a023660ddd0dcc2 (diff)
Merge tag 'powerpc-5.13-4' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux
Pull powerpc fixes from Michael Ellerman: - Fix breakage of strace (and other ptracers etc.) when using the new scv ABI (Power9 or later with glibc >= 2.33). - Fix early_ioremap() on 64-bit, which broke booting on some machines. Thanks to Dmitry V. Levin, Nicholas Piggin, Alexey Kardashevskiy, and Christophe Leroy. * tag 'powerpc-5.13-4' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux: powerpc/64s/syscall: Fix ptrace syscall info with scv syscalls powerpc/64s/syscall: Use pt_regs.trap to distinguish syscall ABI difference between sc and scv syscalls powerpc: Fix early setup to make early_ioremap() work
Diffstat (limited to 'Documentation')
1 files changed, 10 insertions, 0 deletions
diff --git a/Documentation/powerpc/syscall64-abi.rst b/Documentation/powerpc/syscall64-abi.rst
index dabee3729e5a..56490c4c0c07 100644
--- a/Documentation/powerpc/syscall64-abi.rst
+++ b/Documentation/powerpc/syscall64-abi.rst
@@ -109,6 +109,16 @@ auxiliary vector.
scv 0 syscalls will always behave as PPC_FEATURE2_HTM_NOSC.
+When ptracing system calls (PTRACE_SYSCALL), the pt_regs.trap value contains
+the system call type that can be used to distinguish between sc and scv 0
+system calls, and the different register conventions can be accounted for.
+If the value of (pt_regs.trap & 0xfff0) is 0xc00 then the system call was
+performed with the sc instruction, if it is 0x3000 then the system call was
+performed with the scv 0 instruction.

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